Qal
Alluvium
Quaternary
Silt, sand, and gravel of stream beds, flood plains, and terraces
RB002
Ruby
Unconsol
Qs
TKi
Intrusive rocks
Late Cretaceous(?) or Early Tertiary(?)
Granite, diorite, quartz monzonite, and  may include dikes of varying composition and texture, older intrusives of the greenstone complex (mi), and  hornfelds zones surrounding intrusive rocks.
Ign
TKe
Extrusive rocks
Cretaceous or Tertiary
Basaltic, andesitic, and rhyolitic flows, tuffs, and breccias, and a few dacite flows; interbedded  sandstone and shale.  Flows commonly porphyritic and gently dipping. Probably greater than 500 feet thick.
TKvr
Ks
Shaktolik group
late Early Cretaceous to Late Cretaceous
Graywacke, shale, grit, and conglomerate.   Type section on the Shaktolik River approximately 120 miles west of the Ruby quad.  Thickness estimated to be more that 4800 feet along the lower Yukon River.  Unit is obsolete and no longer used.  On map, this
plant fossils, marine mollusks
Sed
Km
Ku
Ungalik conglomerate
Cretaceous
Conglomerate, grit, some graywacke.  Boulders as much as 2 ft in diameter: Sorting and bedding poor.   Believed  to be several hundred ft thick on the Melozitna River north of the Ruby quad.   Patton and Bickel estimate minimum thickness of 1200 feet.  S
Kuc
Kc
Chert and argillite
Chert and argillite with interbedded rhyolitic tuff, sandstone, and grit.
Fragmentary fossil imprint identified as small immature ammonite of Cretaceous or Jurassic type.
Pig
ira
Pre-Cretaceous
Granite, monzonite and diorite altered to augen gniess and mica schist.  Locally contains younger granitic dikes.
Meta
PzZrqs
mi
Metamorphic igneous rock
Carboniferous (?) Late Paleozoic
Greenstone, locally some gray to red chert, greenstone tuff, and graywacke. Greenstone altered from  basalt, diabase, and andesite extrusives and diorite, diabase, gabbro, and pyroxenite intrusives.  In Nulato quad assigned a Carboniferous(?)  age.  May
JMtu
Dl
Limestone
Devonian
Dark-gray, partly recrystallized limestone carrying light-colored, crushed crinoid columns, and  associated slate, shale, and fine-grained arkose.  No longer on map, lumped in unit JMtu
light-colored, crushed crinoid columns
Ds
Ol
Limestone and dolomite
Ordovician
Dark-gray limestone and brownish-yellow dolomite. Dolomite is common near base of section.   Lies unconformably on older metamorphic rocks.  Massive unit overlain by thinner bedded limestone and dolomite, succeeded by the thickest beds of the series.  To
Ont
mc
Metamorphic complex
Precambrian or Paleozoic
Schist, crystalline limestone, quartzite, greenstone, slate, and phyllite.  Areas of crystalline limestone mapped separately when possible as mcl.
PzZm
mcl
Precambrian or Paleozoic ( may contain Ordovician and Devonian)
Crystalline limestone, may  include rocks of Ordovican or Devonian but generally is more recystallized than Ordovican or Devonian rocks and is associated with schists.
Pzrm
mca
In eastern part of quad, metamorphic complex mapped as two units, mca and mcb.   The older unit, mca is composed of  crystalline limestone and greenstone with some schist and phyllite.
mcb
The younger unit, mcb, contains schist and quatzite with some crystalline limestone, slate, and greenstone.
YZnm
Qac
Undifferentiated alluvial, colluvial, and eolian terrace and slope deposits.  Chiefly silt and very fine sand.  Terrace deposits largely fluival but in part lacustrine; slope deposits primarily eolian and colluvial.
The "Palisades" along the Yukon have yielded Pleistocene vertebrate fauna including mammoth and bison remains.
MZ002
Melozitna
Qfy
Younger flood-plain deposits
Light-gray micaceous silt.  Sand and gravel along streams that drain bendrock uplands.  Characterized physiographically by badrs, oxbows, meander scars, abandoned channels, and other evidence of recent flood-plain building.
Qms
Modified eolian sand deposits
Dark-yellowish-orange and light-gray, fine- to medium-grained eolian sand.  Forms briad sheetlike dune field mantling older floodplain (Qfo) and alluvial terrace (Qac) deposits of the Dulbi Flats.  Deposits have a strong northeast-southwest trend.
Qfo
Older flood-plain deposits
Chiefly light-gray and grayish-orange micaeous silt.  Locally include peat, reworked eolian sand and gravel.  Deposits at or near river level but youthful flood-plain features are much modified or absent.  Contact with Qfy locally gradational and poorly
Qg
Glacial drift
Unsorted bouldery till and isolated moraines; may include some younger solifluction deposits near valley sides.
Ts
Sandstone, Claystone, Conglomerate, and Lignite
Tertiary
Grayish-white granule conglomerate and sandstone, reddish-brown claystone, and lignite coal.  Exposed at river level at the "Palisades" along the Yukon River.
Pollen of probable Miocene age.
Tcb
TKv
Volcanic rock
Tertiary to Late Cretaceous
Indian River, Takhakhdona Hills, and Dulbi River areas- light-gray to pink rhyolite tuff, welded (?) tuff, flows, and breccia.  Subordinate pumice, dark vitrophyre, and obsidian.  In Takhakhdona Hills also includesdark-green to black vesicular basalt flo
Obsidian chippings and artifacts found in archeological site in NW AK may have source in obsidian occurrence north of Little Indian River.
Flows in Tanana and Bettles quads have K-Ar date of 58 m.y.
Tvr
Kg
Granodiorite
Late Cretaceous
Fine- to medium-grained  hornblende-biotite granodiorite with subordinate quartz monzonite and quartz diorite.  (Recoded NSA 2420 March, 1999, per Bill Patton.)
K-Ar date of 82.3 and 89.0 m.y. from the Dulbatna Mountain pluton and 81.5 m.y. from the Indian Mountain pluton in adjoining Hughes quad
Kgd
Kh
Hypabyssal rocks
Small bodies of primarily dacite and rhyolite porphyry.  These intrusives are widespread in volcanic graywacke and mudstone unit (Kgm) and in andesitic rocks (Kv).
Kve
Kqc
Quartz-pebble conglomerate
early Late Cretaceous
Small isolated patches of light-gray quartz-pebble conglomerate and quartzose sandstone.  Minor intercalated with light-colored ashy tuff.  Conglomerate almost wholly of quartz and quartzite clasts.  Intruded and thermally altered by granodiorite (Kg)
Sandstone, Quartz Conglomerate, shale, and siltstone
Probably Late Cretaceous
Non-marine deposits of olive-green, fine- to coarse-grained, crossbedded, quartzose sandstone and grit; quartz-pebble conglomerate, and dark micaeous shale and siltstone.  Ironstone lenses and concretions.  Better sorted and higher % quartz than Kgm.  Pr
Abundant carbonized plant debris
Kss
Igneous pebble-cobble conglomerate
late Early Cretaceous (Albian) may be as young as Late Cretaceous
Massive poorly sorted conglomerate with pebble to cobble sized clasts primarily of mafic intrusive and extrusive rocks and varied colored chert.  Interbedded with fine-grained to gritty (?) , dark-green to green graywacke and mudstone.  grades upward int
Indeterminate pelecypods
Kcg
Kgm
Volcanic graywacke and mudstone
late Early Cretaceous (Albian)
Dark-greenish-gray, fine-grained to gritty(?), poorly sorted graywacke composed largely of first- and second-cycle volcanic debris but locally containing abundant granitic and metamorphic rock debris. Graded bedding common,  Dark gray mudstone interbeds.
Kvgm
Ktg
Tuff, volcanic graywacke, and mudstone
Early Cretaceous
Volcaniclastic rocks of andesitic and dacitic composition.  Crystal-lithic tuff, lithic tuff, volcanic graywacke and mudstone.  Rare andesite flows.  Mapped only along northern edge of this quad and in adjoining HU quad.  Overlies Kv and may grad lateral
Quartz Monzonite
Pinkish coarse-grained porphyritic biotite quartz monzonite.  Becomes gnessic in southern part of the Melozitna pluton.  Altered and slightly cataclastic in small pluton east of Gold Mountain.
K-Ar date 111 m.y. from Melozitna pluton
Kv
Andesitic volcanic rocks
Earliest Cretaceous (Neocomian) but may include Albian age strata
Koyukuk River- Pillow basalt and andesitic flows; andesitic tuffs, volcanic conglomerate, and breccia; chert and fine-grained cherty tuff; coquinoidal limestone composed largely of Buchia sp. Widely altered to a hard dark green hornfels.  Dulbi-Melozitna
Buchia sublaevis, belemnite; Buchia cf.B. crassicollis; Buchia keyserlingi
JPb
Basalt and diabase
Permian to Jurassic.
Spilitic basalt and diabase largely altered to greenstone.  Along contact with Km, altered to mafic hornfels.   Probabaly correlative with similar rocks on strike to the NE in the Tanana and Bettles quads
JMab
JPu
Ultramafics
Permian to Jurassic
Small bodies of serpentinized peridotite and dunite with closely associated gabbro and anorthosite.
Jaum
Pzm
Marble
Paleozoic
Small masses of white to light-gray coarsely crystalline dolomitic and calcareous marble.  Locally altered to calc-silicate hornfels
Dm
PzpCs
Pelitic schist
Paleozoic or Precambrian
Quartz-chlorite-muscovite schist and micaceous quartzite.  Greenschist facies metamorphism.  Subordinate micaceous quartzite and glaucophane-chlorite-muscovite schist.  Unit includes many small bodies of marble, greenstone and greenschist (believed to be
PzpCq
Quartzite
Fine-grained, light-gray quartzite and micaceous quartzite with subordinate quartz-mica schist, marble, and calc-silicate rock.  Stratigraphic relationship to PzpCs uncertain.
PzZrpg
PzpCn
Gneiss and quartzite
Quartz-feldspar-biotite gneiss commonly garnetiferous and locally contains sillimanite.  Almandine-amphibolite facies metamorphism.  Some augen gneiss.  Gray coarse-grained quartzite with thin layers of biotite.  Subordinate quartz-mica schist, marble, a
Silt, sand and gravel of streambeds, flood plains and terraces
NL002
Nulato
Tki
Intrusive Rocks
early Tertiary or Late Cretaceous
Granite and some diorite. Includes numerous dikes and sills and may include hornfels zones
TKg
Graywacke, shale, grit, and conglomerate.   Thickness estimated at 4800 feet.  Unit obsolete, no longer shown on map.
Marine mollusks (late Early K) and plant remains (Late K)
Conglomerate, grit, some graywacke.  Clasts are angular to rounded.  Sorting and bedding are poor.  Boulders as much as 2 feet in diameter.  Type section is near the Ungalik River west of Nulato quad.  Thickness believed to be at least several hundred fe
Metamorphosed igneous rocks
post - Carboniferous
Greenstone, and locally some gray to red chert, dark-gray crystalline limestone, greenstone, tuff, and graywacke.  Greenstone is altered basalt and diabase of probable extrusive origin and diorite, diabase, gabbro, and pyroxenite of probable intrusive or
MzPmi
Late Precambrian or  Early Paleozoic
Quartz-mica schist, quatzite-schist, mica schist, albite-chlorite schist, albite-mica schist, ottrelite-mica schist, glaucophane-mica schist, some phyllite, slate, sheared chert, and quartzite.  Unit superceded.
Recystallized limestone - superceded, see source NL003
vr
Volcanic rocks
unknown
Chiefly basalt and andesite.  Rarely rhyolite, tuff, chert, agglomerate, and breccia.  Probably of several different ages.  Not shown on map as this unit, rather is NSACLASS 1000 and 2330
MzPzi
Qa
None
OP002
Ophir
Qu
Undifferientiated lowland silt, sand, muck, and gravel
Qt
Terrace alluvium
Qc
Colluvium
Volcanics
Early Tertiary  and Late Cretaceous
TKc
Mafic to intermediate volcano-plutonic complexes
TKiv
TKm
Monzonite
TKd
Dikes and subvolcanic rocks
TMg
Tertiary or Late Cretaceous (Not designated on map)
Gabbro
TDg
Ju
Ultramafic rocks
Late Jurassic
Jtu
ph
Harzburgite tectonite of Mount Hurst
Unknown
Harzburgite tectonite of Mount Hurst; relations uncertain
Jium
pc
Cumulate ultramafic rocks of Mount Hurst
Cumulate ultramafic rocks of Mount Hurst: relations uncertain
Sandstone, shale, and conglomerate
Kme
Undifferentiated clastic rocks
Kk
Ksc
Sandstone and conglomerate
Kkn
Fine sandstone, siltstone, and shale
Kls
Limy volcaniclastic sandstone
Kac
Agglomerate, chert, tuff, and sandstone
Kvl
Kvs
Volcaniclastic sandstone
Kvss
Ksa
Sandstone
Ksh
Shale and siltstone
Kvg
Volcanic graywacke and conglomerate
Kvm
TrMs
Triassic, Permian, Pennsylvanian, and Mississippian
Sandstone, grit, and argillite
TrMis
TrMc
Chert, argillite, and volcaniclastic rocks
TrMica
TrMb
Basalt, gabbro, and chert
MDl
Mississippian to Devonian
Pzc
Early Paleozoic
Carbonates
Schistose metamorphic rocks
Early Paleozoic or Late Precambrian
btu
Bedrock unknown
Unknown but likely Precambrian or older
type unknown; relations uncertain
pCu
PzpCs/TrMc
Uncertain
Map shows questionable identification of unit.
pc /TrMc
bu
Qf
Floodplain deposits
?
Kateel River
Terrace deposits
KT?
Light-gray micaceous silt.  Sand and gravel along streams that drain bedrock uplands
KT002
Qna
Nogahabara sand dunes -- active dunes
Active dunes.  Circular body, nearly 5 mi in diameter.  Entriely sand, free of vegetation cover.
Qns
Nogahabara sand dunes -- stabilized dunes
Scattered circular and elliptical bodies of eolian sand.
Older floodplain deposits
Chiefly light-gray and grayish-orange micaceous silt.  Locally includes peat, reworked eolian sand, and gravel
Dark-yellowish-orange and light-gray, fine- to medium-grained eolian sand.  Forms broad sheet-like dune field mantling alluvial silt deposits of the Koyukuk flats and all but tops of bedrock hills in vicinity of Roundabout Mountain.
Qhs
High terrace and slope deposits
Light-gray and grayish-orange micaceous silt.  Subordinate lenses of sand and peat.
QTb
Basalt
early Quaternary or late Tertiary
Nearly horizontal flows of vesicular olivine basalt.  Flows extruded over terrain of moderate relief, ranging in elevation from 175 to over 1,600 feet.
Kgs
Graywacke sandstone and mudstone
Poorly sorted, muddy sandstone (graywacke) interbedded with mudstone.  Chiefly dark-greenish-gray to pale-olive tuffaceous and feldspathic, fine- to very coarse-grained sandstone and subordinate dark-gray mudstone.  Abundant lenses of feldspar and chert
Kgw
Chiefly medium- to dark-gray mudstone and medium-gray to dark-greenish-gray moderately to highly calcareous fine-grained sandstone..  Sandstone locally contains thin lenses of feldspar and chert grit.  Mudstone commonly banded and finely cross-bedded.
Graptolites of Early Cretaceous age (Albian) age in adjoining Nulato quadrangle.  Not sure what unit though (Ks on pub. map but this doesn't match)
Kn
Nonmarine shale, siltstone and sandstone
Nonmarine deposits of drak-gray to olive-gray micaceous shale and siltstone, and light-olive-gray to yellowish-orange, fine- to coarse-grained, crossbedded sandstone.  Massive sandstone beds near base of unit.  Coarse detrital fraction of sandstone chief
Abundant, well preserved flora.
Marine shale and siltstone
Littorial and offshore marine deposits of dark-gray shale and siltstone interbedded with subordinate dark-greenish-gray fine-grained sandstone in lower part and light-olive fine- to coarse-grained crossbedded sandstone in upper part.  Volcanic conglomera
Widespread occurrence of Inoceramus altiflummis (McLearn) of Early Cretaceous (Albian) age
Ksse
Knm
Undifferentiated sedimentary rocks
Undifferientiated units Km and Kn, western part of map.
Kms
Volcanic graywacke conglomerate
Volcanic graywacke conglomerate and mudstone
Granitic rocks
Granitic rocks of acidic and intermediate composition  Chiefly syenite at Roundabout Mountain and albite granite on Huslia River-Derby Creek divide.
KJv
Cretaceous and Jurassic(?)
Chiefly porphyritic pyroxene andesite and trachyandesite flows, andesitic crystal and lithic tuff, and massive andesite breccia, agglomerate, and conglomerate.  Commonly altered and therefore pale green.  Interbedded dark-greenish-gray tuffaceous graywac
Buchia subokensis of earliest Cretaceous age in interbedded sedimentary rocks.
Pzs
Limestone and schist
DCd
Pzl
Pzld
Pzls
Undifferentiated alluvial, colluvial, and eolian terrace and slope deposits
Chiefly silt and very fine sand.  Includes extensive loess deposits
MD002
Medfra
Silt, sand, and gravel
Largely silt and sand but probably includes abundant gravel along Tonzona River.
Sheetlike dune fields of tan fine- to medium-grained eolian sand, locally overlain by peat and loess
Unsorted bouldery till
QTg
Gravel deposits on Jones Creek
Quaternary-Tertiary
Moderately dipping gravel exposed on Jones Creek near Nixon Fork fault, approximately 25 m thick
TKn
Volcanic rocks of the Nowitna River area
Latest Cretaceous, Earliest Tertiary
Chiefly subaerial flows of trachyandesite, basaltic andesite, and basalt.  Subordinate intercalated flows and tuffs of rhyolite and dacite.
63 to 64 Ma
TKvi
TKnr
Volcanic rocks of the Nowitna River area -- rhyolite
Latest Cretaceous, earliest Tertiary
Altered rhyolite domes and associated rhyolitic tuff and breccia.
Mafic to intermediate Volcano-plutonic complexes
Altered basalt, andesite, and trachyandesite porphyry flows and hypabyssal intrusive bodies.  Altered mafic and intermediate crystal and lithic tuffs.  Subordinate olivine basalt and dacite flows.
K-Ar ages of 65-71 Ma
TKcm
Mafic to intermediate volcano-plutonic complexes -- monzonite
Small bodies of monzonite, quartz monzonite, and granodiorite
Granite
White to light gray, fine- to coarse-grained biotite granite.
63-71 Ma
Includes monzonite, quartz monzonite, quartz monzodiorite, and monzodiorite.  Subordinate monzogabbro and gabbro
66-70 Ma
Volcanic rocks of Nixon Fork-Upper Sulukna River area
Sills, dikes, flows, and plugs of rhyolite, dacite, and trachyandesite.
62-67 Ma
TKs
Volcanic rocks of the Sischu Mountains
Light-gray to purplish-red banded rhyolite and dacite subaerial flows and domes, locally containing interlayered breccia and tuff.
66-71 Ma
TKsc
Conglomerate, sandstone, and lignite
Conglomerate, sandstone, and lignite.
TKcg
TKsa
Dike-like body of dark-brown to gray andesite porphyry.
Undifferentiated gabbro
Devonian to Tertiary
Sills, dikes, and small plutons of gabbro intruding rocks of early Paleozoic and preCambrian(?) age
Ksu
Undifferentiated shale, siltstone, and sandstone
Cretaceous, early and late [possible Permian(?)]
Chiefly dark-gray carbonaceous, largely nonfossiliferous shale, siltstone, and very fine-grained sandstone.  Includes massive limestone conglomerate of uncertain age and stratigraphic affinities.  Conglomerate clasts consist of Paleozoic limestone and un
reworked Paleozoic
Chiefly fine- to coarse-grained, greenish-gray to gray, thinly cross-bedded "salt and pepper" sandstone and quartz-chert pebble conglomerate.  Poorly exposed interbeds of dark shale and siltstone.
locally abundant plants and fresh and brackish water mollusks
early Late Cretaceous (Cenomanian)
Fine- to medium-grained, dark-greenish-gray, thinly cross-bedded, fossiliferous sandstone and poorly exposed dark-gray siltstone and shale.
Inoceramus concentricus, and I. pictus
Quartz-carbonate sandstone and pebbly mudstone
Early Cretaceous (Valanginian, Hauterivian, Barremian, Aptian)
Fine- to coarse-grained quartz-carbonate sandstone and conglomerate, quartzose limestone and dark-gray pebbly mudstone and siltstone.
Buchia sublevis, B. crassicolis, Cylindroteuthis, Inoceramus, Acroteuthis, Tropaeum
Ksm
earliest Cretaceous
Poorly sorted fine- to coarse-grained graywacke, sandstone, grit, and pebble to cobble conglomerate composed chiefly of volcanic rock and chert detritus; interbedded dark mudstone.
Inoceramus
JTrt
Cherty tuff, crystal and lithic tuff, and volcanic breccia
Triassic and possible early Jurassic
Dark-greenish, very fine grained cherty tuff grading into greenish-gray radiolarian chert.  Fine to coarse-grained dark greenish-gray crystal and lithic tuff.  Volcanic breccia and conglomerate composed of poorly sorted clasts of mafic volcanic rocks and
Radiolaria and conodonts
JTrta
Trs
Spiculite and sandy limestone
Late Triassic (Norian)
Dark-gray banded spiculite and chert, yellowish-orange-weathering sandy fossiliferous limestone and conglomerate and dark-gray shale
Monotis ochotica, M. of M. scutiformis, Halobia, Heterastridium
Trsl
Ps
Sandstone, sandy limestone, and conglomerate
Permian
Fine- to coarse-grained yellowish-orange-weathering sandstone, limy sandstone, siltstone, and conglomerate.
Kuvelousia, Spiriferella, Waagenoconcha
PDsc
PMc
Chert and limestone
Pennsylvanian and Mississippian
Chiefly greenish-gray, dark-gray to black, and red radiolarian chert.
Radiolarians
TPMcl
Limestone and sandstone
Mississippian
Lenticular beds of fossiliferous limestone having subordinate beds of sandy limestone, chert grit, and arkosic sandstone.
Conodonts and foraminifera
DOsl
Shaly limestone
Ordovician to Middle Devonian
Dark-gray to grayish-orange finely laminated limestone and dolomitic limestone.  Suborbinate laminated dolomite, dark chert, and silicous siltstone.  Interpreted as deep-water facies of Osl, Od, and DSl carbonate units.
Conodonts
DSl
Reefy limestone and dolomite
Late Silurian, Early Devonian (Siegenian-Emsian), early Late Devonian (Frasnian)
Unit composed of a lower sequence of dolomite containing ostracodes of probable Late Silurian age, a middle sequence of mixed limestone and dolomite having favostid reefs and shelly fossils of probable Early Devonian age and an upper sequence of Amphipor
ostracodes, favostid, Ampihpora, Smithiphyllum
DSwc
Sls
Thin-bedded limestone
Silurian (latest Llandoverian to early Wenlockian)
Dark-gray to black platy limestone and limy shale.
graptolites
Spf
Od
Massive dolomite and limestone
Middle to Late Ordovician (White Rockian to Maysvillian)
Light-brown to dark-gray massive dolomite and limestone cyclically interbedded with shallow-water yellowish-orange-weathering algal and lime mudstone.
Gastropods, corals, brachiopods, ostracodes, conodonts
Osl
Silty limestone and siltstone
Early Ordovician
Chiefly yellowish-orange-weathering, thin-bedded, shallow-water, silty limestone and limy siltstone.
Conodonts, trilobites, gastropods, cephalopods
Chert and phyllite
early Paleozoic
Banded light-gray to black sooty impure radiolarian chert, green talcy phyllite and slate, thin-bedded shaly limestone, and calcareous quartzite.
SCpl
Quartzite, grit, and argillite
early Paleozoic or preCambrian
Fine- to coarse-grained quartzite, quartz grit, quartz-feldspar grit, and argillite grading upward in to very fine grained quartzite, argillite, calcareous argillite, phyllite, and chert.
CZw
Sheared and foliated quartz and quartz-feldspar grits and quartzite intercalated with quartz-muscovite-chlorite and quartz-muscovite-biotite schists.  Subordinate phyllite, thin limestone, and metachert.
276 Ma K-Ar muscovite and 421 Ma K-ar(?) hornblende on intrusion (?) to unit.
YZns
PzpCv
Metavolcanic rocks
Tan, light-gray, pink, and green banded fine-grained felsic volcanic rocks having well-developed foliation.  Cheifly porphyry composed of large phenocrysts of embayed quartz and plagioclase in a very fine grained quartzo-feldspathic groundmass which has
YZnv
PzpCc
Calc-shist
Light to medium-gray calc-schist and thin-bedded schistose impure marble  White to light-gray, fine-grained massive sandy marble.  Subordinate quartz-mica schist.
YZnc
PzpCp
Chiefly pelitic and quartzose metasedimentary rocks of greenschist facies.  Light-gray micaceous quartzite and greenish quartz-chlorite-muscovite schist grading into dark-gray quartz-muscovite-biotite-garnet schist.  Subordinate calc schist and marble.
K-Ar mica ages from 274-514 Ma, correlatives as old as 921 Ma
Surficial deposits
Glacial drift of several ages, including moraines, outwash, and lake deposits; alluvium and colluvium.  All mainly consist of unconsolidated gravel, sand, silt, and clay.
HE002
Healy
Thd
Hornblende dacite
Pliocene
Subvolcanic intrusive rocks (hornblende dacite) of Jumbo Dome
K-Ar hornblende age of 2.79 Ma
Tn
Nenana gravel
Pliocene and Miocene
Poorly consolidated, buff to reddish-brown, fluvial sequence of pebble- to boulder-conglomerate and coarse-grained sandstone with interbedded mudflow deposits, thin claystone layers, and local thin lignite beds.
Coal-bearing rocks
Miocene to Eocene
Unit mostly comprises in ascending order, the Healy Creek, Sanctuary, Suntrana, Lignite Creek, and Grubstake Formations.  Coal-bearing rocks comprise terrestrial cyclical sequences, having varying proportions of siltstone, claystone, mudstone, shale, gen
Floral assemblages
Sedimentary rocks
Miocene? to Paleocene?
Poorly consolidated, fluviatile sequence of dark-gray shale, yellowish-gray sandstone, siltstone, and pebble conglomerate (consisting of dominantly gray quartz and black chert clasts).
Indeterminate plants
Tsu
Tvv
Volcanic rocks -- volcanic flows, pyroclastic rocks, and subordinate subvolcanic intrusive rocks
Oligocene to Paleocene
Subaerial flows and associated pyroclastic rocks ranging in composition from rhyolite to basalt.  Tend to be dominantly moderately altered rhyolite and basalt, but andesite, dacite, and latitie also occur
K-Ar sanidene age of 53.9 Ma on rhyolite
Tvu
Tvim
Volcanic rocks -- mafic subvolcanic intrusive rocks
Dikes and small hypabyssal bodies of dark-gray basalt, diabase, and subordinate andesite
K-Ar age of 54.7 Ma on basalt dike
Thm
Tvif
Volcanic rocks -- felsic subvolcanic intrusive rocks
Dikes and small hypabyssal bodies with subordinate associated pyroclastic rocks, of dominantly tan-colored, aphanitic to very fine grained, locally porphyritic rhyolite, quartz latite, latite, and dacite.
K-Ar ages ranging 32.5 to 35.2 Ma on rhyolite
Thf
Tfv
Fluviatile and subordinate volcanic rocks
early Eocene?
Intercalated, fluviatile, only slightly deformed sequence of conglomerate, sandstone, siltstone, and mudstone, and a few interlayed thin flows of basaltic andesite.  Clasts in conglomerate contain Late Devonian conodonts.
Metasequoia occidentalis (Newberry) Chaney
Tcv
Cantwell Formation -- volcanic rocks subunit
Paleocene
Intercalated, moderately deformed sequence of andesite, generally zeolitized basalt, rhyolite and dacite flows, dominantly felsic pyroclastic rocks, a few interbeds of sandstone and carbonaceous mudstone, and a few small bodies of related subvolcanic int
K-ar Hornblende age of 64.6 Ma on dacite, basalt, andesite, and diabase ages ranging from 50.9 (>42.9 min.) to 61.0 (>62.2 min.) Ma
Tcs
Cantwell Formation -- sedimentary rocks subunit
Fluviatile, intercalated sequence, in various proportions, of dominantly polymictic conglomerate, sandstone (including arkose), siltstone, argillite, shale, and a few thin coal beds.  Locally contains thin flows and related tuff layers of mafic to interm
Plant fossils of Paleocene age, including Metasequoia occidentalis (Newberry) Chaney
K-Ar biotite ages  on granitic intrusions were 71.9 and 78.7 Ma, ages of dubious geologic value.
Kcs
Tgr
Wide variety of epizonal granitic rocks, most commonly granite and grandiorite but including tonalite and quartz monzodiorite.
K-Ar ages ranging from 36.7 to 59.8 Ma
Tegr
Tgrv
Granitic and volcanic rocks, undivided
Extensive border zone between rocks of late Tertiary granitic pluton (unit Tgr) and slightly younger, numerous felsic dikes and small subvolcanic intrusive rocks (unit Tvv), as well as small erosional remnants of rhyolite flows capping pluton.
Tiv
TKgr
Granitic and hypabyssal intrusive rocks
Paleocene? and Late Cretaceous
Two small granodiorite plutons of medium-grained granodiorite
K-Ar biotite ages of 71.9 and 78.7 Ma, probably of dubious geologic meaning (very low K2O in biotite)
TrPzvs
Volcanic and sedimentary rocks of the Talkeetna superterrane
Triassic and Paleozoic
Appears only in cross-sections
Kvb
Basaltic subvolcanic rocks
Dark-gray to black, porphyritic basalt, occurring in dike swarms.  Only know to intrude preCambrian and Paleozoic rocks (units PzpCp and Dmb).
K-Ar hornblende age of 79.1 Ma on basalt
MDt
Totatlanika Schist
Early Mississippian to Middle Devonian
Predominantly metavolcanic and metavolcaniclastic (both felsic and mafic), and subordinate amounts of intercalated metasedimentary rocks such as black pelitic schist, and at one lacality a thin interbed of fossiliferous marble.
Crinoids, gastropods, Syringopora sp., conodont Polygnathus sp.
MDt?
Totatlanika Schist?
Dmf
Felsic metavolcanic rocks
Late Devonian?
Massive, thick section of generally dark- to medium-gray, fine- to medium-grained schists and locally phyllites, with relict phenocrysts of quartz, orthoclase, and plagioclase.
Conodonts from interbeds of unit Dmb
Dyv
Dmb
Metabasalt and subordinate metasedimentary rocks
Late Devonian
600 m thick intercalated sequence of schistose and phyllitic, generally medium to dark greenish-gray, fine-grained and massive metabasalt; dark gray to black, generally fine-grained carbonaceous pelitic schist and phyllite and associated metasiltstone; a
Conodonts Palmatolepis sp., Iciodus sp., Polygnathus sp.
K-Ar muscovite age of 114.6 Ma on black phyllite
Pzsc
Dms
Metasedimentary rocks
Intercalated, generally thinly bedded, locally laminated, thick, marine sequence of dark-gray to black, carbonaceous, fine-grained, carbonaceous, fine-grained pelitic schist or phyllite; dark-gray, fine-grained, carbonaceous metasiltstone (quartzose phyl
Amphipora? sp., Disphyllum? sp., Grypophyllum? sp., Phillipsastraea? sp., Tabulophyllum? sp.
Pzk
Keevy Peak Formation
Intercalated sequence of fine- to medium-grained quartz-sericite or muscovite schist, fine-grained black quartzite, black carbonaceous pelitic schist and phyllite, stretched pebble conglomerate, greenish-gray or purple schist and slate, and a few thin ma
Pelitic and quartzose schist sequence [old, abandoned Birch Creek Schist]
early Paleozoic and preCambrian?
Intercalated in various proportions: medium- to fine-grained, generally medium-gray quartz-sericite and (or) muscovite pelitic schist; fine- to medium-grained, medium-gray quartzite; quartz-sericite and (or) muscovite-calcite pelitic schist; fine-grained
PzZaqs
Trcs
Calcareous sedimentary rocks
Late Triassic; middle? Norian to late Karnian
A generally thin-bedded, commonly cross-bedded, carbonaceous, dark- to medium-gray, marine, intensely deformed thick sequence of intercalated calcareous shale, argillite, sandstone, siltstone, and sandy to silty and argillaceous limestone.  Sequence also
Conondonts: Neogondolella polygnathiformis, Epigondolella primitia, also Monotis cf. M. subcircularis, Chrondites sp.
Dy
Yanert Fork sequence
Intensely deformed, thick marine sequence of dominantly metasedimentary and metavolcanic rocks.  Bulk of sequence is dark-gray to black carbonaceous shale with intercalations of thin-bedded, commonly bioturbated, medium- to dark-gray, normally graded, bo
Radiolarians, conodont Palmatolepis sp.
Kva
Andesitic subvolcanic rocks
Two large sills or dikes consisting of altered, medium-greenish-gray, porphyritic hornblende andesite.
K-Ar on hornblende of 97.3 Ma
KJf
Flysch sequence
Early Cretaceous and Late Jurassic
Monotonous, intensely deformed and locally highly metamorphosed, probably several thousand of meters thick, flyschlike turbidite sequence.  Consists of dark-gray to black argillite; fine- to coarse-grained, generally dark-gray polymict pebble conglomerat
Fossils sparse but age considered well controlled
K-Ar reset ages yielded Late Cretaceous and Tertiary
KJfk
Overthrust flyschlike rocks
Early Cretaceous -- Late Jurassic
Same as unit KJf, mapped separately for structural reasons.  Monotonous, intensely deformed and locally highly metamorphosed, probably several thousand of meters thick, flyschlike turbidite sequence.  Consists of dark-gray to black argillite; fine- to co
KJcg
Conglomerate, sandstone, siltstone, shale, and volcanic rocks
Intercalated sequence of polymictic pebble and cobble conglomerate, sandstone, siltstone, shale, and flows and dikes of andesitic to latitic feldspar porphyry.
Buchi spp.
Trvs
Metavolcanic, metavolcaniclastic, and subordinate metasedimentary rocks
Late Triassic; late Norian
Consists of intercalated sequences several hundreds of meters thick, ocurring as thrust slices.  Most common rock type is dark-greenish-gray aphanitic metabasalt contiaing numerous amygdules and occurring in thick, commonly pillowed massive flows.  Metav
Monotis subcircularis, Heterastridium sp.
Trmm
Trcn
Chitistone and Nizina Limestones, undivided
Late Triassic; early Norian and Late Karnian
consists variably of medium- to thick-bedded, medium-gray weathering, brownish-gray lime mudstone with chert nodules and streamers, or medium- to thin-bedded, commonly thinly laminated, dark-gray to dark-brownish-gray lime mudstone, or thin- to medium-be
Halobia sp. and several conodonts
JTrlm
Trn
Nikolai Greenstone
Late and (or) Middle Triassic
An over 3,000-m-thick, slightly metamorphosed sequence of massive basalt flows with subordinate amounts of intercalated basaltic tuff and breccia, some bedded volcaniclastic rocks such as pebble conglomerate, sandstone, and siltstone, and possibly a few
Halobia superba collected from an interbed?
TrPam
Metasedimentary rocks sequence
Middle Triassic to Late Pennsylvanian
Lower and principal part of section (700-m-thick) consists of black argillite with laminae and thin interbeds of volcanic sandstone and lesser amounts of thin-bedded crinoidal limestone, apparently turbidite deposits forming discontinuous interbeds as mu
Crinoids, conodonts, radiolaria
Pe
PPav
Andesitic volcanic rocks (Correlated with Tetelna Volcanics)
Early Permian? and Pennsylvanian
Over 2,000-m-thick sequence of gray-green massive volcanic flows, breccias, and subordinate volcaniclastic rocks, all largely andesitic in composition.
Pat
Kgr
Late and Early Cretaceous
Most commonly tonalite but granodiorite, quartz diorite, diorite, and quartz monzodiorite.
K-Ar age range from 105 to 49 Ma, most 50 to 70 Ma thought to be reset.  For NSAclass coding, ages less than 85 Ma = 2460, ages 85-110 Ma = 2470, all others = 2410
KJum
Early Cretaceous or Jurassic
Dark greenish- or brownish-gray, coarse- to medium-grained, plagioclase-bearing ultramafic that occurs in a small, sill-like intrusive
Jum
Kgrt
Tourmaline-bearing granite
Late or Early Cretaceous
Medium- to fine-grained, tourmaline bearing granite with a granitic to seriate texture.
Kgt
Jgb
Alkalic gabbro
Extremely heterogeneous series of alkali gabbros, ranging from mafic theralites through essexites and monzogabbros into monzodiorites and monzonites.
K-Ar age on biotite and hornblende 132 and 146 Ma
Jmu
Dmg
Metagabbro
Dark greenish-gray, fine- to medium-grined, well-foliated gabbro.
KJa
Argillite, chert, sandstone, and limestone
Dark-gray argillite, dark-gray to greenish-gray bedded chert, thick-bedded gray sandstone, thin-bedded gray sandstone, and rare thin beds of shelly limestone.
Radiolarians, Inoceramus sp., Buchia sublaevis
KJfn
JTrrs
Red and brown sedimentary rocks and basalt
Early Jurassic and Late Triassic
Maximum thickness of more than 2,000m.  Basal part consists of a red-bed sequence of sandstone, siltstone, argillite, and conglomerate, with a few thin interbeds of brown fossiliferous sandstone, pink to light-gray dense limestone, and intercalated basal
JTrsu
Trlb
Limestome and basalt sequence
Late Triassic; Norian?
Interlayed sequence, at least several hundreds of meters thick, of limestone, partly recrystallized to marble, and flows of altered amygdaloidal basalt.
Spondylospira(?) sp.
Trr
Red beds
Late Triassic
About 500 m of red sanstone, siltstone, argillite, and conglomerate, similar to red beds of unit JTrrs
TrDv
Volcanogenic and sedimentary rocks
Early Triassic to Late Devonian
Heterogeneous intercalated sequence over 500m thick, of greenish-gray to black tuffaceous chert, volcanic conglomerate, lesser amounts of maroon volcanic mudstone, breccia composed largely of basaltic detritus, laminated flyschlike graywacke and shale, l
Ammonites, conodonts, brachiopods
Dsb
Serpentinite, basalt, chert, and gabbro
Tectonically intermixed assemblage a few hundreds of meters thick largely of sheared serpentinite.  Remaining component rocks occur in varying proportion is in lenticular and podiform tectonic blocks as much as several hundred meters in extent.
Dmgs
KJfl
earliest Late Cretaceous (Cenomanian) to Late Jurassic
Lithologically identical to rocks of unit KJf:  Monotonous, intensely deformed and locally highly metamorphosed, probably several thousand of meters thick, flyschlike turbidite sequence.  Consists of dark-gray to black argillite; fine- to coarse-grained,
Only mapped flysch unit to have fossils as young as earliest Late Cretaceous (Cenomanian).
Crystal tuff, argillite, chert, graywacke, and limestone
Late Jurassic to Late Triassic?
Four-fifths of the sequence is composed of massive cliff-forming crystal tuff, while remaining rocks form a narrow belt along western margin of unit.  Contact between two parts of sequence may be tectonic.  Crystal tuff is light- to dark-gray, locally ha
Radiolarians (of Callovian to early Tithonian age [Late Jurassic]), Artoasteroceras jeleskyi, Paltechioceras (Orthechioceras?) sp., Weyla sp. indicating a late Sinemurian (Early Jurassic) age
JTrct
Trcg
Conglomerate and volcanic sandstone
Lower part (40-50 m) of three unit division consists of cobble to boulder conglomerate composed of green volcanic rocks and red radiolarian chert clasts.  Middle part, 40 to 50 m thick, composes of finer grained volcanogenic (andesitic?) conglomerate con
Permian radiolaria in lower part in clasts; Heterastridium sp. (Late Triassic, late Norian) in middle
DOs
Sedimentary sequence
Middle Devonian to Ordovician
Medium- to dark-gray, thinly graded bedded to laminated, medium- to fine-grained sandstone; dark-gray to black argillite; intercalated layers, a few tens of meters thick, of dark-gray, generally thinly bedded, locally thick-bedded limestone and dark-gray
Gastropods.  Middle Devonian fossils reported from massive limestone (ls).
JCmd
ls (DOs)
Limestone (Sedimentary sequence)
Middle Devonian (to Ordovician)
Approximately 200-m-thick interbed of medium- to light-gray, massive, finely to medium-crystalline, partly  dolomitic limestone (mapped separtely as unit 'ls').  Part of unit DOs.
Middle Devonian fossils reported from massive limestone (ls).
DSml
Trbd
Basalt, diabase, and subordinate sedimentary rocks
Late Triassic; Karnian and Norian
Submarine sequence of several hundred, perhaps several thousand meters thick of basalt flows, mostly pillowed, with associated sills and dikes of diabase and gabbro.  Subordinate interbedded sedimentary rocks are dark-gray to dark-grayish-green, fine-gra
haboloid bivalve, radiolaria
TrPas
Flyschlike sedimentary rocks
Late Triassic to Pennsylvanian
Intensely folded marine sequence of at least several hundred meters of dark-gray to black, massive to thin-bedded, flyschlike rocks: conglomerate, sandstone, siltstone, argillite, a few thin interbeds of impure limestone and near top of section, thin int
Abundant trace fossils and displaced bryozoans, echinoderm fragments, rare brachiopods, corals, crinoids, condonts
Melange south of McKinley fault
Late and (or) Early Cretaceous
Fault-bounded tectonic and probably sedimentary melange of Paleozoic and upper Mesozoic rocks  Three distinct suites:  1)  Medium- to thin-bedded, greenish-gray to tan-colored, locally black, cherty tuff, chert, argillite, and fine-grained volcanic sands
Radiolaria, conodonts in cherty tuffs (Late? Devonian to Missisppian).  Megafossils and conodonts from limestone (Silurian to Middle Devonian)
Melange
Kmar
Kmn
Melange north of McKinley fault
Fault-bounded tectonic and probably sedimentary melange of Paleozoic and upper Mesozoic rocks  Four disparate, intricately intermixed  and pervasively sheared rock suites:  1)  Blocks of medium-gray, medium-grained limestone of Silurian(?) to Devonian ag
Radiolaria, Buchia sp. (also see mnl)
msl (Kms)
Limestone of Melange south of McKinley fault
Lenses and elongate blocks of medium-gray, generally medium-bedded and rarely massive, fine- to medium-grained fossiliferous limestone mapped separately as unit 'msl' but is unit 3 of unit KMs, which is a fault-bounded tectonic and probably sedimentary m
Labechia sp., Favosites sp., Dendrostella? sp., massive stromataporoid, and conodonts (Silurian to Middle Devonian)
TrSl
mnl (Kmn)
Limestone of Melange north of McKinley fault
Parts 1 and 2 of unit Kmn, a fault-bounded tectonic and probably sedimentary melange of Paleozoic and upper Mesozoic rocks.  Parts are:  1)  Blocks of medium-gray, medium-grained limestone of Silurian(?) to Devonian age; and 2) Blocks of medium-gray, med
Conodonts, Sagenites?, Tryplasma sp., Lyrielasma? sp., Zelophyllum? sp.,Clavidictyon sp., Ampipora sp., Megalodus sp., Mysidia sp., Belemnite sp. interdeterminate, Cladopora sp., Coenites? sp., coral, molluscs, brachiopods, conodonts, crinoid fragments
mno (Kmn)
Part 4 of unit Kmn, a fault-bounded tectonic and probably sedimentary melange of Paleozoic and upper Mesozoic rocks  Consists of a poorly exposed small sliver of serpentinized ultramafic rocks, altered basalt, green and maroon tuff, and recrystallized ch
mlu
Ql
Young and old landslide deposits
Chiefly debris avalanches and large block glides in areas of steep slopes
TL002
Talkeetna
Qau
Alluvium, undivided
Chiefly boulders, gravel, and sand with local areas of silt and clay.  Alluvium on active flood plains, older alluvium on terraces of major streams, alluvial fans, outwash, swamp, marsh, and bog deposits, and alluvial deposits on broad pediment surfaces.
Qr
Active and recently active rock glaciers
Chiefly rubble and diamicton
Glacial deposits -- Alaskan glaciation
Chiefly rubble and diamicton.  Includes end and lateral moraines.
Qn
Glacial deposits -- Naptowne glaciation
End, lateral, and ground moraine, postglacial alluvial, pond, and swamp deposits, fluvial glacial deposits of all stages of Naptowne glaciation and glaciolacustrine deposits formed during Knik and Naptowne glaciations
Qk
Glacial deposits -- Knik glaciation
Well-developed end and lateral moraine, shown only northwest part of quadrangle.
Qe
Glacial deposits -- Eklutna glaciation
South of the Alaska Range, lateral and ground moraine have subdued geomorphic expression and include alluvial, swamp, marsh, and bog deposits.  North of the Alaska Range, end and lateral moraines are relatively fresh.
Qpe
Glacial deposits -- pre-Eklutna age glaciations
Subdued lateral(?) and ground moraines on north side of Alaska Range, although glacial erratics and well-modified drift on top Yenlo Hills are probably also deposits of this glaciations.
Tc
Possible Oligocene and Miocene
About 30 m of subituminous coal, with individual beds up to 9 m thick.  Coal-bearing rocks contain interbeds ferruginous siltstone and silty shale.
Continental sedimentary rocks
Tertiary, Paleocene
Chiefly medium- to dark-gray phyllitic shale, shale, sandstone, grit, and conglomerate with minor carbonaceous shale and tuffaceous sandstone.
Metasequoia
KJb
Pillow basalt
Early Cretaceous and Jurassic(?)
Dark-greenish-gray elongate bodies of massive-weathering, resistant pillow basalt.  The unit includes interbeds and lenses of mudstone, shale, and siltstone.  The basalt locally includes gabbro which may represent its feeder source.
JTrtv
KJs
Undivided marine sedimentary rocks
Moderate- to deep-water, intertonguing marine sedimentary rocks consisting chiefly of gray to black phyllite, argillite, graywacke, and siltstone which are in part turbidite deposits; lesser amounts of gray, green, and red chert, conglomerate, grit, and
belemnites, Buchia, and occasional Inoceramus of Valanginian to Barremian age)
Pzsl
Shale and limestone
Early Paleozoic?
Marine sedimentary rocks that typically form a thin- to medium-interbedded sequence of black, sooty, carbonaceous, and calcareous shale, dark-gray calcareous siltstone, medium- to dark-gray limestone, and minor gray quartzite.  Shale locally amounts to a
Pzsv
Quartzite, semischist, and metavolcanic rocks
early Paleozoic? or possibly late preCambrian
Tan to light-greenish-gray, low-grade (greenschist facies), regionally metamorposed quartzite, quartz semischist, quartz grit, metavolcanic rocks, and minor conglomerate, limestone, phyllite, and quartz-muscovite schist.  Isoclinally folded.
Tmt
Tonzona pluton
Early Tertiary
Small composite biotite-muscovite granite pluton
Tpgr
Undivided intrusive rocks -- dikes
Early Tertiary or Late Cretaceous
Intermediate altered porphyry dikes -- most not shown on map as too small
MzPzg
Gabbro and quartz diorite
Mesozoic and (or) Paleozoic
Dark-green, rust-weathering coarse-grained altered gabbro and minor quartz diorite.
MzPzu
Serpentinite
Orange- to light-brown-weathering, light- to dark-green, fault-bounded body of serpentinite and minor talc schist.
MzZum
Tk
Kenai Group, undivided
Fluvial sedimentary rocks correlative with estuarine and nonmarine clastic sedimentary Tertiary formations assigned to the Kenai Group.
Tps
Sterling(?) Formation
Orange, light-tan, or light-gray, massive-bedded conglomerate, distinguished from conglomerate in the Tyonek Fm by color, relative coarseness, and clast lithology.  As much as 770 m thick.
Tsf
Tts
Tyonek(?) Formation -- Sandstone member
Miocene
Approximately 80 percent sandstone, 20 percent siltstone and claystone, and less than 1 percent conglomerate, coal, and volcanic ash.  Occurs in repetitive cycles 7- to 23-m-thick.
Tty
Ttc
Tyonek(?) Formation -- Conglomerate member
At least 40 percent conglomerate, 20 percent sandstone, and less than 40 percent siltstone, claystone, and coal.  Conglomerate is light-brown, light-gray, or bluish-gray and poorly indurated.  Sandstone is coarse, poorly sorted and pebbly, and very poorl
Tvs
Undivided volcanic and sedimentary rocks
Interbedded tuff, mafic volcanic flows, sandstone, shale, and minor calcareous mudstone.  Volcanic rocks are chiefly medium- to coarse-grained greenish-gray crystal lithic lapilli tuff and volcanic rubble flows in units as much as 150 m thick.
Cretaceous and Early Jurassic
Medium- to dark-gray, generally isoclinally folded, thick sequence of lithic graywacke, phyllite, and shale with local lenses of quartz-chert conglomerate.  Minor fossiliferous limestone, radiolarian chert, and red ferruginous sandstone and siltstone.  [
Inoceramus, ammonites, brachiopods, and pelecypods
Pzbs
middle or late Paleozoic
Chiefly dark-greenish-gray massive pillow basalt and petrographically similar coarse-grained pyroxene gabbro and basaltic dikes and sills.  as mapped, includes varying amounts of interstratified agglomerate, flow breccia, aquagene tuff, and thick, chaoti
Pzv
Volcanic and sedimentary rocks
Dark-greenish-gray massive-weathering mafic volcanic rocks that include pillow basalt, breccia, agglomerate, tuff, and massive basalt flows.  Volcanic rocks commonly contain interbeds of black phyllite, chert-pebble conglomerate, light-green tuff, and gr
Pzvs
Pad
Conglomerate of Mount Dall
Middle Pennsylvanian
Dark-brown to yellowish-brown-weathering sequence of conglomerate, sandstone, siltstone, and shale mainly of continental origin that forms a broad, open, east-plunging syncline.  Unit is chiefly massive lenticular beds of conglomerate and sandstone with
Limestone clasts in conglomerate contain Middle Devonian(?) fossils.  Shale and sandstone beds locally contain abundant plant fossils of Middle Pennsylvanian age.
Pzus
Undivided sedimentary rocks
Mississippian, Pennsylvanian, and (or) Devonian
A depositionally and structurally complex terrane of chiefly marine flysoid sedimentary rocks which include: 1) trench assemblages characterized by terriginous turbidites, cherty pelagites, and basaltic pillow lavas; 2) slope and shelf assemblages that i
Fossils of varying late Paleozoic ages
Middle and Late Devonian
Thin-bedded gray micrites grading upward into fossiliferous, massive to reefoid, biostromal beds of colonial rugose corals and massive stromatoporoids.
Conodonts of Late Devonian; abundant coral and shelly faunas of late Middle and early Late Devonian; locally late Early or Middle Devonian
DSmdl
Pzp
Phyllite
Dark-gray phyllite, phyllitic shale, and argillaceous siltstone.
Sl
Silurian
Light-gray to light-brown massive-weathering marbleized limestone and local areas of thin-bedded to laminated limestone.
Graptolites, dasycladacean algae, corals
Oc
Chert and shale
Early to Middle Ordovician
Chaotically folded allochthonous sequence of interbedded graptolitic shale and chert and minor sandstone and siltstone.
Graptolites
Pzd
Sedimentary rocks of Dillinger River (limey)
Thick sequence of sedimentary rocks consisting of an undetermined thickness of interbedded lime mudstone and shale, more than 900 m of apparently unfossiliferous deep-water, well-bedded lime mudstone (micrites), and at least 900 m of interbeeded sandston
Cardiolacea of late Wenlockian (Silurian) age, conodonts of Silurian age.
Tf
Foraker pluton
Eocene
Medium-grained, equigranular biotite and hornblende granodiorite.
K-Ar? of 38 MA
Toem
Tm
McKinley Sequence -- McKinley pluton
Medium- to coarse-grained, hypidiomorphic-granular biotite granite.
Tmc
McKinley Sequence -- Cathedral pluton
Medium- to coarse-grained, hypidiomorphic-granular biotite and biotite-muscovite granite and minor phases of biotite-hornblende granodiorite.
Tmk
McKinley Sequence -- Kahiltna pluton
Two bodies, southwest is fine- to coarse-grained, hypidiomorphic-granular biotite and biotite-muscovite granite and granodiorite.  Northeast body is medium- to coarse-grained, hypidiomorphic-granular biotite-muscovite granite.
Tmr
McKinley Sequence -- Ruth pluton
Three bodies, Chulitna body is medium- to coarse-grained, weakly foliated, hypidiomorphic-granular biotite granite.  South body is coarse-grained, hypidiomorphic-granular biotite granite and granodiorite.  North body is medium- to coarse-grained, hypidio
Te
Granodiorite of Mount Estelle
Medium-grained, hypidiomorphic-granular biotite-hornblende granodiorite.  Tourmaline is a characteristic accessory mineral.
K-Ar ages on hornblende of 65 and 66 Ma
Thgd
Tcp
Composite plutons
Average composition is quartz monzonite but ranges from peridotite to granite.
K-Ar ages range from 64.6 and 67.4 Ma
Unidivided intrusive rocks
Late Cretaceous or Tertiary
Probably range in composition from granite to tonalite
Mesozoic or Paleozoic
Dark-gray to greenish-gray dikes and sills ranging in composition from basalt to granodiorite.
MzPzd
Undivided dunite and serpentinite
Alpine-type ultramafic rocks and minor talc schist.  Chromite-bearing dunite in sills.
JTrsv
Chulitna sequence -- Sedimentary and volcanic rocks
Jurassic to late Triassic
Massive cliff-forming outcrops of argillite, radiolarian chert, siltstone, minor pillow basalt, and impure micritic limestone.
JTrvs
Chulitna sequence -- Volcanic and sedimentary rocks
Early Jurassic to late Paleozoic
Distinctive light-green to maroon volcaniclastic rocks that range from tuffaceous shale to a quartz-pebble conglomerate having a tuffaceous matrix.  Commonly contain interbeds of massive micritic and bioclastic limestone, minor chert, argillite, rust-wea
Thecosmilia, Heterastridium, and Septocardia(?) of Late Triassic (Norian) age
Chulitna sequence -- Limestone and basalt
Limestone and basalt which grades southwestward into interbedded gray limestone, dark-green pillow basalt, massive and locally semischistose basaltic tuff, calcareous sandstone, and minor black chert and silty limestone.
Monotis subcircularis, Heterastridium, and Cassianella of Late Triassic (Norian) age
Alluvial deposits
Holocene
Chiefly unconsolidated sand and gravel.  Flood-plains, fans, and cones.  Oldest deposits may be outwash.
MH002
Mount Hayes
Qfl
Fluviolacustrine deposits
Chiefly consisting of sand, silt, and clay.  Lake, pond, and low-gradient streem deposits.
Colluvial deposits
Chiefly rubble, gravel, sand, silt, and clay.  Talus and other slope debris deposits, also includes alluvium of minor streams, and locally glacial, rock glacier, and mass-wasting deposits.  May include older glacial drift and locally grades into glacial
Qam
End and lateral moraines of Alaskan glaciation
Qwm
End and lateral moraines of Wisconsin glaciation
Holocene and Pleistocene
Poorly sorted and unstratified till of unconsolidated sand and gravel.  Chiefly rubble and diamicton, local sand and gravel.
Qwf
Glaciofluvial deposits of Wisconsin glaciation
Moderately well-stratified layers and lenses of well-rounded gravel with a matrix of silt and sand.  Poorly to moderately well sorted with lenses of well-sorted sand locally.
Qog
Drift of older glaciations
Pleistocene
Glacial deposits of subdued geomorphic expression, probably of early Wisconsin or Illinoian age occurring beyond limit of Wisconsin moraines.  At higher elevations, chiefly unconsolidated diamicton and boulder deposits.  At lower elevations, consist chie
Nenana Gravel
Consists chiefly of poorly cemented conglomerate but includes some sandstone and siltstone.  Clast composition in the MH D-6 quadrangle is (in decreasing order of abundance) schist, quartzite, granitic rocks, gabbro, and metagabbro.  Top of unit is erode
Pliocene, Miocene, and Oligocene
Chiefly brown sandstone and graywacke but includes some interbedded conglomerate and dark argillite.  Generally fault bounded.  Sandstone is fine- to medium-grained, poorly sorted, and contains angular grains.  Composition varies from quartz grains in a
Plants of Oligocene, Miocene, and Pliocene age
Tsj
Sedimentary rocks of Jarvis Creek coal field -- undivided
Chiefly sandstone, mudstone, conglomerate, and coal.  (Unit of Wahraftig and Hickcox, 1955.)
Teriary plant fossils
Tjc
Tsju
Sedimentary rocks of Jarvis Creek coal field -- Upper member
Chiefly dark-gray mudstone and sandstone containing scattered coal beds.  Maximum estimated thickness is 300 m.
Tsjm
Sedimentary rocks of Jarvis Creek coal field -- Middle member
Chiefly buff arkosic sandstone containing claystone and scattered coal beds and a prominent coal and shale zone at base.  Maximum estimated thickness is 300 m.
Tsjl
Sedimentary rocks of Jarvis Creek coal field -- Lower member
Chiefly angular quartz sandstone and conglomerate; some claystone and coal.  Maximum estimated thickness is 150 m.
la
Lamprophyre, alkali gabbro, and alkalic diorite
Early Tertiary and Late Cretaceous
Undifferentiated dikes, sills, and small plutons.  Predominantly fine- to medium-grained, panidiomorphic granular to porphyritic texture.
Two clusters of K-Ar ages in the east-central part of quad.  62.9 to 69.2 Ma in the Robertson River area and 69.3 to 107.6 Ma in the Tok River area
TKl
md
Monzonite and diorite
Monzonite and diorite, includes lesser quartz monzonite and quartz diorite.  Undifferentiated dikes, sills, and small plutons.  Fine- to medium-grained, hypautomorphic granular and locally porphyritic
grn1
Granitic unit 1
Early Tertiary and (or) Late Cretaceous
Granite dikes, stocks, and small plutons.  Locally schistose.  Fine- to coarse-grained, hypautomorphic granular and locally porphyritc.
grn2
Granitic unit 2
Granodiorite dikes, stocks, and small plutons.  Locally schistose.  Fine- to coarse-grained, hypautomorphic granular and locally porphyritc.
grn3
Granitic unit 3
Quartz diorite and diorite dikes, stocks, and small plutons.  Locally schistose.  Fine- to coarse-grained, hypautomorphic granular and locally porphyritc.
TKqd
grgr
Granite of Gerstle River
Chiefly biotite granite, include minor quartz diorite.  Fine- to medium-grained, hypautomorphic granular and locally porphyritc.
K-Ar ages of 53.4 and 54.3 Ma
grbc
Granite of Buchanan Creek
Chiefly biotite-hornblende granite, with lesser granodiorite and quartz diorite.  Fine- to medium-grained, hypautomorphic granular and locally porphyritc.
grmh
Granite of Mount Hayes
Chiefly biotite granite, with fine- to medium-grained, hypautomorphic granular texture.
grmr
Granodiorite of Molybdenum Ridge
Chiefly biotite-hornblende granodiorite, with lesser granite and quartz diorite.  Medium-grained, hypautomorphic granular texture, locally porphyritic.
K-Ar biotite and hornblende dates and U-Pb zircon ages ranging from 84 to 93 Ma
grgm
Granite of Granite Mountain
Chiefly biotite-hornblende granite, includes minor quartz diorite.  Fine- to medium-grained, hypautomorphic granular texture.
U-Pb zircon age of 90 Ma
grma
Granite of Macomb Plateau
Chiefly hornblende granite, biotite granite, hornblende-biotite granite, hornblende granodiorite, and minor quartz diorite.  Very fine- to medium-grained, hypautomorphic granular texture, locally porphyritic.
Pb-alpha ages of 90  and 110 Ma (Highly suspect)
grrc
Granite of Rumble Creek
Chiefly biotite-hornblende granite and granodiorite.  Fine- to medium-grained, hypautomorphic granular texture, locally porphyritic.
K-AR hornblende age of 89 Ma
mgb
Gabbro, diorite, metagabbro, metadiorite, metadiabase, and amphibolite
Chiefly hornblende metagabbro, metadiabase, and minor amphibolite.  Undifferentiated dikes, sills, and small plutons.  Metagabbro and metadiabase generally fine- to medium-grained with hypautomorphic granular to diabasic texture, locally porphyritic.  Am
Kmum
gbm
Gabbro of Mount Moffit
Cretaceous?
Gabbro of fine- to medium-grained with hypautomorphic granular to diabasic texture.  Correlative with unit mgb.
lga
Augen gneiss and schist
Mississippian (intrusion age)
Chiefly medium-grained, mylonitic gneiss.  Intensely deformed, exhibiting a strong schistosity showing gentle north or south dips.  Contains diagnostic amphibolite facies minerals and shows retrogression to greenschist facies.
Intrusion from U-Pb zircon age of 333 to 345 Ma from Big Delta quadrangle to north and metamorphism from Rb-Sr ages on multiple phases of 110 Ma
MDyao
lgr
Medium-grained gneissose granitic rocks
Devonian (intrusion age)
Chiefly metagranite but includes some metamorphosed quartz diorite and meta granodiorite.  Relict hypautomorphic granular texture.  Intensely deformed, exhibiting a strong schistosity.  Contains diagnostic amphibolite facies minerals and locally shows re
Intrusion from U-Pb zircon age of 360 Ma and metamorphism from Rb-Sr isochron at 110 Ma
lgs
Pelitic schist and quartzite
Devonian and older
Chiefly fine- to medium-grained, poly-deformed, mylonitic pelitic schist and minor quartzite and calc-schist.  Unit intensely deformed, exhibiting a strong schistosity that dips gently north or south.  Metamorphised to middle to upper amphibolite facies
U-Pb zircon age from qtz-bio-feld schist in Big Delta quadrangle to north was 365 Ma.
PzZysa
mg
Medium-grained granitic gneiss
Chiefly fine- to medium-grained mylonitic gneiss derived from granite, granodiorite, and quartz diorite.  Includes minor augen gneiss.  Texture varies from protomylonitic to mylonitic schist.  Intensely deformed exhibiting strong schistosity.  Schistosit
U-Pb zircon ages about 372 Ma indicate intrusion, Rb-Sr mineral isochron indicates metamorphism at 102 Ma
ms
Metamorphosed pelitic, calcareous, and quartz-feldspar sedimentary rocks
Devonian or older
Chiefly fine-grained, mylonitic, metasedimentary schists.  Quartz-mica schist and lesser calc-schist.  Intensely deformed exhibiting strong schistosity.  Schistosity and parallel composition layering dip moderately southwest and strike northwest.  Metamo
jcg
Fine- to medium-grained gneissose granitic rocks
Devonian (intrusion)
Chiefly schistose metagranodiorite, and augen gneiss.  Intensely deformed exhibiting strong schistosity.
Intrusion age from U-Pb zircon determination of 372 Ma
jcv
Fine-grained schistose metavolcanic rocks and metasedimentary rocks
Devonian (eruption)
Chiefly fine-grained, mylonitic, metavolcanic rocks interlayered with lesser metasedimentary rocks.  Metavolcanic rocks consist chiefly of metamorphosed quartz keratophyre, dacite, and andesite and lesser metarhyodacite and metabasalt derived from fine-g
U-Pb zircon age determinations on metavolcanic rocks yielded ages of 364, 372, and about 375 Ma
jcs
Fine-grained metasedimentary rocks
Chiefly fine-grained, mylonitic, metasedimentary rocks.  Rocks consist of 65 percent quartz-mica schist, 15 percent quartzite, and 5 percent each of chlorite-wihite mica schist, quartz-biotite schist, calc-schist, and marble.  Metamorphism ranges from lo
K-Ar ages on white mica range from 106 to 118 Ma, thought to be metamorphic age rather than cooling age (?)
hgv
Fine-grained schistose volcanic rocks and phyllite
Devonian (extrusion)
Chiefly fine-grained, metavolcanic and metasedimentary phyllonites and blastomylonites.  Metavolcanic rocks chiefly metamorphosed quartz keratophyre and andesite and sparse dacite and basalt.  Metasedimentary rocks chiefly quartz-mica phyllonite, quartzi
U-Pb zircon yield ages of 375 Ma
hgs
Fine-grained schistose sedimentary rocks and volcanic rocks
Chiefly fine-grained, pale-yellow, pale-green, and graphitic black metasedimentary phyllonite and blastomylonite with minor metavolcanic blastomylonite.   Predominant lithologies are quartz-mica phyllonite, quartz-calc phyllonite, quartzite, marble, and
Dys
ag
Metamorphosed granitic rocks
Late to middle Cretaceous
Consists chiefly of metamorphosed stocks, dikes, and sills of diorite and minor quartz diorite, granite, granodiorite, and gabbro.  Fine- to medium-grained, having relict hypautomorphic granular texture.  Unit moderately deformed and exhibits moderate sc
U-Pb zircon age of 71 Ma.  In adjacent Healy quadrangle, Ar-Ar analysis of hornblende yielded 106 Ma.  K-Ar ages on biotite range from 18.2 to 27 Ma and hornblende 36.8 Ma
Kmi
as
Metamorphosed sedimentary rocks
Triassic to Silurian
Chiefly of fine- to medium-grained, mylonitic, calc-schist, marble, quartz-mica schist, and quartzite.  Protoliths thought to be marl, limestone, pelite, and sandstone.  Unit intensely ductily deformed and schistosity dips steeply to vertically and strik
Conodont fragments of post-Ordivician age
wm
Cretaceous, Devonian, and Silurian
Structural melage consisting of two assemblages:  1) Cretaceous flysch and volcanic rocks consisting mainly of argillite, and weakly metamorphosed quartz silitstone, quartz sandstone, graywacke, and conglomerate and minor andesite and acite and 2) Small
Cretaceous ammonite in unit 1 and Silurian(?) and Devonian mega- and micro-fossils.
Tsc
Chiefly continental clastic deposits of light-colored, fine-grained, poorly sorted sandstone and having locally interbedded siltstone, pebbly sandstone, pebble to cobble conglomerate, and sparse thin coal layers.  In vicinity of "The Hoodoos", contains v
Plants and pollen of late Eocene to Pliocene age
K-Ar ages of hornblende from included ash were 5.5  and 31.1 Ma
Conglomerate
Chiefly continental clastic deposits of poorly sorted, crudely bedded to massive, polymictic conglomerate and lesser sandstone. Contains clasts of rhyodacite to dacite tuff, the Nikolai Greenstone, argillite, volcanic sandstone, andesitic to dacitic rock
Tv
Chiefly vitric-lithic-crystal ash-flow tuff, breccia, agglomerate, flows, dikes, and sills, and minor volcanic sandstone, conglomerate, and fossiliferous limestone.
K-Ar whole-rock age on tuff was 49 Ma
grs1
Cretaceous and Late Jurassic
Chiefly granitic and minor monzonite and diorite dikes, stocks, and small plutons.  Fine- to medium-grained, hyautomorphic granular texture.  Locally metamorphosed to lower greenschist facies.
KJg
grs2
Chiefly hornblende-biotite granodiorite and hornblende granodiorite and minor granodiorite and granite dikes, stocks, and small plutons.  Includes sparse syenodiorite and quartz diorite.  Fine- to medium-grained, hyautomorphic granular texture.  Locally
grs3
Quartz diorite and diorite dikes, stocks, and small plutons.  Includes sparse syenodiorite and quartz diorite.  Fine- to medium-grained, hyautomorphic granular texture.  Locally metamorphosed to lower greenschist facies.
grsg
Granite of Susitna Glacier
Chiefly biotite-white mica granite.  Fine- to medium-grained, hyautomorphic granular texture.
Three K-Ar hornblende and biotite ages of 35.5 to 36.1 Ma
Toegr
grcl
Granite porphyry of Caribou Lake
Early Cretaceous and (or) Late Jurassic?
Chiefly biotite granite porphyry.  Fine-grained; locally medium-grained.  Local hyautomorphic granular texture.  Local extensive hydrothermal alteration.
grrm
Granodiorite of Rainbow Mountain
Early Cretaceous and (or) Mississippian
A possible Late Mississippian age from K-Ar hornblende analysis 326 Ma.
um
Ultramafic and associated rocks
Mesozoic?
Chiefly variably serpentinized pyroxenite, peridotite, dunite, schistose amphibolite, serpentinite, and hornblende-plagioclase gneiss derived from gabbro.  Locally intruded by gabbro dikes, tonalite, and granite.  Intensely deformed and fault-bounded.
K-Ar ages on hornblende and biotite of 123 and 126 Ma
Mzum
gg
Gneissose granitic rocks
Chiefly gneissose granodiorite and quartz diorite and minor granite.  Fine- to medium-grained, with relict hypautomorphic granular, seriate, and porphyritic textures.  Locally grades to migmatite.  Unit metamorphosed at middle to upper amphibolite facies
U-Pb zircon and sphene and K-Ar mica and hornblende ages range between 29.2 to 70 Ma.
TKgg
sa
Schist and amphibolite
Late Cretaceous or older
Chiefly garnet-biotite-plgioclase schist and hornblende amphibolite.  Relatively older, more mafic, and more highly metamorphosed variation of gneissose granitic rocks (unit gg) which locally intrude this unit.  Intensely regionally metamorphosed and pen
Mzsa
mig
Migmatite
Transitional rock unit between mimatitic schist (unit mgsh) and gneissos granitic rocks (unit gg).  Grades from gneissose granitic rocks, containing fragments of nearly completely assimilated schist and amphibolite, to highly contorted schist and amphibo
mgsh
Migmatitic schist
Grades from schist and amphibolite (unit sa) containing diffuse granitic dikes concordant to schistosity, to contorted and partly assimilated schist and amphibolite.
K-Ar ages range from 31.9 to 65.9 Ma, hornblende ranging from 58.5 to 65.9 Ma and biotite from 31.9 to 56.9 Ma.
sq
Schist, quartzite, and amphibolite
Triassic?
Unit of relatively older calc-silicate schist, quartzite, and amphibolite.  Moderately to intensely deformed with a moderate schistosity.  Fine- to medium-grained.  Evidence suggests calc-silicate schist and amphibolite developed from marl.
Lithologically similar rocks in Healy quadrangle to west contain Pennsylvanian to Triassic conodonts and fragments of late Triassic bivalves.
msh
Quartz-mica schist, calc-schist, and amphibolite
Late Jurassic or older
Chiefly quartz-mica schist, amphibolite, and calc-schist.  Protoliths chiefly pelite, sandstone, graywacke, and minor marl, andesite, and gabbro.  Intensely deformed, with a strong schistosity.  Metamorphosed to amphibolite facies.
K-Ar analyses of biotite and muscovite range from 30.6 to 48.0 Ma, Single hornblende yielded age of 69.6 Ma.
Mzpca
mph
Chiefly fine-grained white mica-quartz phyllite, and minor quartz-plagioclase-white mica phyllite, clinozoisite-chlorite-quartz phyllite, calcite-chlorite phyllite, and quartz-rich marble and metaandesite.  Protoliths chiefly siltstone, metavolcanic silt
ma
Argillite and metagraywacke
Chiefly argillite, metagraywacke, and metaandesite locally.  Protoliths of siltstone, calcareous mudstone, and volcanic graywacke.  Unit strongly schistose.  Metamorphosed to lower greenschist facies.
csv
Schistose metasedimentary and metavolcanic rocks.
Chiefly fine-grained quartz-white mica-schist, chlorite-calcite-quartz schist, marble, greenstone, and sparse metadacite.  Protoliths of quartz-siltstone, calcareous silty sandstone, limestone, fine-grained basalt, and fine-grained dacite.  Unit exhibits
Correlative rocks in southeast Healy quadrangle contain Heterastridium sp. of Late Triassic age.
Trnm
umm
Ultramafic and mafic igneous rocks occurring along Broxson Gulch thrust
Cretaceous to Triassic?
Chiefly dunite, olivine-clinopyroxene cumulates, serpentinite, metagabbro, and metadiabase.  Unit occurs in scattered fault bounded exposures.  Local, low-grade metamorphism.
K-Ar ages on hornblende in gabbro dikes of 91.9 and 97.7 Ma
JTrm
McCarthy Formation
Chiefly rhythmically, thin- to medium-bedded, calcareous argillite and impure limestone, mainly spiculitic, skeletal, or intraclastic lime packstone.  Estimated maximum thickness of a few hundred meters.
Monotis M. subcircularia(?) of Late Triassic age
JTrmc
ga
Gabbro, diabase, and metagabbro
Late Triassic?
Chiefly hornblende gabbro, clinopyroxene gabbro, and hornblende-clinopyroxene gabbro and sparse quartz gabbro and hornblende quartz diorite.  Dark-gray, fine- to medium-grained, and mainly relict hypautomorphic granular texture, but locally porphyritic,
Trgb
cu
Cumulate mafic and ultramafic rocks
Chiefly consists of 1) fault-bounded lenses of olivine-cumulate and olivine-pyroxene cumulate in Slana River subterrane, and 2) large sills of olivine cumulate, olivine-pyroxene cumulate, and pyroxene-plagioclase cumulate in Tangle subterrane.  Include F
Marine metasedimentary rocks
Principally deep-marine turbidite deposits consisting of graded beds of metamorphosed dark-gray to gray argillite, siltstone, and graywacke, pebbly graywacke, pebble to cobble conglomerate, and sparse andesite.  Graded beds well-developed locally; consis
Late Jurassic megafossils, locally abundant Buchia in Nabesna quadrangle.
KJfm
Trl
Chiefly dark- to light-gray micrite, dismicrite, or microsparite.  Conformably overlies Nikolai Greenstone (unit Trn).  Fine- to medium-grained, medium- to massive-bedded containing lenses and nodules of gray and black chert and irregular patchworks of d
Locally contains moderately abundant Late Triassic mega- and microfossils.
Chiefly massive dark-gray-green, dark-gray-brown, reddish-brown, and maroon-gray subaerial, amygdaloidal basalt flows, separated locally by thin beds of reddish-brown nonmarine volcaniclastic rocks.  Unit pervasively metamorphosed to lower greenschist fa
Eagle Creek Formation
Early Permian
Chiefly conformable sequence of alternating marine argillite and limestone.  Divided into either an upper argillite and lower limestone unit in south central part of Mount Hayes quadrangle or two limestone and two argillite units in the eastern part of t
Abundant mega- and microfossils, mainly brachiopods, corals, and foraminifers, indicated an Early Permian age
Pi
Shallow-level intrusive stocks, dikes, sills, and small plutons.
Early Permian?
Sparse to locally abundant andesite, and lesser dacite and rhyolite, stocks, sills, and dikes that intrude Slana Spur Formation and Tetelna Volcanics.  Granoblastic overprint metamorphic texture with local weak schistosity.  Metamorphosed to lower greens
Pmi
PaPs
Slana Spur Formation
Early Permian to Middle Pennsylvanian
Chiefly a thick sequence of marine calcareous and noncalcareous volcaniclastic rocks and lesser limestone, tuff, and volcanic breccia.  Disconformably overlies Tetelna Volcanics.  Correlative with volcaniclastic member of Station Creek Formation of Skola
Megafossils and microfossils, mainly brachiopods, corals, and foraminifers, range from Middle Pennsylvanian through Early Permian.
K-Ar age on hornblende from a weakly metamorphosed mafic nodule was 94.4 Ma, possible age of low-grade regional metamorphism of Wrangellia terrane.
PaPsu
Slana Spur Formation -- Calcareous volcaniclastic rocks member
Predominantly gray-green, clastic, locally fossiliferous limestone and marble, and gray-green coarse-grained calcareous volcanic sandstone.  Includes minor volcanic conglomerate, light-gray-green lailli tuff, and andesite.  Metamorphosed to lower greensc
PaPsl
Slana Spur Formation -- Volcaniclastic rocks member
Dark-gray, dark-green, and maroon volcanic and volcaniclastic rocks.  Chiefly volcanic flows interbedded with lapilli tuff, volcanic breccia, graywacke, argillite, and limestone to marble.  Local massive to bedded conglomerate, graywacke, and siltstone.
PPasc
Tetelna Volcanics
Pennsylvanian
Chiefly dark-green, dark-gray-green, and purplish-gray-green volcanic flows, mud and debris avalanches, locally graded, and lapilli-pumice tuff interbedded with fine- to coarse-grained volcaniclastic rocks.  Flows mainly andesite, unit metamorphosed to l
Pag
Granitic plutons south of Denali fault
Chiefly granite.  Generally medium-grained hypautomorphic granular texture, locally porphyritic.
U-Pb zircon age of 309 Ma, interpreted as intrusive age.  K-Ar  hornblende age of 326 Ma of granodiorite at Rainbow Mountain, older than wall rocks at locality.
PPagi
Fine- to medium-grained, medium- to massive-bedded limestone.  Generally calcite clasts in a very fine-grained matrix of calcite and quartz.  Moderately to highly recrystallized, locally weakly schistose.
Late Triassic cephalopods and pelecypods.
Trnf
Nikolai Greenstone -- Subaerial basalt flows member
Chiefly dark gray-green, gray, purple, black, or brown, massive amygdaloidal basalt flows.  Fine- to medium-grained.  Includes sparse basaltic breccia and basaltic aquagene tuff and sparse limestone, siltstone, shale, and chert occur in south-central par
Trnp
Nikolai Greenstone -- Pillow basalt flows member
Chiefly interlayered dark gray-green pillow basalt flows and minor basaltic flow breccia, aquagene and epiclastic tuff, breccia, argillite, and radiolarian chert.  Unit metamorphosed to lower greenschist facies.
Middle or Late Triassic Daonella or Halobia in one locality.
Pzt
Aquagene tuff, argillite, limestone, chert, andesite tuff, and greenstone
Late Paleozoic
Chiefly andesite flows, mud and debris avalanche deposits, and tuff interbedded with fine- to coarse grained volcaniclastic rocks.  Contains lesser interlayered basaltic aquagene tuff, gray-green andesite tuf, gray-green basalt, dark-gray siliceous argil
Fragements of Late Paleozoic bryozoans.  Correlative unit in Talkeetna Mountains D-2 quadrangle contains Early to Late Permian conodonts.
mha
Metamorphosed hornblende andesite
Late Paleozoic?
Porphyritic hornblende andesite metamorphosed mainly to  lower greenschist facies.  Metamorphic grade increases to lower amphibolite facies adjacent to metamorphosed granitic and gabbroic plutons; later retrogressed to lower greenschist facies.  Schistos
PPast
Q
Undifferentiated surficial deposits
The deposits include alluvium, colluvium, talus, landslides, rock glaciers, eolian and paludal deposits, and a variety of lacustrine, morainal, and ice contact.
VA002
Valdez
Tif
felsic to intermediate hypabyssal intrusive rocks
Dikes, sills, and small stocks, compositionally diverse, dacite predominates but rocks range from rhyodacite to quartz latite and andesite.
K-Ar age of 47 and 52 Ma reported as well as numerous 40 to 50 Ma ages and some as young as Pliocene.
QTw
Wrangell Lava
Quaternary and Tertiary?
At least 2,000 m of flows, tephra, and minor sedimentary rocks in northeastern Valdez quadrangle.  Consists of mainly pyroxene andesite but ranges from basalt to dacite.
Dates as old as 2.7 to 10 Ma in adjacent Nabesna quadrangle, thought to be largely Quaternary in Valdez quadrangle.
Kb
Berg Creek Formation
Marine clastic rocks consisting of calcareous conglomerate, conglomeratic sandstone and siltstone, and calcarenite.  Basal strata generally are pebble, cobble, and boulder conglomerate consisting of clasts derived from nearby bedrock.
Kbc
Js
Unnamed Jurassic marine sedimentary rocks
Middle Jurassic (Callovian)?
Marine clastic rocks consisting mostly of sandstone, siltstone, and mudstone, which contain many interbeds of pebble- and cobble-conglomerate.  Greenish-gray sandstone predominates in lower part of the sequence, in many places it is calcareous and cross-
Unnamed Callovian fossils
Juc
Jk
Kotsina Conglomerate
Middle or Late Jurassic?
Well-indurated massive to very thick-bedded cobble- and pebble-conglomerate, with some bouldery strata.  Olive-gray lithic and feldspathic sandstone, siltstone, and carbonaceous shale are interbedded in many places and increase in proportion west of Long
Plant scraps
K-Ar age on biotite from a clast of 161 Ma and on hornblende from cross-cutting dike of 145 Ma
Jkt
McCarthy Formation -- lower member
Early Jurassic? and Late Triassic (Norian)
Marine limestone, shale, and chert.  Lower member consists of interbedded finely-laminated, dark-gray, impure limestone, subordinate fissile shale, and minor chert.
Monotis and both calcareous and silicieous microfossils.
Minimum age from intruding granodiorite of 144 Ma
Chitistone and Nizina Limestones
Late Triassic (Karnian and Norian)
Light- to medium-gray limestone of diverse textural varieties and include minor dolomite lower in the sequence and nodules and lenses of dark-gray chert high in the sequence.  Lower thicker-bedded sequence is Chitistone Limestone, upper, thinner-bedded s
Middle and (or) Late Triassic
Weakly metamorphosed, lightly altered tholeiitic basalt that is characteristically amygdaloidal and poorly bedded.  Metamorphosed to prehnite-pumpellyite facies
K-Ar whole-rock isochron of 112 +/- 11 Ma thought to indicate collosion of Wrangellia with North America
Skolai Group -- greenstone unit
Late Paleozoic, Middle Pennsylvanian to Early Permian
Diverse Upper Paleozoic volcanic, volcaniclastic, and marine sedimentary rocks.  Unit consists largely of two lithologies, map unit Pzs is dark, greenish-gray poorly bedded greenstone, characterized by prehnite-pumpellyite mineral assemblages, locally re
Skolai Group -- marble unit
Subordinate light- or medium-gray and buff calcareous rocks, mostly recrystallized to marble but containing scanty fragments of fossils, interbedded with dark-gray calcareous siltstone and shale.  Change unit designator to ma, per Winkler (1998)
Scanty fragments of bryozoans, crinoids, corals, and brachiopods.
Pzskm
Psm
Strelna Metamorphic Complex
A diverse and intimately mixed group of low- to medium-grade greenschist and amphibolite which also includes abundant pelitic and psammitic schist, metachert, and gneiss having pronouced mortar structure.  Contains no marble but does contain extensive ma
K-Ar age on hornblende from metagabbro of 152 +/- 6 Ma; thought to be reset.
Tg
Granite and granodiorite
Tertiary? (Eocene?)
Two small discordant stocks of biotite-hornblende granite and granodiorite.  Unfoliated, fine- to medium-grained hypiomorphic granular rocks.  Equal proportions granite and granodiorite.
Jc
Chitina Valley batholith
Weakly to strongly foliated compositionally diverse plutonic rocks.  Dominant lithology is fine-to medium-grained hypiomorphic granular quartz monzodiorite, but quartz diorite, tonalite, and granodiorite are nearly as abundant.
K-Ar hornblende ages range from 147 +/- 7 to 157 +/- 8 Ma, biotite ages are 134 and 144 +/- 7 Ma; one mineral pair is slightly discordant.
Jqd
Pzg
Gabbro and leucogabbro
Late Paleozoic, Permian to Pennsylvanian
Gabbroic rocks rocks consisting of sills, dikes, and discordant plutons.  Medium- to coarse-grained, massive to foliated, altered gabbro, leucogabbro, and minor diorite.  Coextensive with layered gabbro in the McCarthy quadrangle.
K-Ar age on actinolitic amphibole of 246 +/- 12 Ma, thought to be minimum age, may be partially reset by intrusion of nearby Late Jurassic hornblende granodiorite pluton.
Pagb
Klc
Schist of Liberty Creek
mid-Cretaceous? or Jurassic??
Well-foliated, multiply-deformed greenschist and transitional blueschist facies mafic metavolcanic and metasedimentary rocks.  Schistocity is well-developed although primary sedimentary or volcaniclastic features are retained locally.  There are no marke
Jsch
Bernard Creek terrane, deleted, now McHugh Complex
mid-Cretaceous?
Mylonitic greenschist.  Relict bedding and volcaniclastic textures are retained locally.  Elsewhere unit is nearly massive, but cataclasis and neomineralization generally are so pervasive that they obliterate any primary features.
Kmk
Kfc
Fox Creek terrane  Unit deleted on new VA map
Intercalcated lower greenschist and transistional blueschist facies metasedimentary and mafic metavolcanic rocks.  Over broad areas the rocks have a cataclastic fabric, locally relict primary sedimentary and volcaniclastic textures are retained.  Unit is
Khc
Haley Creek terrane
Metamorphosed complexly deformed and tectonically mixed plutonic and sedimentary rocks.  Metaplutonic rocks are most abundant in southern part of the terrane and are compositionally diverse and weakly to strongly foliated.  Although diorite and granodior
Kag
Haley Creek terrane -- metaplutonic rocks
K-Ar ages on hornblende range from 122 to 148 Ma.  A muscovite age is 133 +/- 4 Ma
M
Haley Creek terrane -- schistose marble
Schistose marble.  Individual marble layers can be traced for several km, however the layers vary greatly in thickness, terminate abruptly in places, and are generally thoroughly folded.  Small isolated bodies of marble mark unmapped fault within the Hal
PPaskm
Hornblende andesite or dacite dikes
Porphyritic hornblende andesite or dacite dikes
Tva
Tt
Altered biotite and hornblende tonalite
Small, sericitized hornblende-biotite tonalite plugs.  Rocks are fine- to medium-grained sericitized tonalite with minor quartz diorite and granodiorite.  In most sample, muscovite replaces biotite or has formed from alteration of plagioclase.
K-Ar hornblende 46.6 +/- 1.4 and muscovite of 52.4 +/- 2.6 Ma
Jgl
Hornblende gabbro and leucogabbro
Early Jurassic or older
Layered gabbro and leucogabbro; layered gabbro is dominantly hornblende gabbro; hornblende-augite gabbro is common, however, with the hornblende replacing or molded upon the augite; and layers and lenses of hornblendite occur at several places.  Mafic pa
K-Ar ages on hornblende of 419+/- 21, 188 +/- 8, and 171 +/- 5 Ma; the older age is considered suspect.
Dunite, harzburgitic dunite, wehrlite, websterite, and clinopyroxenite comprise the Tonsina ultramafic complex.  The rocks are folded but not intensely sheared or serpentinized.
Kmu
Matanuska Formation -- upper part
Late Cretaceous -- mid-Coniacian to Maestrichtian
A very thick sequence of marine siltstone, claystone, and sandstone in interbedded with lenticular and channelized deposits of sandstone and conglomerate.  Contact with lower part of unit presumed to an unconformity.  Deposition thought to occur on the f
Kml
Matanuska Formation -- lower part
Late Cretaceous -- late-early-Albian, Cenomanian, Turonian, and early Coniacian
Marine siltstone, shale, sandstone, and pebbly sandstone are interbedded with subordinate silicieous, foraminiferal shale and fine-grained zeolitized sandstone.  Contact with upper part of unit (unit Kmu) presumed to be an unconformity and is angular unc
Jtk
Talkeetna Formation
Early Jurassic
Marine and non-marine andesitic and basaltic tuff, tuff breccia, and volcanogenic sedimentary rocks.  Small, isolated bodies of light- to dark-gray unfossiliferous saccharoidal limestone may be parts of the units in the Valdez quadrangle.
Mollusks and brachiopods
JTrtk
Jgr
Biotite-epidote granite
Middle Jurassic
Irregularily shaped small stocks of pink-weathering medium-grained granite.  Green biotite and granular to coarse-grained epidote are constant accessories
Jgd
Biotite-hornblende granodiorite
Irregularily shaped small stocks of pink-weathering medium-grained granite.  Green biotite is a constant accessory; hornblende and epidote are less abundant and are not present in all samples.
Jmp
Mafic plutonic complex
Early or Middle Jurassic
Consists dominantly of layered hornblended-pyroxene gabbro and leucogabbro, with minor ultramafic, dioritic, and tonalitic rocks.  The southern margin of complex is a major fault zone; cataclastic modification of mineral layering in the complex near the
K-Ar ages on low-potassium hornblende and chloritized biotite range from 153 to 171 Ma.
Jan
Jurassic?
Serpentized pyroxenite?  Occurs within mafic plutonic complex (unit Jmp), generally localized in strongly sheared zones.  Many areas of unit are too small to map.
Tov
Orca Group -- volcanic rocks, undivided
Paleocene and Eocene?
Tholeiitic pillow basalt, pillow breccia, and minor aquagene tuff.  Thin sequences of  dray-gray argillite and siltstone are interbedded with the volcanic rocks and locally compressed between pillows.  Volcanic rocks are exclusively of oceanic tholeiite
Tos
Orca Group -- sedimentary rocks, undivided
Marine argillite, siltstone, sandstone, and conglomerate.  Argillite and siltstone are more abundant the coarser-grained rocks.  Well-bedded, repetitive finer-grained and coarser-grained strata; primary sedimentary features are diagnostic of deposition b
Toc
Orca Group -- conglomeratic sedimentary rocks
Very poorly bedded conglomeratic sandstone and argillite mantle the tops of volcanic sequences.  Conglomeratic rocks are very poorly sorted; clasts vary in size from granules to boulders and are supported by matrix.  Basal parts of conglomeratic frequent
Orca Group -- melange
Tertiary or Cretaceous
Consists of extensive serpentinized ultramafic rocks including dike-like bodies of rodingite, as well as blocks of layered gabbro, crossite schist, pillow basalt, marble, chert of probable Late Triassic or Early Jurassic age, and diverse metamorphosed an
TKmx
Kvv
Valdez Group -- Metavolcanic rocks, undivided
Mafic metatuff and minor massive or weakly foliated greenstone having rarely preserved vague pillow shapes.  Lower greenschist facies metamorphism.  Most of these metavolcanic rocks are schistose and the metavolcanic are often the loci of intense deforma
K-Ar whole-rock age on metatuff of 53.5 +/- 1.6 Ma is thought to date matamorphism.
Valdez Group -- Metasedimentary rocks, undivided
Weakly to strongly foliated marine argillite, siltstone, sandstone, and conglomeratic sandstone.  Lower greenschist facies metamorphism.  Probable volcanic source terrane.
Maestrichtian pelecypods collected outside of Valdez quadrangle.
Valdez Group -- Phyllite and schist. Delete unit on new VA map
Low-grade metamorphosed (lower greenschist facies) pelitic rocks consisting of homogeneous phyllite and schist.  These rocks shown much stronger foliation than the undivided metasedimentary rocks (unit Kvs) of the Valdez Group.  Probable volcanic source
KJm
McHugh Complex
Early Cretaceous and Jurassic?
Pervasively deformed assemblage of diverse lithologies (melange).  Lithologies include gabbro, greenstone, marble, wacke, and diverse plutonic and metamorphic rocks including blueschist.  Rocks occur in three discrete belts, the northernmost which yields
Radiolaria from chert ranges from Triassic to mid-Cretaceous (Albian or Cenomanian).
Greenschist and transitional blueschist
Jurassic
Chiefly intercalated greenschist and blueschist, but includes lawsonite, muscovite, or actinolite schist, carbonaceous schist, highly siliceous rocks containing stilpnomelane, and foliated calcareous rocks.  Similar to Raspberry, Seldovia, and Knik River
K-Ar ages on crossite and muscovite range from 152 to 175 Ma, thought to be metamorphic ages.
Ja
Amphibolite facies rocks
Jurassic(?)
Portion of tectonic inclusion 10 by 15 km in McHugh Complex consisting of layered quartz gabbro, amphibolite, and orthogneiss.  This unit consists of nondescript, amphibolite facies, weakly foliated to nonfoliated granular rocks of uncertain protolith.
Jag
Uranatina River metaplutonic unit
Jurassic and Middle Pennsylvanian
Portion of tectonic inclusion 10 by 15 km in McHugh Complex consisting of layered quartz gabbro, amphibolite, and orthogneiss.  This unit consists of compositionally banded very mafic amphibolite to hornblende-biotie dioritic and quartz dioritic gneiss.
Low-potassium hornblende yielded K-Ar age of 267 +/- 8 Ma (mid-Permian), thought to approximate time of metamorphism.
JPaur
Jlg
Layered quartz gabbro
Conspicously layered, hypiodiomorphic-granular textured quartz gabbro.  Layers enriched in clinopyroxene or in plagioclase and quartz give unit its prominent banded appearance.  Prehnite-pumpellyite metamorphosed, little deformed and dips quite uniformly
K-Ar age on pyroxene of 185 +/- 19 Ma is highly suspect, however matches ages on Afognak Pluton, the pluton of the Barren Islands and reputed ages on small dioritic plutons near Seldovia.
Qp
Placer mine tailings
Holocene (Historic)
Symmetrical to irregular piles of artificially water-worked, sorted gravel and in situ slab rock derived from bedrock.
ID002
Iditarod
Qpm
QTs
Holocene to Pliocene(?)
Unconsolidated fluvial, terrace, colluvial, glacial, and eolian deposits, usually covered by vegetation.  Deposits range between 3 and 20 m thick and generally contain permafrost to some degree.  Unit primarily Pleistocene to Holocene in age, however str
Tb
Basaltic andesite
Tertiary -- Miocene
Very fine grained to aphanitic, dark- to medium-gray, locally vesicular, augite basaltic andesite.
K-Ar whole-rock age of 6.9 and 13.0 Ma
Tba
TKy
Volcanic rocks of Yetna River area
Tertiary and Late Cretaceous
Chiefly subaerial lava flows of andesite, dacite, rhyolite, and minor basalt and subordinate welded to nonwelded rhyolitic to andesitic ash-flow tuff.
Eight of nine samples yielded K-Ar ages between 54.4 and 68.7 Ma, ninth sample yielded age of 25.5 Ma on tuff.
TKil
Iditarod Volcanics -- Andesitic to basaltic subaerial lava flows and mafic volcanic breccia
Subaerial, locally columnar-jointed, aphanitic to porphyritic, olivine-clinopyroxene basaltic andesite, clinopyroxene andesite, and minor dacite; volcanic breccia locally interfingers with flow rocks.
K-Ar ages from 4 samples ranged between 58 and 66 Ma; one whole-rock yielded a 35.1 Ma minimum age.
Kit
Iditarod Volcanics -- Tuff, volcanic breccia, altered andesitic to dacitic flows and volcaniclastic sandstone
Heterogeneous assemblage characterized by lithic, crystal, and water-laid tuff and altered intermediate lava flows.; locally includes volcanic breccia, volcaniclastic sandstone, and lahar deposits.  Lithologically identical to unit Kkt; distinguished by
K-Ar ages from 5 samples ranged between 70.3 to 76.7 Ma; two youngest are considered minimum ages.
Kkq
Kuskokwim Group -- quartzose sandstone and siltstone
Late Cretaceous, (Paleocene?) Campanian to Turonian?
Quartzose sublithic sandstone, conglomerate, siltstone, and siliceous shale.  Finer-grained layers locally contain abundant coaly leaf and stem debris; thin coal seams are present locally.  Coquina layers composed of brackish to fresh water bivalves are
Dicotyedon leaf fragment of probable Turonian to Paleocene age but may be as old as Cenomanian.
K-Ar age of 77 Ma on interbedded andesite tuff in upper part of section.
Kks
Kuskokwim Group -- sandstone, siltstone, shale, and conglomerate
Late Cretaceous, Campanian? to Cenomanian?
Thick assemblage of fine- to coarse-grained lithic sandstone, micaceous siltstone, shale, and minor chert-pebble conglomerate; major part of Kuskokwim Group in quadrangle.  Sandstone is lithic rich; nearly all contain metamorphic lithic fragments, but pl
Pelecypods of Turonian or probable Turonian age but may be as old as Cenomanian based on fossils outside of Iditarod quadrangle.
Kkt
Kuskokwim Group -- volcanic tuff and agglomerate
Hetergeneous assemblage of tuff, agglomerate, cherty tuff and locally, minor sandstone.  Lithologically identical to unit Kit, units only distinguished by surrounding rocks.
K-Ar ages of 69.4 and 71.3 Ma on whole rocks, questionable due to alteration.
Kka
Kuskokwim Group -- altered andesite flows, tuffs, and sills?
Late Cretaceous; Campanian
Layers of intermediate igneous rocks 1 to 5-m-thick interbedded with unit Kks.  Consists of andesitic flows and tuffs, and possible sills.
K-Ar age of 77 Ma
Kkv
Kuskokwim Group -- volcanic flow(s) and tuff
Hornblende-clinopyroxene andesitic volcanic flow(s) and chlorite-calcite altered tuff.  Interbedded with unit Kks.
Sandstone and siltstone
Medium-grained to very fine grained sandstone, tuffaceous sandstone, and siltstone only exposed as colluvial chips in western part of Iditarod quadrangle.
Age based on Hauterivian to Barremian palynomorphs in one sample.
Chert, volcanic rocks, metasandstone, and limestone
Triassic to Mississippian
Radiolarian chert, clinopyroxene basalt to basaltic andesite, lithic tuff, water-laid tuff, metasiltstone, and minor fossiliferous shallow-water limestone.  Occurs as fault slivers? in northeastern part of Iditarod quadrangle or associated with the Dishn
Late Triassic (or possibly Jurassic) radiolarians and conodonts and crinoidal hash no older than mid-Mississippian.
K-Ar hornblende age of 302 +/- 9 Ma on porphyritic volcanic rock; 3 K-Ar whole-rock ages on greenstones (88.4 +/- 2.7, 110 +/- 3, 76.5 +/- 2.3 Ma)
Tp
Porphyritic granodiorite plug
Granodiorite consisting of abundant phenocrysts of hornblende and plagioclase in a finer-grained, phaneritic groundmass.
K-Ar age on amphibole of 52.8 Ma
TKgp
Hypabyssal granite porphyry dikes, sills, and plugs
Porphyritic to fine-grained phaneritic dikes, sills, and plugs of granitic composition.
22 K-Ar ages in two groups; 71.5 to 69.1 Ma and 65.7 to 63.5 Ma.  Most reliable ages all in older group (FHW).
TKp
Pilotaxitic dacite-andesite plugs
Three small bodies of subvolcanic dacite to andesite.  Pilotaxitic texture to the fine-grained groundmass.  Sparse phenocrysts of granophyric plagioclase and rare pyroxene.
Monzonite, quartz monzonite, syenite, granodiorite, granite, and minor lamprophyre
Small stocks and plutons of fine- to coarse-grained, phaneritic to hypidiomorphic, clinopyroxene-biotite +/- olivine monzonite, hornblende-clinopyroxene-biotite quartz monzonite, biotite syenite, biotite-hornblende granodiorite, biotite granite, and rare
20 K-Ar ages have bimodal distribution, 73.2 to 68.3 Ma and 63.4 to 59.4 Ma.  Many of the younger ages are suspect due to very low K2O in the biotites (FHW).
Altered intermediate to mafic dikes
Porphyritic biotite-clinopyroxene-plagioclase +/- olivine dikes, which are partly to extensively altered to chlorite-calcite-silica assemblages.
K-Ar age on biotite of 71.2 Ma
Alkali granite
Tertiary and Cretaceous
Poorly exposed, medium-grained, granophyric alkali granite  Light colored unit (CI < 7) containing varying mafic mineral assemblages, alkali amphibole-pyroxene-biotite to chloritized biotite
K-Ar age on biotite of 140 Ma, suspect due to extremely low K2O, amphibole age from adjacent Holy Cross quadrangle of 62.9 Ma
Jdr
Dishna River mafic and ultramafic rocks
Poorly exposed mafic and ultramafic that include two-pyroxene gabbronorite, clinopyroxene-hornblende gabbro, hornblende gabbro, diabase, harzburgite, minor dunite, and rare pyroxenite.  Original igneous textures well preserved in most samples, however se
Dubious K-Ar ages on hornblende (replicated) of 222 +/- 23 and 228 +/- 25 Ma and 92.2 +/- 2.8 Ma
PzPlg
Greenschist, pelitic schist, and metagranite
Paleozoic and Proterzoic?
Generally poorly exposed, mixed assemblage of greenschist facies metamorphic rocks including mafic meta-igneous rocks, subordinate metasedimentary rocks (pelitic schist, phyllite, calcareous schist, and quartzite) and minor granitic orthogneiss.
K-Ar biotite age from granitic orthogneiss was 108 Ma, thought to be post-metamorphic cooling age.
PzZrmc
Xi
Idono Complex
Early Proterozoic
Foliated meta-plutonic rocks, lesser amphibolite, and minor metasedimentary rocks.  Compositionally diverse metaplutonic rocks are primarily biotite +/- muscovite granitic orthogneiss but include orthogneiss of tonalitic, granodioritic, quartz dioritic,
U-Pb zircon age of 2.06 Ga; K-Ar ages range from approximately 120 Ma to approximately 1,230 Ma.
g
Glaciers and superglacial moraine
Exposed glacial ice locally mantled by unsorted jumbles of fresh boulders, cobbles, sand, silt, and mud as much as several meters thick.
AN002
Anchorage
Widespread glacial, alluvial, colluvial, and lacustrine deposits, rock glaciers, and landslides; have not been subdivided. Glacial deposits include extensive ground, lateral and terminal moraines, and associated outwash deposited during several advances
Ttk
Tyonek Formation
Carbonaceous sandstone, siltstone, shale, and claystone in several isolated outcrops near the town of Eagle River and along the Little Susitna River south of the Castle Mountain fault .  Maybe correlative with Tyonek Formation of upper Cook Inlet.  Outcr
early Seldovian Stage plants remains
Volcanic Rocks
Miocene to Paleocene
Upper part of sequence consists of andesite and basalt flows and minor rhyolitic tuff, lithofeldspathic sandstone, and fluviatile conglomerate.  Lower part consists of stocks, dikes, lenticular flows, and pyroclastic rocks, chiefly of quartz latite, and
Near Nelchina volcaniclastics contain Eocene plant fossils
Whole-rock K-Ar age 60 ma near middle of sequence; whole-rock ages of 54 to 56 ma from volcanic rocks in the Arkose Ridge Formation
Tsadaka Formation
Oligocene
Poorly sorted cobble to boulder conglomerate, consisting of plutonic clasts, interbedded with lenses of feldspathic sandstone, siltstone, and shale.  Local provenance, rapid lateral lithology and thickness changes;  correlative with the Hemlock Conglomer
Tw
Wishbone Formation
Fluvialtile conglomerate and thick interbeds of sandstone, siltstone, and claystone, with local partings of volcanic ash. Extends at least 30 km northward intoTalkeetna quadrangle.  South of Castle Mountain and Caribou faults, contact with Chickaloon For
Chickaloon Formation
Eocene and Paleocene
Fluvialtile and alluvial carbonaceous mudstone, siltstone, conglomeratic sandstone, and polymictic conglomerate.  Middle and upper portions of unit contain numerous beds of bituminous coal; lower part consists of conglomerate and lithic sandstone.  A loc
Lower part extn\ends into Paleocene based on plant leaves which correlate to flora present in the Fort Union Formation.  Also palonology studies by oil  industry.
K-Ar and fission-track ages ranging from 56 to 53 Ma on ash partings from coal beds in the upper Chickaloon NW of Jonesville
Tch
Tar
Arkose Ridge Fomation
Fluviatile and alluvial feldspathic and biotite-bearing sandstone, conglomerate, siltstone, and shale and thin beds of lignitic coal.  West of Chickaloon River, lower part of formation contains intercalated basalt flows and rhyolite tuffs which may corre
abundant plant fragments some of late Paleocene age
metamorphic biotite age of 67.5  +/- 2.4; K-Ar whole rock dates range from 56 to46 Ma for lower part of fm.;K-Ar whole rock date of 46 Ma for a basalt dike from the middle of the fm.
Matanuska Formation
Late and Early Cretaceous (Albian to Maestrichtian)
Fossiliferous marine shale containing conspicuous calcerous concretions and volcanic-lithic siltstone, sandstone, and subordinate conglomerate ;diverse shallow -to-deep marine (turbiditic) deposits.  Upper part, at least, is coeval with the Valdez Group
Jn
Naknek Formation
Late Jurassic (Oxfordian to late Kimeridgian)
Thin- to thck-bedded, fossiliferous marine siltstone, shale, and litho-feldspathic sandstone and conglomerate.   Principally composed of pluton and volcanic detritus.  Lower contact disconformable to slight angular unconformity and upper contact is uncon
Chinitna Formation
Middle Jurassic (late Bathonian (?) and early and middle Callovian)
Shallow- marine shale, siltstone, and subordinate sandstone  containing numerous large limestone concretions; incorporates volcanic and plutonic detritus from the Talkeetna arc.  Disconformably overlies Tuxedni Group.  Thickness varies locally but is as
type not described but age late early Callovian
Jt
Tuxedni Group
Middle Jurassic (Bajocian and Bathonian Stages)
Fossiliferous shallow-marine siltstone, shale, and sandstone; upper part consists of thin- to thick-bedded, dark siltstone and shale; lower part consists of thin- to thick-bedded sandstone which is pebbly in places.  Lower contact is an angular unconform
Three new collections range in age form early and middle Bajocian.
Jtx
Large, discordant, epizonal pluton and two satellitic stocks of hornblende-biotite granodiorite and lesser tonalite and quartz diorite.  Plutons intrude the Talkeetna Fm. (JTrt) and quartz diortite (Jqd) and are overlain nonconformably by the Arkose Ridg
K-Ar  ages in the Talkeetna Mountains range from 173 to 168 Ma and include a concordant mineral pair.  In Chugach Mountains, a date of 175 to 174 Ma by a concordant K-Ar mineral pair was obtained.
Quartz diorite
Large, disconcordant, epizonal pluton ; medium to coarse-grained hornblende (+/- biotite) quartz diorite, but also includes diorite and tonalite.  Large areas have been sheared and altered.  Intrudes JTrt and Jma and is intruded by Jgd and is overlain no
Discordant K-Ar dates of 169 to 154 Ma (minimum ages)
Jqt
Quartz diorite and tonalite
Series of discordant intermediate plutons.  They are relatively homogeneous, fine- to medium-grained quartz diorite and tonalite.  Large areas are sheared and altered.  Plutons intrude JTrt and Jg and are intruded by Jgd
K-Ar ages range from 181 to 167 Ma and include a concordant mineral pair; zircon fission-track ages are 186 and 170 Ma
Jmip
Mafic and intermediate plutonic rocks
Middle to Early Jurassic
Complexly intermixed series of mafic to intermediate plutonic rocks.  Plutons consist of gabbronorite, hornblende gabbro, diorite, and tonalite.  Xenoliths of gabbro show ductile deformation as though they still were warm when intruded by silicic magmas.
K-Ar on hornblende and biotite are 194 to 165 Ma.  Twelve other K-Ar dates on hornblende and biotite range from 187 to 160 Ma.  U-Pb zircon ages range form 183 to 171 Ma.
Jg
Gabbronorite
Fine- to coarse-grained gabbroic rocks consisting primarily of gabbronorite, leucogabbronorite, and pyroxene-hornblende gabbro, lesser hornblende gabbro, and minor anorthisitic gabbro.  Primary magnetite and illmenite are abundant (as much as 15 percent)
K-Ar dates of about 177 Ma compare well with K-Ar  and Ar/Ar dates from Valdez quad rocks (ranging from 181-175 Ma).
Jgs
Sheared gabbronorite
Intensely sheared and altered serpentinized gabbroic and ultramafic rocks.  Serpentinized rocks occurr in most outcrops of gabbronorite (Jg) but have been mapped separately between the Nelchina and Matanuska Glaciers.
Ultramafic and mafic rocks
Cumulate ultramafics and mafics forming two large fault-bounded sequences in the northern Chugach Mountains; the Eklutna and Wolverine complexes.  The Eklutna is 2-3 km thick and 11 km long.   From base to top consists of chromite-bearing dunite, wehrlit
Both sequeces are undated but are intruded by dikes and plutons of Jmip.
Jma
Amphibolite and quartz diorite
Intricately intermixed amphibolite, foliated quartz diorite, and lesser trondhjemite.  Some minor biotite-quartz-feldspar gneiss.
Correlated to rocks of the Talkeetna Moutains quad that have a K-Ar date of 176 Ma
Jps
Quartz-muscovite-albite-chlorite (+/- garnet-biotite) pelitic schist.  Uniform in lithology and has no correlative rocks nearby.  Minerology indicates retrograded greenschist metamorphism.  Age of prograde metamorphism is inferred to be Jurassic.
K-Ar on muscovite from schist ranges from 66 - 51 Ma are presumed to be reset by intrusion of  TKt and TKg
Early Jurassic to Late Triassic
Andesitic, dacitic, and basaltic flows, flow breccia, tuff, shallow sills, and agglomerate.  In many places contains subordinate interbedded volcaniclastic sandstone, conglomerate, and fossiliferous marine siltstone and shale.  Limestone and marble bodie
JPzm
Metamorphic rocks undivided
Metasedimentary and metavolcanic rocks.  Strongly to weakly foliated and variably  metamorphosed from greenschist to amphibolote facies.  Intruded by Jmip and Jg rocks.  Sedimentary protoliths include shale, chert, tuffaceous arenite, and limestone.  Vol
Fusulinids dated as Permian
Minimum age of metamorphism of 177 Ma by K-Ar on actinolite.   This age may have been reset by a nearby 165 Ma pluton.  Hornblende K-Ar ages of 121 and 107 Ma and a hornblende Ar/Ar plateau age of 117 Ma on mafic schist indicate resetting during metamorp
Tmg
Granitic phase Miners Bay Pluton
Altered, medium-grained leucrocratic biotite granite pluton and associated dikes.  Granitic rocks include a slightly older mafic phase (Tmm), include both the Valdez and Orca Groups, and are cut by Contact fault
K-Ar age of  32.2+/- 1.6 Ma on biotite
Togr
Tmm
Mafic phase Miners Bay Pluton
Texturally and compositionaly varibale composite mafic pluton east of Unakwik Inlet. Pluton consists of medium-grained clinopyroxene +/- orthopyroxene gabbro and lesser  clinopyroxene-bearing diorite.  Quartz gabbro and quartz diorite occur near pluton m
K-Ar age of  38.4+/- 1.9 Ma on hornblende
Tgg
Oligocene or Eocene
Small plutons west of Columbia Glacier and south of Wells Bay that are coextensive with the Cedar Bay Granite and numeraous leucocratic dikes that intrude the Orca Group.  Plutons consist of  biotite+/- hornblende rganite and granodioriteic border phases
Tfp
Felsic Intrusions
Leucocratic dikes, sills, and small stocks occurring widely south of Border Ranges fault.  Only a few meters thick but laterally extensive; Dacite predominates, but rholite also is present.  Intrusions usually are pophyritic with fine-to medium-grained p
Two groups apparent using K-Ar and fission track: older group 55-48 Ma  and younger group 44-43 Ma.  Near Anchorage, a K-Ar age of  34 from a hornblende dacite dike
Td
Tim
Hypayssal mafic Intrusions
Small stocks and irregular-shaped dikes and sills of diorite porphyry, diabase, basalt, and lamprophyre widely exposed in the Matanuska Valley
Primative initial Sr/Sr and whole-rock K-Ar age of 41 Ma
Ti
Hypayssal felsic and intermediate intrusions
Small stocks and irregular-shaped dikes and sills of rhyolite, quartz latite, latite, and dacite widely exposed in Talkeetna Mountains and the Matanuska Valley. May correlate with felsic volcanic rocks in upper part of unit Tv.
Primative initial Sr/Sr indicate little crustal contamination during intrusion and 4 whole-rock K-Ar age of 46 to 38 Ma for stocks and 3 zircon fission tack ages of 41-37 Ma on felsic intrusions.
Calaclasite
Eocene? and Early Cretaceous?
Chlorite-rich, fine-grained granular rocks formed by cataclasis and retrograde alteration of mafic and ultramafic plutonic rocks and mafic volcanic rocks;  May be equivalent lithologically to sheared gabbronorite (Jgs).  Lithologies and fabrics of these
Deformation in the Border Ranges fault is at least as old as Early Cretaceous; however, much of the fabric may be an Eocene overprint from reactivation of the old thrust as a strike-slip  boundary.
TJds
Mafic and intermediate dikes, sills, stocks
Eocene? to Jurassic?
Numerous compositionally variable, altered dikes, sills, and small stocks intruding the Talkeetna Formation and Jurassic plutonic rocks in the Chugach Mountains.  Rocks types consist of fine-grained basalt, prophyritic andesite, and dacite
Whole-rock K-Ar ages of 130 and 38 Ma for two basalt dikes
early Paleocene and Late Cretaceous
Large, epizonal, biotite-muscovite pluton.  Pluton is principally granite, but also granodiorite and lesser quartz monzonite.
K-Ar ages on muscovite and biotite 67 and 65 Ma, respectively.
TKt
Tonalite
Large pluton of predominately biotite-hornblende tonalite and lesser biotite-hornblende quartz diorite.  Pluton is epizonal or mesozonal.  Weakly developed foliation occurs in many places, and orbicular textures are present locally.
K-Ar ages 73-67 Ma (possibly reset).
Kw
Willow Creek pluton
Pervasively altered, zoned pluton; based on its distincive aeomagnetic signature it is interpreted to extend at least to northern boundary of map area.  Pluton has a 30- to 200-m wide outer margin of hornblende quartz diorite and lesser hornblende tonali
Subconcordant K-Ar ages 79-72 Ma.  K-Ar ages from propylitized pluton and gold-bearing veins and dikes that cut the pluton indicate episodes of alteration and quartz veining at 66 and 57 Ma.
Kum
Serpentinized ultramafic rocks
Small, structurally bounded, pervasively sheared, discordant bodies of serpentinized ultramafic rocks wholly enclosed in pelitic schist (Jps) near Bald Mountain Ridge.
Age of origin unknown, but early Late Cretaceous K-Ar minimum ages 91-89 Ma are presumed to date their emplacement.
Sedimentary rocks of the Orca Group
Monotonous sequences of thin- to thick-bedded sandstone, siltstone, and mudstone.  Primary sedimentary features indicate deposition by turbidity currents
Conglomerate of the Orca Group
Massive, clast-supported pebble, cobble and boulder conglomerate to matrix-supported pebbly mudstone and sandstone; clasts generally are well rounded and consist entirely of sandstone and siltstone.  About 900 m thick near Miners Bay.
Tovs
Sedimentary and volcanic rocks of the Orca Group
Basaltic flows, pillow breccia, and tuff interbedded with fyschoid siltstone and sadstone southeast of Miners Bay.  Volcanic interbeds weather a conspicuous rusty color.
Metasedimentary rocks of the Valdez Group
Thick sequences of drab, rythmically alternating multiply deformed turbidites, including metasandstone, metasiltstone, argillite, slate, and phyllite, and rare beds of pebbly argillite and metasandstone;  generally beds are a few centimeters to a few met
Kvt
Mafic metatuff of the Valdez Group
Altered chlorite-epidote-actinolite semischist interbedded with metasedimentary rocks in a small area near the divide between Coal Creek and Metal Creek.  Believed to represent aquagene tuff analogous to widespread thicker metavolcanic rocks in Cordova a
Mzm
McHugh Complex of the Valdez Group
Mesozoic
Strongly deformed, melange-like assemblage of diverse lithologies between Eagle River and Border Ranges faults.  Broad zones as wide as 1 km of intense shearing lack any stratal continuity and, in many places, are marked by angular, elongate phacoids, ei
Kt
Leucotonalite and trondhjemite
Medium-grained plugs and elongate irregular-shaped, sill-like bodies of leucocratic plutonic rocks in northern Chugach Mountains in a zone about 5 km wide near Border Ranges fault.  Rocks are foliated and contain less than 10% mafic minerals including mu
K-Ar on hornblende 126-124 Ma, biotite 116 MA, and muscovite 110 Ma, and a concordant U-Pb age of 103Ma.  Ar/Ar ages on hornblende 129,125, and 114 Ma, biotite 123 Ma, and muscovite 118 Ma, and two Rb/Sr isochrons 133 and 130 Ma.
Ktt
Jtr
Trondhjemite
Two discordant, NE-trending, elongate, epizonal, muscovite-biotite, leucocratic plutons intruding Jurassic quartz diorite (Jqd) and amphibolite (Jma) in Talkeetna Mountains.  Bodies are generally altered and sheared and have a faint foliation locally.
K-Ar age from the northern pluton is 129 Ma and 2 K-Ar ages for hte southern pluton range from 134-142 Ma.  Four K-Ar ages from the northern pluton which extends in to the TK quad are tightly clustered from 143 to 149 Ma.
Limestone and marble
Unfossiliferous, massive to poorly bedded limestone near head of east fork of Kings River, and limestone lenses as much as 30 m thick in broad shear zones in the Talkeetna Formation along the Castle Mountain fault;  medium- to coarse-grained marble occur
Glacial and alluvial deposits, chiefly unconcolidated gravel, sand, and clay
TK002
Talkeetna Mountains
Paleocene to Miocene
Over 1500 m of felsic to mafic subaerial volcanics and related shallow intrusives.  Small stocks, irregular dikes, lenticular flows, and thick layers of pyroclastic rocks; predominately consists of fine- to medium-grained, generally medium-gray quartz la
K-Ar (3 samples) from andesite in the middle of the sequence
Hyabyssal Mafic Intrusives
Small stocks and irregular dikes of diorite prophyry, diabase, and basalt.  Probably the subvolcanic equivalent of the andesite flows of unit Tv.
Hyabyssal Felsic Intrusives
Small stocks and irregular dikes of rhyolite, quartz latite, and latite.   Probably correlative with the felsic subvolcanic equivalent of unit Tv.
Ttw
Tsadaka and Wishbone Fm Undivided
Miocene and (Paleocene to Eocene) respectively
The Tsadaka consists of cobble-boulder conglomerate with thin interbeds of sandstone, siltstone, and shale; about 200m thick.  The Wishbone Formation unconformably underlies the Tsadaka.  It comprises well-indurated fluvitile conglomerate with thick inte
Chickaloon Fm
Well-indurated, continental, dominately fluvatile sequence of massive feldspathic sandstone, siltstone, claystone, and conglomerate, containing numerous beds of bituminous coal; over 1500 m thick
Sedimentary, undifferentiated
Fluvatile conglomerate, sandstone, and claystone with a few interbeds of lignitic coal. Looks similar to the sedimentary rocks of the southern Talkeetna Mountains but lacks fossil evidence for definitive correlation.  The sequence is over 160 m thick.  I
Tgd
Contains hornblende and biotite.  Part of a small pluton along the northern edge of map area.
K-Ar on biotite 48.8 +/- 1.5 m.y. and on hornblende 44.8 +/- 1.3 m.y.
Biotite-Hornblende Granodiorite
Paleocene and Eocene
Granodiorite  predominates, but locally it grades into adamellite, tonalite, and quartz diorite.  All of these rocks are medium to dark gray, medium grained, generally structurless, and have granitic to seriate textures.  In all of them hornblende is the
K-Ar age on biotite 58.6 and 54.8
Tbgd
Biotite Granodiorite
Biotite granodiorite and adamellite in about equal proportions.  These rocks are light to medium gray, medium- to coarse- grained, and have granitic to seriate textures.  Biotite is the chief mafic mineral.   Faint flow structures evident.  Plutons are s
Considered to be the same age as Thgd.  K-Ar ages on biotite range from 56.3 to 58.6.
Tsmg
Schist, migmitite, and granite
Undifferentiated terrane of andalusite and sillimanite-bearing schist, lit-par-lit type migmatite, and small granitic bodies with moderately to well-developed foliation.  Contacts generally gradational between these rocks as it is between the schist and
K-Ar age on biotite of 58.7 m.y.
Tkt
Late Cretaceous and early Paleocene
Dominately biotite-hornblende tonalite, locally grades into quartz diorite.  The tonalite is medium gray, coarse to medium grained, has a granitic texture and a fairly well-developed primary foliation.
K-Ar age ranges on biotite of  61.7 to 72m.y.  K-Ar ages on hornblende 61 to 74.4 m.y.
TKa
Adamellite
Occurs in large epizonal plutons dominately adamellite but locally includes granodiorite.  Biotite is the chief mafic mineral.  Medium to coarse grained, medium to light gray,  textures ranges from granititic to serate.   The age dates indicate that this
K-Ar age ranges on biotite of  65 m.y.  K-Ar ages on muscovite 67.2 m.y.
Granititic rocks undivided
Cretaceous and (or) Tertiary
Rocks of uncertain age occur in four smaller epizonal plutons of granodiorite and tonalite.  Color is medium to dark gray, grain size is medium, texture is granititic.  Mafic minerals are hornblende and biotite.
TKlg
Leucogabbro
Small poorly exposed intrusive of uncertain age essentially consisting of plagioclase and pale-green hornblende.  Medium to light gray, coarse to medium grained, with a granitic to seriate texture.
TKgb
Kar
Arkose Ridge Fm
Cretaceous (Eocene/Paleocene probably)
Arkosic sandstone, conglomerate, graywacke, siltstone, and shale.  Clasts consist chiefly of granitic and metamorphic rock frags, quartz, feldspar, and biotite.  Plant fragments indicate a terrestial origin.  The formation rests unconformably on Jurassic
K-Ar on biotite yields an age of 67.5 m.y.
Matanuska Fm
Well-indurated shale, siltstone, sandstone, graywacke, with subordinate conglomerate interbeds; total thickness in excess of 1200 m.   Generally dark gray and thinly bedded, mostly marine depositional environment of moderate to shallow depths.   May corr
Plant frags
Naknek Fm
Shallow marine, thin to thick bedded, intercalated strata of fossiliferous gray siltstone, shale, sandstone, and conglomerate; over 1400 m thick.   Correlates with the Root Glacier Fm of the southern Wrangell Mountains.
Jct
Chinitna Fm and Tuxedni Group (Middle Jurassic) undivided
The Chinitna is shallow marine, intercalated sequence of dark-gray shale, siltstone, and subordinate graywacke; contains numerous large limestone concretions; it is as much as 600 m thick.  The Tuxedni Group is shallow marine, well-indurated, thinly to t
Jtxc
Talkeetna Fm
Andesitic flows, flow breccia, tuff, and agglomerate; subordinate interbeds of sandstone, siltstone, and limestone.  A dominately shallow marine sequence about 1000 to 2000 m thick
Jls
Light to dark-gray, fine- to medium-grained unfossiliferous limestone; near granitic rocks recrystallized to marble.  Forms lenticular bodies, as much as 30 m thick, within the Talkeetna Fm.
Forms discordant, NE trending epizonal pluton.  Large portions have been sheared and saussuritized.  Light gray, medium to coarse grained with granitic texture.  A faint flow foliation is lovally developed.  Major minerals include plagioclase, quartz, k-
K-Ar ages on biotite range from 99.4 to 148.5; on muscovite they range from 129 to 146 m.y. One biotite age of 67.8 m.y. was probably reset by a more recent event
Middle to Late Jurassic
Dominately granodiorite but includes minor amounts of tonalite and quartz diorite.  Medium to dark gray, medium grained, and in undeEromed rocks have granitic texture.  Mafics includes biotite and hornblende.  Ne-trending secondary foliation is present i
K-Ar ages on biotite range from 144 to 174; on hornblende range from 154 to 167.  A zircon age of 125 was also determined using fission track.
Jgdm
Migmatite border zone of Granodiorite
Forms a terrane of poorly exposed, intricately intermixed contact schist, amphibole, and small dikes and veinlets of granodiorite.
Jmrb
Middle to Late Jurassic metamorphic age
Contact metamorphosed marble bed more than 40 m thick within migmatitic border zone.    The rock is white, coarse to medium grained with prophyroblastic cystals of garnet and diopside.
Dominately quartz diorite but also includes diorite and tonalite.  Large portions have been intensively sheared and altered.  Fresh rock is medium to dark greenish gray, medium to coarse grained, and has granitic texture.  Where altered, the quartz diori
Jam
amphibolite
Middle to Early Jurassic metamorphic age
Dominately amphibolite but includes subordinate amounts of greenschist and fgoliated diorite.  Amphibolite is generally dark greenish gray, medium to coarse grained, but fine-grained varieties also occur.
K-Ar age on hornblende of 176.6 m.y.
Jmb
marble
White, medium- to coarse grained, massive interbeds within the amphibolite terrane of Jam.  Contains subordinate amounts of garnet and diopside.
greenstone
Dark greenish gray, fine-grained, generally structurless rock.  Oringinal minerologiy was pyroxene, amphibole, and plagioclase which altered to chlorite, epidote, serpentine, calcite, and minor sericite and quartz.
Jpmu
Plutonic and metamorphic rocks, undifferentiated
Intermixed mosaic of most of the previously  discussed Jurassic  metamorphic and plutonic rocks (Jtr, Jgd, Jgdm, Jqd, Jgs, and Jps).  Two rock types, amphibolite and sheared quartz diorite, dominate the terrane.
Trv
Basaltic metavolcanic rocks
Shallow water marine unit consists of amygdaloidal metabasalt flows with very subordinate amounts of thin interbeds of metachert, argillite, metavolcaniclastic rocks, and marble.  Minimum thickness of the unit is 800 m.  Metabasaltic flows are as much as
Basaltic to andesitic metavolcanic rocks
Pennsylvanian (?) and Early Permian)
Rocks of this unit form an interlayered heterogeneous, dominately marine sequence over 5000 m thick.  Primarily consists of metamorphosed flows and tuffs of basaltic and andesitic compositions.  Mudstone, bioclastic marble, and dark-gray to black phyllit
Pls
Pennsylvanian (?) and Early Permian ?)
Forms lenticular interbeds, as much as a few tens of meters thick, within basaltic to andesitic late Paleozoic metavolcanogenic sequence (Pzv).  Rock is light gray to white, medium to coarse grained, thick-bedded to massive marble.
Poorly preserved and generally unidentified crinoid columnals, brachipods, bryozoans, and rarely corals.
Sedimentary and volcanic rocks, undivided
These rocks comprise a section of intercalated argillite and graywacke, pebble conglomerate, and flows and dikes of andesite to latitic feldspar porphyry.  The argillite and fine-grained graywacke are thinly to moderately thickly bedded and generally are
well-preserved fossils of Buchia rugosa from argillite indicating a Late Jurassic age.
Argillite and lithic graywacke
These rocks occur in a monotous, intensely deformed flyschlike turbidite sequence, probably several thousand meters thick.  The rocks are highly indurated, and many are sheared and pervasively cleaved.  Most cleavage is axial plane cleavage.  The argilli
poorly preserved fossils of  Incoceramus sp.; a block of Buchia-bearing limestone was found in float.
Metabasalt and slate
Shallow marine, interbedded sequence of amygdaloidal metabasalt flows and slate.  Sequence is tightly folded along with Kag and slightly metamorphosed and unv\evenly sheared.  The metabasalt is dark greenish gray, aphanitic, with numerous amygdules.  The
Monotis subcircularis and Heterorstridium sp. in argillite beds
DSga
Graywacke, argillite, and shale
Silurian ? to Middle Devonian
This unit is poorly known.  The component rocks identifed are medium to dark gray, sheared and tightly folded with vertical dips, and occur intercalated in beds as much as 1 m thick.
Jta
Crystal tuff, agillite, chert, graywacke and limestone
Shallow to moderately deep marine sequence, tightly folded and interally faulted, at least several thousand meters thick.  Tuff is light to dark gray, locally with a greenish tint and weathers to brown.  It is massive with obscure rhythmic laminations an
Sedimentary rocks, Undivided
Shallow marine sequence of thinly bedded calcareous sandstone, siltstone, claystone, minor conglomerate, and thick-bedded to massive clastic limestone;  over 100m thick
Knl
CZum
Cambrian and/or Precambrian
Serpentinite and greenstone intruded by gabbro and diorite
LG002
Livengood
CZwa
Wickersham unit--Maroon and green argillite
Early Cambrian and Late Proterozoic
Maroon and green argillite, phyllite, quartzite, graywacke, siltite, and phyllite.  Unit is characterized by the relative lack of grit except in the far western part of the quadrangle
Maroon and green argillite, grit, quartzite, siltite, graywacke and phyllite--As mapped includes thin beds of dark limestone, which are probably equivalent to unit CZwl, as mapped in other areas, but which are areally restricted and are not mapped separa
Wickersham unit--Grit
Grit, quartzite, phyllite, and slate.  Differs from other grit units in that it contains chert. Includes limestone interbeds (l) that lithologically resemble subunit CZwl Livengood Area
CZwl
Wickersham unit--limestone
Dark-gray arenaceous limestone
Wickersham unit--Dark limestone
Sparsely or non-arenaceous limestone
Dc
Cascaden Ridge unit
Middle Devonian
Shale, siltstone, sandstone, conglomerate, and minor limestone
Dcb
Dq
Quail unit
Conglomerate, phyllite, calc-phyllite, siltstone, and sandstone
Lost Creek unit
Devonian and Silurian
Limestone and varied sedimentary rocks
Dlc
Dsl
Schwatka unit--Limestone
Middle and Early Devonian
DSt
Tolovana Limestone
Middle Devonian to Early? Silurian
Limestone and rare dolomite
Dsv
Schwatka unit--Mafic volcanic rocks
Mafic volcanic rocks and minor clastic sedimentary rocks
Ka
Alaskite
Exposed at Raven Creek Hill
Kd
Dikes
Bodies ranging in composition from granite to diorite
Pedro Dome and rocks in its vicinity
Vrain unit
Early Cretaceous and/or Jurassic
Pyritiferous shale and minor siltstone.  Not flysch, thought by Tom Dutro to be equivalent to upper part of Glenn Shale.
KJvr
KJw
Wolverine unit
Quartzite and interbedded shale and siltstone
Minto unit
Late Cretaceous?
Siltstone, mudstone, graywacke, quartzose sandstone, and plant-fragment-bearing siltstone
Kmo
Quartz monzonite, monzonite, and syenite
Comprises Sawtooth, Wolverine, Elephant Mountains, and Huron Creek plutons
Syenite
Roy Creek stock
Kwcc
Wilber Creek flysch unit, coarse-grained
Early Cretaceous; Albian
Polymictic conglomerate, conglomeratic graywacke, and shale
Kwcf
Kwcs
Wilber Creek flysch unit, fine-grained
Shale, siltstone, and graywacke
MzPzp
Phyllite, amphibolite, greenstone, and diorite
KJvr?
MzPzr
Raven Creek Hill unit
Metasedimentary gneiss, mica schist, phyllite, and hornfels
TPza
Ofs
Fossil Creek Volcanics--Shale
Shale, chert, and limestone intruded by gabbro
Ofc
Ofv
Fossil Creek Volcanics--Alkali basalt
Alkali basalt, agglomerate, and volcanoclastic conglomerate.
Old
Livengood Dome Chert
Late Ordovician
Chert, siliceous slate with rare greenstone and limestone
Och
PDms
Metamorphic and sedimentary rocks
Permian to Devonian?
Black and greenish-gray siliceous slate, chert, siltstone, debris flows, and greenstone
PMs
Greenish-gray siliceous slate, quartzite, chert, and greenstone
Permian to Mississippian
Argillite, siltstone, sandstone, and minor conglomerate
Chatanika unit
Allochthonous, garnet-bearing quartz-biotite-muscovite schist, and quartzite.  Primarily epidote-amphibolite facies rocks, but also includes eclogitic rocks
Pze
Mafic igneous rocks
Paleozoic and/or Late Proterozoic
Includes minor interlayered sedimentary rocks
Qab
Abandoned or inactive flood plain deposits
Includes natural levees on streams in the Minto Flats
Qaf
Alluvial fan deposits
Qd
Sand dune deposits
Reworked creek gravels in placer mining areas
Qlc
Loess and colluvium
Includes minor upland alluvium
Swamp deposits
Qsu
Reworked silt, undifferentiated, and organic deposits
Includes swamp deposits
Gravel, sand, and silt
Holocene to Pliocene
Poorly consolidated deposits
SZa
Amy Creek unit
Silurian? to Late Proterozoic
Siliceous dolomite, chert, and basaltic greenstone, minor limestone, shale and siltstone
Olivine basalt
Tgp
Peraluminous granite
Cache Mountain pluton
Felsic granitic rocks
Tertiary and/or Cretaceous
Small intrusive bodies in the upper Wilber Creek area
Vault pluton
Cascaden Ridge pluton
Monzonite(?) or Monzodiorite(?
Paleocene?
Northeast of Tolovana Hot Springs pluton
Tqm
Quartz monzonite
Tolovana Hot Springs pluton
Trc
Black shale and chert
Triassic
Trm
Gabbro and diabase sills and dikes.
TrMrs
Rampart Group--Sedimentary rocks
Argillite, chert, graywacke, shale, and limestone
TrMts
TrMrv
Rampart Group--Igneous rocks
Intrusive and extrusive mafic igneous rocks, and a few intermixed sedimentary rocks
JTrtmu
Calcareous phosphatic shale and limestone
Includes minor calcareous sandstone and granule conglomerate
Trgl
Volcanic and sedimentary rocks, undivided
Oligocene and Eocene
Conglomerate, sandstone, shale, and basalt
Zf
Fairbanks schist unit--undivided
Late Proterozoic
Greenschist facies muscovite-chlorite schist, quartzite, and phyllite.  Locally, divided into:
PzZyqs
Zfc
Fairbanks schist unit--Cleary subunit
Facies characterized by white felsic schist, micaceous quartzite, chloritic or actinolitic greenschist, greenstone, and marble
Zwg
Grit
Bimodal quartzite, gray and olive-gray greenschist-facies argillite.  Unit age is considered to be Hadrynian
Gravel, sand, silt; gray or buff, uncolsolidated, well-stratified; mapped only in valleys of major streams.  Includes gravel, sand, and silt of low terraces
BD002
Big Delta
Alluvium and colluvium
Boulders, gravel, sand, silt, and angular rock fragments.  In large river valleys contains much perennially frozen organic silt and peat.
Loess
Silt, eolian; light brown to brownish gray, unconsolidated, well-sorted, massive to poorly stratified; locally mottled by iron stains.  In places contains venefacts.  Thickness ranges from 1 to 50 m.
Sand
Sand, eolian; yellowish brown to grayish orange, light gray and olive gray, unconsolidated, forms dunes as much as 21 m high and dune fields 1 or more square kilometers in area.  Sand is commonly overlain by as much as 1 m of loess.
Qsp
Silt and peat
Organic silt deposited in swamps, black or mottled gray and brown.  Mostly perennially frozen.  Only the large areas of this unit in the vicinity of the Tanana valley are mapped
Abandoned floodplain alluvium
Unconsolidated silt, sand, pebbles, and cobbles, in well-stratified layers and lenses.  Light to dark gray and buff to brown; includes much organic material and grades into swamp deposits in poorly drained ares.
Fan deposits
Sand, gravel, and cobbles, in fairly well-stratified layers and lenses.  Primarily distal segments of  undifferientiated glacial outwash fans, mantled with loess.
Qm
Moraine deposits
Boulders, gravel, sand, and silty sand, in terminal moraine, lateral moraine, moraine in cirques, and ground moraine of several different ice advances.
Qdo
Outwash of Donnelly glaciation
Gravel and sandy gravel, light yellowish-brown to gray, moderately to well-rounded, in unconsolidated well-stratified layers and lenses
Qdlm
Morainal deposits of Delta glaciation
Till, sandy, yellowish-gray to light reddish-brown, unconsolidated, unstratified.  Gravel is angular to well-rounded, 2 cm to 24 cm in diameter
Qdlo
Outwash of Delta glaciation
Gravel silty or sandy, with lenses of well-sorted sand; light yellowish -brown.  Gravel well-rounded, poorly to moderately well-sorted in unconsolidated moderately well-stratified layers
Conglomerate and minor amounts of sandstone; yellowish-gray to reddish-brown, poorly consolidated, well-sorted.  Conglomerate particles, mostly well-rounded, up to 8 cm in diameter, characteristically iron-stained.
Coal-bearing formation
Sandstone, siltstone, claystone, and conglomerate, light-yellowish-gray to light-reddish-brown, poorly consolidated, easily eroded.  Conglomerate particles mostly well-rounded quartz and chert as much as 4 cm in diameter.  Lignitic coal layers as much as
Conglomerate, Sandstone, Siltstone, Shale
Light gray, poorly consolidated, poorly bedded.  Conglomerate clasts are well-rounded to fairly angular and extremely variable in size ranging from granules to 1 m boulders of several types of granitic rock, gneiss, white quartz, and rarely schist.  Sand
Quartz monzonite to granite; medium to coarse grained; equigranular to porphyritic; massive without linear or planar fabric or microfabric; commonly weathered and crumbly.  Only plutons with Tertiary K-Ar dates are included in this unit.  Plutons that ma
Felsic igneous rocks
Lava, shallow, intrusives and dikes and sills.  Lava in eastern part of quad, gray with smokey quartz, sanidine, plagioclase, biotite, and hornblende phenocrysts.  Phenocrysts may be as long as 2 - 5 mm.  Some are 10 mm long.  Rock generally fractured an
Granodiorite to Quartz Monzonite
Medium grained; equigranular to porphyritic; massive without linear or planar fabric.  The rocks contain biotite, hornblende, muscovite, with biotite the most common mafic mineral.  The rocks in this unit are not  radiometrically dated
Medium to coarse grained; mostly equigranular; massive without linear or planar fabric.  The rocks contain biotite is the most common mafic mineral; hornblende is less common.
K-Ar ages are Cretaceous
Diorite and Gabbro
Diorite medium gray, medium grained; dominately pyroxene, biotite and plagioclase; amphibole may be absent; in places quartz diorite; locally may be gabbro; generally massive.  Unit also includes undated dike and lenslike mass of dark-greenish gray, medi
Kp
Quartz-Orthoclase Porphyry
Pink to tan weathering.  Quartz and Carlsbad-twinned orthoclase occur as large as 1 cm; euhedral phenocrysts in aphanitic to fine-grained groundmass; sericitzed.
K-Ar on potassium feldspar
Pgc
Greenstone and Chert
Greenstone is light to dark green or greenish gray, greenish red, or greenish black; fine to coarse grained;  mostly massive with weakly developed foliation in places.  Chert is green, light, and dark gray, red, and mottled green and gray; massive, close
Radiolarians and conodonts in red chert
JPzsgs
Pu
Periodotite, partly serpentinized
Dark green to black; weathers a reddish orange brown; massive.  Diabase and diorite inclusions, commonly meters in diameter. A zone of quartz and magnesite, with some dolomite, 1 to 50 m thick. The silica-carbonate rock is bright orange, orange brown, or
JPsu
Pq
Quartzite with some Phyllite, Micaceous Quartzite, Marble, and Calc. Qtz. Schist
Quartzite and lesser phyllite, micaceous quartzite, marble, and calcareous quartz schist.  Quartzite is tan, red, maroon to purple, and black and commonly  finely banded.  Mostly fine-grained and in places closely folded.  Locally has abundant, fine, dis
Cataclastic rocks
Mostly mylonite schist and mylonite gneiss; gray, light green and tan; fine to coarse grained; dense and hard to soft  and crumbly; fluxion structure common; neomineralization and crystalization evident.  Rocks mostly quartzitic and feldspathic with mino
MDtm
Pzsg
Semischist, greenschist, quartzite, phyllite, marble, and greenstone
Semischist or sheared grit; greenish gray or gray and fine to coarse grained; very quartzitic to very feldspathic; clear, gray, or bluish-gray quartz graine 1 to 5 mm in diameter characteristic; interlayered with quartz-chlorite mica schist and others co
Pzq
Quartzite, Meta-Argillite, Phyllite, Slate, and Marble
Quartzite commonly black but varies widely in color.  Locally, color changes due to contact metamorphism.  Interlayered with black or dark-gray meta-argillite.  Phyllite, marble, and quartzite more commonly occur in the upper part of the formation but ma
Calcareous Phyllite, Marble and Phyllite
Light to medium gray, fine to medium grained, thin layered and well foliated, commonly crumbly.  Characteristically cut by abundant carbonate-quartz veins and veinlets; locally forms low tors.  Age unknown, but stratigraphic relationships suggest early P
Pzkcp
Schist
Quartz-mica schist with marble and quartzite, calcareous diopside schist, quartz-feldspar rock; and amphibole.  Sillimanite is locally abundant near the Salcha River and staurolite, andalusite and kyanite also occur.
Gneiss
Gray and weathers tan; locally orange brown where altered; mostly medium grained equigranular; respresentative mineralogy is strained quartz, plagioclase, potassium feldspar, red-brown biotite and sillimanite; garnet, tourmaline, zircon, and apatite are
PzZyg
Pzu
Light green, greenish gray, or black and less commonly tan, brown, or yellow green; Occurs as small foliated masses infolded with amphibolite facies gneiss and schist.  Original rock was peridotite which has been regionally metamorphosed to amphibole, ch
Diorite
Medium gray to medium dark gray, fine to medium grained; dark-green to pale-brown hornblende, red-brown biotite abundant in some localities; foliation well-developed locally.
PzpCsq
Schist and Quartzite
Quartz-muscovite-biotite schist, quartz-muscovite schist, quartzite, and amphibole schist; locally garnetiferous.  Upper greenschist to lower amphibolite facies.  Age unknown.  Unit subdivided on published OFR98-133 into PzZysa and PzZysq.
Quartzite  and Schist
Quartzite, feldspathic quartzite and quartz-mica schist, medium light gray to medium gray.  Quartzite, some shows original bedding, dominates the section.  Quartz-biotie schist is commonly; most of the unit is garnetiferous; Upper greenschist to lower am
PzpCa
Augen Gneiss
Augen most commonly of white potassium feldspar, range in size from 1 to 10 cm long, most about 4 cm long.  Biotite is scarce to abundant.  Foliation layers containing biotite bend around augen.  Age unknown.
PzpCg
Gneiss and Quartzite
Coarse to fine grained gneiss and quartzite; well foliated and banded to massive without banding; locally cataclastic;  ranges from peltic with abundant sillimanite to gneisses of probable igneous origin.  All rocks are well foliated, and dominant foliat
PzZypg
Flood-plain alluvium
Well-stratified layers and lenses of unconsolidated gray silt, sand, pebbles, cobbles, and boulders;  occurs in two facies 1) gravelly facies 2)  silt and sand facies.  Both occur on the Tanana River east of the mouth of the Chena and on other streams in
FB002
Fairbanks
Dark-brown to black peat and silt more than 5 feet thick in some areas.  Perenially frozen and contain lenses and veinlets of clear ice.
Landslide debris
Chaotic masses of angular fragments of shale, sandstone, and conglomerate, clay, sand, gravel, and schist  embedded in a matrix of silt, clay, and gravel.
Reworked creek gravel
Placer-mine dredge tailings derived from buried creek gravels.
Qbc
Basaltic cinders
Cinder cone from late Pleistocene or Recent eruption at north base of mountain southwest of Buzzard Creek.  Unconsolidated poorly sorted aggregate of irregular to subrounded fragments of scoriaceous to dense basalt.
Qcs
Abandoned flood-plain alluvium
Well-stratifed layers and lenses of unconsolidated gray silt, sand, pebbles, cobbles, and boulders.  Occurs in two facies: 1)  coarse gravelly alluvium and 2) silty alluvium containing 95% silt and 5% sand.
Well-stratified layers and lenses of gray to brown coarse and and pebble, cobble, and boulder gravel.
Qdr
Dune Sand, reworked
Organic silty sand underlying undrained depressions and old lake or pond beds; derived from near by sand dunes.  Permafrost and considerable ground ice probably present at shallow depths.
Qrm
Morainal deposits of Riley Creek Glaciation
Unsorted and unstratified glacial till with silt cover 1/2 foot thick.  Silt, sand, and gravel containing boulders more than 3 feet in diameter.  Coarse fragments angular to rounded.  Permafrost present, ice content low to moderate.
Qro
Outwash of Riley Creek Glaciation
Well-stratified well-sorted porous and very permeable gray to pale yellowish brown sandy gravel containing lenses of coarse well-sorted sand.
Qtf
Torrential fan deposits
Interfingering cobble and pebble gravel, mudflow deposits, and minor amounts of silt and sand, bordering the foothills.  Average coarseness decreases away from foothills.
Fairbanks loess
Massive, homogeneous eolian silt on upper slopes and hilltops.  Well sorted, less than 10 % clay; grains angular, consist mostly of quartz, feldspar, and mica.  Locally cemented by iron oxide, locally calcareous.  Thickness ranges form 3 to 200 feet.  Co
Perennially frozen silt, undifferentiated
Massive, homogeneous unconsolidated, well-sorted silt of eolian origin containg less than 10% clay, locally rich in organic silt and larger organic fragments.  Inorganic components are angular grains of quartz, feldspar, and mica, locally cemented by iro
Large quantites of plant and animal remains
Dune sand
Well-sorted angular to round, moderate yellowish-brown eolian sand consisting of yellowish-white, clear to opaque quartz grains (65 to 85%) but including some dark-gray to black rock fragments.
Qhm
Morainal deposits of Healy Glaciation
Unstratified glacial till with silt cover 1/2 foot to 3 feet thick.  Silt, sand, and gravel with boulders more than 3 feet in diameter.  Coarse fragments angular to rounded.
Qho
Outwash of the Healy Glaciation
Coarse, clean, well-sorted, well-stratified gray to yellowish-brown porous and very permeable gravel with layers and lenses of coarse clean sand.
Qha
Alluvial fan deposits contemporaneous with Healy Glaciation
On the Dry Creek fan these deposits consist of well-stratified gray to brown pebble, cobble, and boulder gravel with layers and lenses of coarse sand, and range from fine clean gravel with pebbles 1/2 inch to 3 inches in diameter at the north end of fan
Qdm
Morainal deposits of Dry Creek Glaciation
Mapped from aerial photos based on topographic expression.  Probably similar to morainal deposits of Healy Glaciation but somewhat more weathered and eroded.
Outwash of Dry Creek Glaciation
Similar to outwash of Healy Glaciation on same stream but more weathered and eroded, and overlain by thicker deposit of windblown silt.
Qda
Alluvial fan deposits contemporaneous with Dry Creek Glaciation
Similar to alluvial fan deposits of Healy Glaciation on same stream but more weathered and eroded, and overlain by thicker deposit of windblown silt.
Qbm
Morainal deposists of Browne Glaciation
Coarse sand and gravel, with abundant blocks of granite, gabbro, and conglomerate several feet on a side.  Small areas at an altitude of 2200 feet west of  Windy Creek and 5000 feet southeast of Gold King Creek consist  largely of boulders and blocks.  I
Buff to reddish-brown poorly consolidated pebble to boulder conglomerate and coarse sandstone, with interbedded mudflow deposits, thin claystone layers and local thin lignite beds.  Maximum thickness is 2000 feet.
Tertiary, Miocene? to Eocene?
Poorly consolidated, readily eroded pebbly sandstone, claystone, and subituminous coal, in synclinal basins in the foothills of  the Alaska Range between Nenana River and Dry Creek.  Pinches out northward and is overlapped unconformably by Nenana Gravel.
Mt
Predominately quartz-microcline-sericite schist and augen gneiss, gray in color, consisting of a coarse facies having large deformed phenocrysts of microcline, quartz and rare albite 0.1-1 inch in diameter; interbedded with a fine facies consisting of an
Syringopora
Tolovana (?) Limestone
Middle Silurian to Middle or early Late Devonian
Thick-bedded to massive, fine-crystalline to lithographic, medium dark bluish-gray limestone of unknown thickness.  Weathers buff to yellowish-brown.  Chert rare or absent.  Correlated on basis of lithology and geographic trend.
nc
Nilkoka Group- Chert and siliceous shale
Uncertain but believe to be Precambrian or early Paleozoic
Chert is hard, thin bedded to blocky, locally cut by shear planes, medium light gray or rarely nearly white or black with thin color layering; commonly stained yellow or red by iron oxide from weathering; forms reddish soil.  Interbedded siliceous shale
correlated to Mertie's (1937) unit B on basis of fossils (Cambrian or Ordovican)
ng
Nilkoka Group-  Grit, argillite, quartzite, and limestone
Interbedded grit and varigated clay slate, quartzite, and phyllite, with rare siltstone beds and a few fine-grained lenticular limestone beds as much as 5 feet thick.  Color of fine-grained rocks predominately green but mottled by red through pale olive
bc
Birch Creek Schist
Uncertain but believe to be early  Paleozoic or Precambrian
Light- to dark-gray, reddish-brown to tan-weathering schists, predominately quartz-sericite schist and micaeous quartzite.  Includes mu-bio schist, garnet-mica schist, calcite-and dolomite-bearing schist, chloritic and graphitic schist, amphibolite, impu
120 m.y. to 1,170 m.y.
Mzi
Probably Mesozoic but may be early Tertiary
Dikes and stocks of granite, granodiorite, dacite, and granite porhyry, intruded into schist formations of the Yukon-Tanana uplands and the Alaska Range.  Unconformably overlain by the coal-bearing formation (unit Tcb).
Dmu
Mafic and Ultramafic rocks
Devonian (?)
Ophitic diorite and serpentinized periodotite make up the Wood River Buttes.  Ore minerals constitute about 5% of the diorite.  Wood RIver Buttes are on a projection with mafic and ultramafic rocks in the Big Delta quad.  There is an intense linear posit
Dark-gray and black or brownish oline basalt, closely jointed and deeply weathered with local pillow or columnar structure;  on lower slope  of hills near Fort Wainwright.
Qt4
Till, Cirque glaciation
Quaternary?
Unsorted boulder to clay-size  particles.  Moraine forms locally present, restricted to cirques
TN002
Tanana
Qt3
Till
Unsorted boulder to clay-size particles, includes long low lateral moraine on Halu Creek
Qt2
Unsorted boulder to clay-size particles, lowest moraine on Halu Creek
Qt1
Unsorted boulder to clay-size particles, farthest down valley moraine on lower Halu Creek.
Till, undifferentiated
Unsorted boulder to clay-size particles, no clear morainic forms.
Recent alluvium
Sandy gravel and sandy silt, forms flood plain of modern rivers and streams.
Gravel, silt, and sand, commonly occur at mouth of small side canyons.  Includes some colluvial deposits.
Qbg
Low-level bench gravel of Minook Creek
Gravel and sand on bench along lower parts of Minook and Hunter Creeks
Qtr
Gravel, silt, and sand near mouth of Fleshlanana Creek
Qags
Older alluvium
Coarse, silty sand and fine gravel; generally forms terrace sloping up and away from floodplains of streams and rivers
High-level gravel
late Tertiary or early Quaternary
Well packed gravel, caps hills in vicinity of Rampart
Qcal
Colluvium and alluvium, undifferentiated
Silt and sand mantling broad, flat valleys
Qrs
Recent slide and slump deposits
Very fresh, unmodified slumps and earthflows (Occurred about 1940).
Qls
Older landslide deposits
Slumps and earth and rock slides
Colluvium, undifferentiated
Predominantly silt, with some sand and gravel.
Qta
Talus
Angular boulder rubble in cirque.
Well-sorted silt
Qess
Sand and silt
Well-sorted sand, commonly in subdued dune forms
Qb
Rock-defended terraces on Minook Creek
Erosional benches along east side Minook Creek
Qat
Altiplanation terrace
Flat, even surface, formed on bedrock hilltops generally above 600 m
QTa
Andesitic lava
Late Tertiary or early Quaternary
Light to very ligry-gray vesicular lava.  Removed from final map
Rhyolitic volcanic and sedimentary rocks
Tertiary?
Rhyolitic lava and breccia.  Tuff and welded tuff common.  Cherty rocks minor, thin-bedded or in nodules.
early Tertiary and Miocene
Interbedded polymictic pebble-cobble-boulder conglomerate, grit, and sandstone, with siltstone, shale, and lignite.
Late Cretaceous and Early Tertiary
Dacite flows, may include tuff and andesite.
TKvd
KJcs
Clastic sedimentary rocks
Late Jurassic and Cretaceous
Graywacke sandstone, quartzitic sandstone, quartzite, siltstone, shale, slate, slaty argillite, and polymictic conglomerate.
JMms
Mafic and sedimentary rocks
Jurassic? to Mississippian
Rampart Group volcanic and sedimentary rock sequence
TrMtsu
Slaty shale, siltstone, graywacke, and conglomerate
Moderately well-indurated, medium- to dark-gray shale, commonly weakly foliated to slaty, and in part phyllitic.  Well indurated, medium- to medium-drak-gray siltstone, in part argillite.
TrPs
Pzar
Argillaceous rocks
Permian or Middle to Late Devonian
Thin-bedded siltstone, slate, and phyllite, thick-bedded argillite, and minor laminated sandstone.  Metamorphosed to low grade.  Not on published OFR98-133
Calcareous clastic rocks
early Paleozoic, possibly Devonian
Medium-gray siltstone and very fine-grained sandstone, largely calcareous and generally schistose.  Not on OFR98-133
Dq?
Pzw
Quartz wacke
Poorly sorted sandstone, granule conglomerate, siltstone, and semischist.  Not on OFR98-133
Dq2?
Pzsr
Schistose rocks
middle Paleozoic?
Chiefly white, light- to medium-gray, silvery gray, and brownish gray, fine- to coarse-grained quartz-mica-grarnet schist.  Unit apparently conformable with unit Pzl, but contact is poorly exposed.
Limestone, greenstone, and schist
Ordovician(?), Silurian, and Devonian
Dominantly light- to light-medium-gray partly dolomitic limestone and dolomite.  Basaltic greenstone and partly calcareous chloritic schist are associated sequentially or interbedded with the carbonate rocks
DSt?
Ordovician or Silurian
Partly altered mafic lava and tuff, slate, slaty shale, phyllite, tuffaceous limestone, cherty schist, and chert.  Not on OFR98-133
Dtr
Limestone, dolomite, greenstone, and schist
Silurian or Devonian
Limestone, dolomitic limestone, partly silicified dolomite, basaltic greenstone, and chloritic schist.  Similar to unit Pzl south of Yukon River.
DSls?
Chert
Late(?) Ordovician
Light- to medium-gray chert.
Cal
Argillite, slate, quartzite and grit
probably Cambrian, possibly in part preCambrian
Medium- to dark-red or maroon, light- to medium-green and grayish-green, and medium-gray argillite and slate.  Light yellow-brown to light-gray quartzite and grit.  Not on OFR98-133
Schist, quartzite, phyllite, and slate
early Paleozoic(?) and preCambrian(?)
Light- to medium-gray and silvery gray quartz-mica schist, light- to medium-gray quartzite, light- to dark-gray slate and phyllite.  Not on OFR98-133
early Tertiary
Light-gray biotite granite, only at Manley Hot Springs
K-Ar(?) 62 Ma
TKq
Early Tertiary-Late Cretaceous
Light- to vey light-gray quartz monzonite, may range to granite
K-Ar(?) 61.8 Ma
Quartz monzonite, granite, monzonite, and possibly granodiorite
K-Ar(?) 92, and 90 Ma; 104 Ma
Mafic rocks
Gabbro, diorite?  Not on published OFR98-133
Ksp
Serpentinite and mafic rocks
Serpentinite, diabase-gabbro and some metadiorite.  Not on published OFR98-133
Jpu
Serpentinized peridotite and dunite
Mg
Globe unit
Light-gray quartzite.  Massive or thinly interbedded quartzite and medium- to dark-gray slate, phyllite, and minor laminated claystone.  Age fro date of Trm intrusive and lithologic and stratigraphic similarities to Keno Hill Quartzite in Yukon.
Mgq
Dcg
Beaver Bend unit
Devonian?
Polymictic light- to medium-gray chert pebble conglomerate, graywacke, siltstone, and slate
Unidentifiable plant fragments
bedrock of unknown type or age
Rubble of metasiltstone and chert, believed to be older than TKf.  Also includes an outcrop of white, very fine grained quartz sandstone
KH002
Kantishna River
Da
Augen gneiss
Biotite-bearing felsic augen gneiss
U/Pb age 387 +/- 43 Ma, protolith(?) age
CI002
Circle
Not on OF98-133
KH003
Gabbro and diorite
Serpentinite with some diabase, gabbro and mafic volcaniclastic rocks
Serpentinite with some diabase, gabbro and mafic volcaniclastic rocks.  Not on OF98-133
MzPzc
Circle Volcanics
Triassic and Penn. or Mississippian
Diabasic gabbro, basalt, diorite, ultramafic rocks, chert, and tuff.  Rare limestone.  Probably correlative with Rampart Group
Radiolarians from chert of Pennsylvanian, Mississippian, and Triassic age.
Mesozoic and/or Paleozoic
Green, olive-green, or greenish-brown, medium- to very coarse-grained, porphyritic diorite.
Serpentinized periodotite
Gray, green, and greenish-gray to greenish-black, fine- to coarse-grained serpentinized peridotite.
Pzug
Ultramafic and mafic rocks and greenstone
Mostly greenish-black serpentinized peridotite.  Greenstone consists of metamorphosed basalt and tuff.
Quaternary and/or Tertiary
Andesitic rocks
Tertiary and/ or Cretaceous
Andesite and trachyandesite are medium to light green and grayish green and weather to dull brown and brownish green;  fine to very fine-grained, prophyritic and glomeroporphyritic, abundant plagioclase phenocrysts 5-6 mm.
TKf
Light-gray weather, gray ot tan fine- to coarse-grained quartz porphyry.  Hypabyssal(?)
Felsic extrusive rocks and tuff
Very light to light gray, yellow and pink to red, mostly deeply weathered and in part iron-stained.  Rhyolitic and andesitic rocks are very fine-grained to aphanitic, porphyritic in part;  tuff resembles rhyolitic rocks may be welded in places
Mostly light- to medium-gray, hypidiomorphic granular to porphyritic granite
A number of K-Ar mineral ages (see Wilson and Shew, 1981), virtually all early Tertiary, 58 to 65 Ma
Monzonite, quartz monzonite, syenite, diorite, and quartz diorite; generally light to medium dark gray and weather to various shades of brown and gray
TKr
Rhyolitic volcanic rocks
Rhyolite porphyry is light to very light gray, mostly deeply weatered to light to medium yellow and reddish brown;  very fine-grained, small phenocrysts of smoky quartz and kaolinized feldspar
Felsic volcanic rocks
Diabase and basalt
Triassic (?)
Light- to medium-green and weathered to various shades of yellowish brown, reddish brown, and brown diabase and basalt.  Diabase is medium to coarse grained, in part porphyritic, very hard and breaks into angular blocks; basalt is very fine grained to ap
PzpCb
Basalt and limestone
Dark-greenish- or bluish-gray, medium-fine-grained calcareous basalt, having locally well-developed pillows.  Thin limestone layers at the base of the basalt.  Upper units in basalt amygdaloidal, overlain by greenish-brown breccia of calcareous basalt ha
Foliated basaltic lava, tuff, slaty shale, phyllite and some limestone and chert
Not on OFR98-133
TrPv
Basaltic and diabasic rocks, tuff, chert, argillite, slate, and rarely clastic limestone
Triassic and/or Permian
Extrusive and intrusive basaltic and diabasic rocks, tuff, chert, argillite, slate, and rarely clastic limestone.  Not on OFR98-133
Rhyolitic lava and breccia, tuff, chert and shale
Unit deleted in going to TN003
Argillite and slate
Cambrian
Maroon and green argillite and slate with quartzite, grit, and some phyllite
Cqs
Quartzite, metasiltstone, slate and grit
Range from light to dark gray ; quartzite is very fine-grained and grades to metasiltstone; blocky, irregular fractures, schistose in part; Slate and phyllite are medium gray; banded with thin silty or sandy layers in part.
Dps
Phyllite,slate, silicious siltstone, and argillite
Light and medium gray to silvery gray phyllite,slate, silicious siltstone and argillite; alters to hornfels near granitic contacts. Includes some thin limestone and calcareous siltstone.
Dp
Hornfels and gneiss
Unit removed on DOG map
Khg
MzPzaq
Argillite and quartzite
Dark-gray to black, locally quartzitic argillite, mudstone, and siltstone.  Calcareous in a few places, has local gray and black chert.  Unit includes a gray, very fine-grained limestone at one locality.  Dark greenish-gray mafic lavas, including amygdal
Conodonts in limestone range in age from Ordivician to Triassic
Eclogite
Medium-green, medium-grained, massive to foliated ecologite.  Occurs as mafic layers within unit PzpCms (NSACLASS = 5510), garnet-muscovite-schist, within which it is lumped on published map.
Greenstone
Mostly coarse diabasic gabbros.  Small individual outcrop areas of a variety of texturally and mineralogically different rocks.  Unit removed from published (OFR98-133) map and from various versions of Foster and others map.  To be reinstated.
Phyllite, calcareous phyllite and marble
Gray phyllite containing thin stringers of crumbly impure marble and black or gray quartzitic phyllite.  May includes rocks of unit Pzq (NSACLASS = 5500).
Argillite, grit, and quartzite
Paleozoic and/or Precambrian
Gray, maroon, and green slaty argillite interlayered with gray and greenish-gray grit and quartzite.  Minor limestone in southern part of exposure.
PzpCgq
Grit, quartzite and argillite
Mostly gray or greenish-gray, but may be tan, brown, or dark-gray grit and quartzite.  Ranges from fine- to coarse-grained, rarely conglomeratic, and equigranular to bimodal.  Weakly metamorphosed.  Gray to black, or greenish-gray, olive-gray, tan or bro
Trace fossil Oldhamia suggests a Cambrian or possibly Hadrynian (late pC age).
PzpCgr
Grit and quartzite
Tan or gray grit and quartzite.  Lower metamorphic grade and more calcareous than unit PzpCgq, but thought may be correlative.
PzpCm
Mafic schist
Green, chlorite-quartz-carbonate schist, associated with amphibolitic schist and mionr marble, quartzite, and pelitic schist.
PzZms
PzpCms
Garnet-muscovite schist
Medium- to coarse-grained muscovite-garnet-quartz-plagioclase schist.
Quartzite and quartzitic schists, calc-silicate and marble subunit
Light green to greenish-gray calc-silicate containing thin interlayers of crumbly, greenish-gray marble, light-green calcareous quartzite, gray and greenish-gray phyllite, and fine-grained quartzitic schist subunit of unit PzpCq, consisiting of gray or g
Mostly medium- to coarse-grained pelitic schist and gneiss, having minor interlayered quartzite and quartzitic schists and subordinate  white and cream-colored, coarse-grained marble.
Quartzite, meta-argillite and phyllite
Black, dark-gray, or gray.  Quartzite is medium-grained, thinly layered to massive.  Meta-argillite may be slaty.  Unit cut by abundant white quartz veins.  Stratigraphically overlies calcareous phyllite and marble unit (Pzm, NSACLASS = 5545)
Schist, phyllite, limestone, and greenstone
Schist and phyllite are light to medium green and light to medium gray; chlorite and mica common, partly calcareous intensely folded, interbedded with limestone. Limestone is light and medium gray, largely recrystallized; greenstone is basaltic, light to
Quartz -mica-garnet schist, with some quartzite schist, calcareous schist, marble and phyllite
KJqa
Quartzite, argilllite, conglomerate, and hornfels
Cretaceous and/or Jurassic
Mostly gray, fine- to medium-grained quartzite, interlayered with mostly gray, greenish-gray, reddish-gray, and tan argillite
MzPzat
Argillite, tuff, quartzite and conglomerate
Two parts.  One include rocks around VABM Vrain, composed mostly of argillite and minor quartzite and slaty argillite.  Second shown by ttt symbol is characterized by tuffaceous rocks associated with  black or dark-gray argillite and conglomerate.  VRAIN
Medium-gray, generally massive, locally recrystallized limestone.  Correlative with Tolovana limestone?
Stromatoporoids, corals, and condonts, result in earliest Early Devonian age.  Another part of unit(?), has corals restricting age to late Early Devonian.
Dls
Limestone and siltstone
Chiefly limestone, medium to dark gray; dolomitic in part; Siltstone is medium gray, shaly to phyllitic
Phillipsastrea or Pachyphyllum sp. (massive rugose coral) and Thamnopora sp. and Disphyllum? sp.
DSd
Dolomite and argillite
Devonian and/or Silurian
Mostly yellow-gray dolomite and moslty gray and dark-gray to black argillite, shale, and siltstone.  Interlayered with light- and dark-gray chert, yellow-gray dolomite, gray marble, and gray, fine-grained quartzite.
SZa?
Limestone, dolomite, and shale
Medium-light- to dark-gray, fine- to medium-grained limestone.  Locally limstone contains interlayered minor dolomite and dark-gray shale.  Correlates with Tolovana Limestone of Livengood quadrangle.
Sandstone, quartzite, conglomerate, siltstone, and slaty shale
KJgs
Graywacke and shale
Jurassic and/or Cretaceous
Sandstone, siltstone, and shale, medium gray, generally thin bedded
Chert and slate
Medium to medium dark gray and weathers to light yellow, tan and orange
Chert and some slaty slate
OCsl
Siltstone. limestone, phyllite and chert
Ordovician and/or Cambrian
Mostly light-medium to dark gray and weather yellow, brown and gray; thin bedded; chert rare
Livengood Dome (?) Chert
Dark-gray and black chert, gray argillite and shale and slate, gray dolomite, and minor greenish-gray, dirty and dark-gray recrystallized limestone.  Mafic volcanic rocks.
Pzcc
Chert, conglomerate and limestone
Chert and chert-pebble conglmerate most characteristic.  Chert is dominantly gray or black, locally massive, commonly brecciated.
Interlayered limestone contained late Late Devonian conodonts
Pzcg
Chert pebble conglomerate
Mostly gray chert pebble conglomerate.  Conglomerate clasts dominantly chert but include minor quartz, quartzite and rare argillite and siltstone fragments
Poorly preserved radiolarins (Spumellariina) of indeterminate age.
Limestone and chert
Two separate(?) units.  Eastern unit is light-gray to medium-dark-gray at top, mostly fine-grained, partly recrystallized, blocky fracturing limestone.  Possible algal structures.  Western unit ranges from light- to dark-gray limestone apparently interla
Pzlc
Conglomerate and sandstone
Mostly gray or tan, but locally pink or orange-brown conglomerate.  Ranges in grainsize from coarse to fine, grades into sandstone.  Sandstone is gray, tan, iron-oxide stained, commonly with "salt and pepper" appearance, fine to coarse-grained and locall
SOs
Siltstone, dolomite, chert, and mafic igneous rocks
Silurian and/or Ordovician
Gray, black, or olive-gray siltstone and argillite and mudstone.  Tan dolomite, gray to dark-gray fine-grained limestone, gray or dark-gray chert.  Mafic igneous rocks are dikes, sills, and small lense-like bodies of dark-greenish-black gabbro and basalt
PaMc
Chert, argillite, and quartzite
Penn. and/or Mississippian
Mostly black, gray, and dark-gray chert, also includes light-gray, green and white banded chert.  Rare gray, dark-gray, and black argillite, shale, slate, and siltstone and gray quartzite.  Unit form east trending belt in east Crazy Mountains.  Maybe be
Radiolarian, Albaillella sp., and Paronaella impella Ormiston and Lane of Late Mississippian age. Also Spongodiscaceid gen. nov. (tetrahedral) of latest Late Mississippian or Early Pennsylvanian age.
Gray, black, and banded chert interlayered with gray, green, olive, black, gray, and tan argillite, rare gray marble, white quartzite, and white calcareous quartzite.  Locally intruded by drak-greenish-gray to black diorite and gabbro.
Poorly preserved radiolaria, Spumellariina, possibly of Mississippian age.
Calcareous schistose siltstone and sandstone, and some phyllite
TrMtqp
Pzcs
Siltstone, slate, phyllite, and argillite
Limestone, dolomite, basaltic greenstone and chloritic schist
Limestone, dolomite, basaltic greenstone and chloritic schist; some argillite, phyllite and quartz-mica schist
PzpCd
Dolomite and marble
Gray to cream-colored massive dolomite, gray or greenish-gray marble interlayered in calcareous greenish-gray and gray quartzite and phyllite and greenish-gray calc-silicate.
Pzydm
Gravel, sand, and silt, gray, buff, or brown.  Unconsolidated, well-sorted, well-stratified.
Abandoned flood plain alluvium
Gray to brown gravel, granule to boulder size, well-sorted, well-stratified, covered with as much as 8 m of silt and organice material.  Perennially frozen.
Boulders, gravel, sand, silt, and angular rock fragments, mostly poorly sorted and poorly stratified.
Gray, tan, and brown sandy pebble-cobble gravel and pebble-cobble-boulder gravel having lenses and layers of sand, silt, and organic material.
Gravel, silt and sand, coarse clastics subangular to subrounded
Alluvial Fan deposits
Sandy gravel and sandy silt; coarse clastics subrounded to well rounded
Recent Alluvium
Flat, even surface, cut on bedrock in high areas; generally less than 2 hectares in area; thin mantle of coarse, angular rock fragments
Colluvium,  undifferentiated
Predominately silt with some larger fragments, commonly poorly sorted
Colluvium and alluvium,  undifferentiated
Elongate dunes
Gravel
Light-gray to light-yellowish-brown, pebble to boulder size, containing thin layers of sand and silt. Probably was at one time large alluvial fan of Yukon River.
Silt and sandy silt, eolian, yellowish-gray to light-gray.  Well-sorted, homogeneous, unconsolidated, generally perennially frozen.
Clay, silt, sand and gravel
Well-bedded lake deposits; at least 60 m thick
Morainal deposits, undifferentiated
Boulders, gravel, sand, silty sand in terminal, lateral, cirque and ground moraine.
Qoa
Sandy gravel and sandy silt; represents old floodplains
Organic silt deposited in swamps.  Black, dark-gray, mottled dark-gray and brown.  Mostly perennially frozen.
Silt
Probably includes both loess and solifluction mantle.  Lakes are common.  Units separated by low, elongated hills which are probably dunes
Qsf
Solifluction mantle
Silt ,some sand, and a small amount of bedrock fragments
Silt, undifferentiated and organic material
Gray, dark-gray, dark-brown or black silt, organic silt, and peat, containing local sandy lenses and layers.  Locally highly organic, generally perennially frozen.  Up to 60 m thick.
Qt (1)
Qt (2)
Qt (3)
Qt (4)
Till, cirque glaciation
Active stream alluvium
SM002
Sleetmute
Qg3
Ground and medial moraine
Ground and medial moraines interpreted from aerial photographs
Qg2
Qg1
Qou
Glacial outwash deposits
Undifferentiated glacial deposits
Undifferentiated alluvial, colluvial, and eolian deposits
Columnar basalt
Cloumnar basalt, exposed 9 mi northeast of Fortyseven Creek landing strip.
K-Ar whole-rock, 38.2 Ma
Small stocks
Small stocks, chiefly quartz monzonite, exposed in southeast corner of quadrangle.
K-Ar biotite 41.7 Ma
Sheets, dikes, and sills of rhyolite
early Tertiary, Late Cretaceous
Sheets, dikes, and sills of peraluminous biotite + muscovite rhyolite.
Six K-Ar biotite and whole-rock ages ranging from 61.5 to 70.5 Ma
Dikes and sills
early Tertiary, Late Cretaceous?
Dikes and thin sills of felsic to mafic composition mostly altered to carbonate, quartz, sericite, and clay.  Age based on intrusive relationship with late Early to Late Cretaceous sedimentary rocks (unit Kk, Kuskokwim Group).
TKvf
Felsic volcanic rocks associated with volcano-plutonic complexes, primarily composed of rhyolite tuffs and flows.  Equivalent in part to Getmuna Rhyolite of Cady and others (1955) and Holokuk Basalt of Reifenstuhl and others (1984)
K-Ar whole-rock of 43.8 Ma
Mafic volcanic rocks
Mafic volcanic rocks associated with volcano-plutonic complexes; lower unit of TKvf/TKv group.  Composed of  flows  and lesser tuff, agglomerate, and minor lahar units of dominatly mafic composition.  Intermediate and felsic rocks also present.  Named Ho
Seven K-Ar ages on plagioclase and whole rocks range from 64.3 to 74.5 Ma
Plutonic rocks
Plutonic rocks associated with volcano-plutonic complexes, monzonite, quartz monzonite, granodiorite, and granite stocks and minor dikes of mafic to felsic composition.
Six K-Ar ages on biotite and hornblende range from 63.8 to 68.9 Ma
Kuskokwim Group
Interbedded sandstone, siltstone, shale, and minor conglomerate.  Primarily submarine fan and turbidite association.
Rare fossils constrin age.
KTrg
Gemuk Group
Cretaceous to Triassic
Chiefly siltstone, interbedded with lesser amounts of chert and volcanic rock (including tuff), and minor limestone, graywacke, and breccia.
Early Cretaceous and Cretaceous fossils from map area, Late Triassic found to southwest.
MzPzgs
Holitna Group
Middle Cambrian to early Middle Devonian
Limestone, in partly dolomitized, chiefly massive but thinner bedded in upper zones.  Contains small reef-like deposits and local intraformational conglomerate and breccia.
Stromatopora sp., Favosites sp., Monotrypa sp., Spirifer (Emmanuella?) sp., Athyris sp., Productella sp., Proetus sp., trilobites, Cyathophylloid corals
Mesozic and/or Paleozoic
Two parts, tuffaceous part of unit, see KJvr also for main part of unit.  One includes rocks around VABM Vrain, composed mostly of argillite and minor quartzite and slaty argillite.  Second shown by ttt symbol is characterized by tuffaceous rocks associa
KJvt
Vitreous quartzite part of unit, mapped separately.  Light-gray, dense quartzite having a vitreous luster.  Dark-gray to black, locally quartzitic argillite, mudstone, and siltstone.  Calcareous in a few places, has local gray and black chert.  Unit incl
Quartzite and quartzitic schists, quartzite subunit
Light- to medium-gray, fine- to medium-grained relatively pure quartzite of unit PzpCq, which consists of gray or greenish-gray quartzite and quartzitic schists are dominant rock types.  Minor pelitic schist, calc-silicate, mafic schist, and rare marble
Quartzite and quartzitic schists, greenschist subunit
Green or greenish-gray, medium-grained, and massive to foliated greenschist subunit(?) of unit PzpCq, consisting of gray or greenish-gray quartzite and quartzitic schists are dominant rock types.  Minor pelitic schist, calc-silicate, mafic schist, and ra
PzpCqm
Quartzite and quartzitic schists, magnetic chlorite schist subunit
Magnetic chlorite schist subunit of unit PzpCq, consisiting of gray or greenish-gray quartzite and quartzitic schists are dominant rock types.  Minor pelitic schist, calc-silicate, mafic schist, and rare marble are interlayered with quartzite and quartzi
Pelitic schist, quartzite subunit
Pelitic schist, sillimanite gneiss subunit
PzZpg
unk
Paleozoic and or preCambrian
Various limestone symbol shown on Circle map in a variety of rock units.  No further description in text.  Includes on northern polygons of unit
Various chert symbols shown on Circle map in a variety of rock units.  No further description in text.  Assigned to Cascaden on the basis of location.
KH004
Qdl
Dune sand and loess
Both medium- and fine-grained sand dunes, massive silt deposits, particularly on windward slopes, and relatively thin veneers of silt.  The linear dunes trend SW, are commonly several km long and 8 to 20 m high, and have rounded tops.
Lacustrine deposits
Tolovana limestone
DOc
Devonian/Ordovican
Shaly rocks
pOlp
Limestone and phyllite
pre-Ordovican
Impure limestone, dolomite, greenish-gray phyllite, and silty shale, all of very low metamorphic grade.
Bedrock undifferentiated
NL003
High-terraces and slope deposits
Ta
Andesite and basalt flows
Tr
Rhyolite and dacite flows and shallow intrusive bodies
TKh
Small intrusive bodies of silicic and intermediate composition
Biotite granite
TKhs
Small intrusive bodies and thermally altered sed. rx
Small intrusive bodies and thermally altered sedimentary rocks of the Yukon-Koyokuk basin belonging to units Ks and Kg
Sandstone, shale, and conglomerate marine and nonmarine deltaic deposits in northwest part of quadrangle
Marine sedimentary rocks
Sandstone, siltstone, and shale fossiliferous marine deltaic deposits
Calcareous sandstone, siltstone, and shale prodelta deposits
Turbidite deposits
Graywacke and mudstone turbidite deposits
Andesite volcanic rocks
Jcu
Cumulate ultramafic rocks
Middle and Late Jurassic
Jht
Harzburgite tectonite
Juu
Ultramafic rocks, undivided
Basalt, gabbro, diabase, tuff, and chert
Mississippian to Triassic
TrMq
Quartzite, phyllite, limestone
Schist and quartzite
Paleozoic and Proterozoic?
Carbonate rocks
Metabasites
ls
Landslide deposits
Graywacke sandstone and mudstone -- volcanic conglomerate
Early(?) Cretaceous
Massive volcanic conglomerate mapped within unit or poorly sorted, muddy sandstone (graywacke) interbedded with mudstone.  Conglomerate appears gradational with coarse breccias and agglomerates of andesitic volcanic rocks (unit KJv, KT quad.)
Associated and gradational(?) with units containing Buchia of earliest Cretaceous age.
Cretaceous  or Tertiary
Basaltic, andesitic, and rhyolitic flows, tuffs, and breccias, and a few dacite flows; interbedded  sandstone and shale.  Flows commonly porphyritic and gently dipping. Probably greater than 500 feet thick.  (Description from RB002, should match on this
RB003
Basalt and diabase of Rampart Group
Jurassic to Permian
Basalt and diabase of Rampart Group.
Pg
Graywacke
Unit probably correlative with similar clastic rocks of the Permian(?) Rampart Group.  Unit has three parts; a) fine- to medium-grained, medium-gray to dark-greenish-gray graywacke, calcareous in part and containing some dark-gray shale fragments, b) gri
Nodosinellids (Tetrataxis), bryozoan and echinoderm debris.
MDc
Late(?) Mississippian and very latest Devonian
Medium-dark to dark-gray, thin-banded, bedded, radiolarian-bearing chert containing thin interbeds of slaty argillite.  (See unit 6080 in MD quadrangle, correlated in part.).  Mapped as Kca by Cass (1959)
see unit 7520 Od in Ruby or unit 5340, Ophir quadrangle.  Did not appear on final map.
Metamorphic rocks
Paleozoic and preCambrian?
Not described
Kku
Middle to Late Cretaceous
Chiefly marine basin and fan deposits
LH003
Lime Hills
JKw
Feldspathic wacke
Jurassic or Cretaceous
Red-weathering, locally calcareous, felspathic wacke contiaining siltstone interbeds.  Not on OFR98-133 as published.
Trb
Pillow basalt interbedded with minor argillite and chert.  See LH004 for revised unit.
Radiolaria suggest Triassic age
Mzv
Metabasalt and andesite
pre-Cretaceous
Metabasalt and metaandesite volcanic rocks
JPzk
Mzu
Undifferentiated metavolcanic and metasedimentary rocks
Altered diabase
pre-Tertiary?
Altered diabase, andesite breccia, and aphanitic to porphyritic andesite.  Age unknown, thought to be pre-Tertiary
DSab
Calcareous mudstone and limestone algal reef complex
Devonian - Silurian
Calcareous mudstone and limestone algal reef complex.  Shelf edge environment
PPl
Thick bedded limestone
Permian, Pennsylvanian?
Thick-bedded limestone, open marine shelf enviroment.  Age not reported, could be Permian, Pennsylvanian?  (Unit deleted in Bundtzen compilation[LH004])
UDl
Thick-bedded limestone, open marine shelf enviroment.  Age not reported, could be Late (Upper) Devonian?
DSls
Laminated limestone, sandstone, and siltstone
Laminated limestone, micaceous sandstone, and siltstone.  Slope environment.
Sa
Argillite
Dark-gray to black argillite with(?) chert, siltstone, and shale
Ss
Micaceous calc-sandstone
Micaceous calc-sandstone with minor limestone
SOls
Argillaceous limestone, sandstone, and shale
Silurian - Ordovician
Argillaceous limestone, calc-sandstone, and graptoloitic shale.  Slope to basinal deposits.  Unit removed, replaced largely by unit SCpl from Bundtzen (1997)
Tbr
Big River pluton
Early Tertiary?
Medium- to coarse-grained, seriate, hypidiomorphic- granular biotite granite.  Similar to and likely apothesis of Tired Pup pluton
LH002
Twf
Windy Fork pluton
middle Tertiary
Peralkaline granite in two distinct phases, an alkali feldspar granite and granite.  Overlaps into McGrath quadrangle.  Anomalous U and Th near northern margin of pluton
K-Ar biotite 29.0 to 31.1 Ma
Northern Intermediate plutons
Biotite-amphibole granite to quartz monzonite; diorite also present.
Tmp
Merrill Pass pluton
Elongate pluton that is chiefly biotite- or biotite-hornblende granite.
K-ar biotite 35.6 to 40.0 Ma, 40/39 biotite 40.0 to 42.2 Ma
Tmpg
Merrill Pass intermediate phases
middle Tertiary?
Highly variable intrusions spatially associated with Merrill Pass pluton.  Ranges from quartz diorite to granite, northern samples typically granodiorite and granite.  Larger plutonic bodies exposed in south.
Ttg
Telequana Pass pluton
Medium- to coarse-grained , seriate, biotite-hornblende granodiorite having a hypidiomorphic-granular texture.  Originally mapped as part of Merrill Pass pluton, separated because of higher color index and presence of hornblende.
K-Ar discordant biotite (31.9 Ma) and hornblende (36.3 Ma), same sample.
South Fork stocks
Several small stocks consisting of fine- to medium-grained, seriate to subporphyritic, hypidiomorphic-granular biotite granite.
Goldpan Peak Gabbro
Small intrusion of fine- to medium-grained to fine- to coarse-grained, seriate, hypidiomorphic granular gabbro.  Intruded by and completely surrounded by Merrill Pass pluton.
Chilligan Porphyry
Chiefly fine- to coarse-grained, biotite- or biotite-hornblende granite or granodiorite, containing alkali feldspar phenocrysts.
K-Ar biotite (60.6 Ma) and hornblende (61.3 Ma), concordant
Tgl
A-2 Gabbro
Dark-colored hornblende and pyroxene-hornblende fine- to medium-grained gabbro.  Two varieties, one foliated (cumulate?) and a non-foliated variety.
40/39 biotite 61.4 Ma
Tse
Unnamed pluton
Medium- to coarse-grained, seriate, hypidiomorphic granular quartz diorite, granodiorite, and granite.
K-Ar biotite 57.5 Ma
TKtp
Tex Peak Mafic intrusion
Fine-grained, eqigranular, or fine- to medium-grained seriate gabbro.
Mesozoic or Paleozoic (Late Triassic?)
Small greenstone body consisting of dark greenish-black, massive, fine-grained equigranular greenstone.  May correlate with Chilikadrotna Greenstone, which has yielded Late Triassic fossils from interbedded limestone.
TKig
Igitna granodiorite
Ki
Unnamed stocks
Fine- medium-grained, seriate to porphyritic quartz monzodiorite.
K-Ar hornblende 79.1 Ma
Snowcap Central
Fine- to medium-grained, seriate, biotite-hornblende granite to granodiorite.
K-Ar biotite (33.5 Ma) and hornblended (35.2 Ma), concordant
Snowcap East pluton
Pluton ranging from gabbro to granite incomposition, with the more mafic compositions tending to be in the southern part of the exposure.
K-Ar biotite 41.5 and 50.1 Ma, thought reset; 40/39 biotite 64.8 Ma
Th
Hartman Plutons
Series of 4 elongate plutons, individually ranging from quartz monzonite and quartz monzodiorite to granite.  In general are fine- to medium-grained seriate intrusions, chiefly granodiorite.
K-Ar biotite 64.1 Ma and 40/39 biotite 65.1 Ma
Jimmy Lake stock
Leucocratic biotite granite, part of McKinley sequence?
40/39 biotite 65.0 Ma
Tme
Mount Estelle pluton
Two phases, slightly older and finer grained northern pluton consisting of medium-grained, hypidiomorphic-granular biotite- and hornblende-bearing granodiorite containing tourmaline as a characteristic accessory mineral.  It is largely esposed in the Tyo
K-Ar biotite and hornblende ranging from 62.0 to 64.2 Ma
TKmg
Mount Estelle Gabbro
Very fine- to fine-grained, sub-equiganular gabbro.
Sled Pass pluton
Elongate  fine- to coarse-grained, seriate pluton consisting chiefly of monzonite and monzodiorite.  Locally well-developed cataclastic foliation.
K-Ar hornblende 76.0 Ma and 40/39 biotite 70.1 Ma and hornblende 73.5 to 75.6 Ma
Mount Rich pluton
Fine- to medium-grained, seriate granodiorite to tonalite.  Presumably intrudes stock of McKinley sequence granite.  Contains subordinate phase is fine- to medium-grained granite.
40/39 biotite 38.6 Ma
Tcpi
Crowded Porphyry
Porphyritic hypabyssal intrusive rock containing 40-50 percent phenocrysts.  Phenocrysts are cheifly plagioclase feldspar and subordinate biotite and quartz.  Aphanitic silicieous groundmass
Johnson Creek pluton
Chiefly fine- to medium-grained seriate to subporphyritic quartz monzodiorite; less common is a porphyritic quartz monzonite phase.  Here inclides? Camp pluton
Tcc
Crystal Creek pluton
Large pluton of texturally variable, biotite +/- hornblende granite.
K-Ar biotite 60.0 to 62.0 Ma and hornblende 57.5 to 59.9 Ma.  K-Ar biotite of 52.6 thought reset
TKkm
Unnamed quartz monzonite pluton
Fine- to medium-grained seriate quartz monzonite.
Tsr
Stony River granodiorite
Fine- to medium-grained, seriate, hypidiomorphic granular granodiorite to quartz monzodiorite.
40/39 biotite 35.6 and 35.9 Ma
Swift River granodiorite
earliest Tertiary or Cretaceous?
Fine- to coarse-grained, seriate, hypidiomorphic granular granodiorite.  Outcrop area surrounded by Tired Pup pluton, thought to be older that Tired Pup.  Is this body mapped separately?
TKqc
Quartz Crystal pluton
Fine- to medium-grained, seriate, peralkaline granite to alkali feldspar granite.
Tv3
Seabee volcanic rocks
Predominantly crystal and crystal-lithic ash-flow tuff and lesser interbedded lava flows and local volcaniclastic sedimentary rocks.
40/39 biotite 36.5 and 41.0 Ma; 40/39 sanidene 37.6 Ma
Tv5
A-2 volcanic rocks
Chiefly crystal-lithic tuff and lesser volcaniclastic rocks, lava flows, and lahar/debris flows
Tv4
Snowcap volcanic rocks
Chiefly crystal-lithic ash-flow tuff and lesser interbedded lava flows and local volcaniclastic sedimentary rocks.
40/39 hornblende 33.6 Ma
Tv1
North volcanic center
Chiefly crystal-rich ash-flow tuff and lesser lithic-crystal ash-flow tuff and lava flows.  Two lahar deposits have been included in unit as well as a small hypabyssal porphyritic intrusion.  Lithic fragments in tuff are graywacke and argillite derived f
Tv2
Styx River Volcanics
Chiefly crystal-lithic ash-flow tuff and subordinate lava flows and local volcaniclastic rocks south of Jimmy Lake Pass.  Lithic fragments in tuff are chiefly volcanic and sedimentary rock fragments.  Sedimentary rock fragments are graywacke and siltston
JKs
Kahiltna terrane
Graywacke and argillite
MzPzs
Sandstone and graywacke
Unit supposed to continue into Lake Clark quadrangle, however no similar unit described in Lake Clark.  Unit assigned to Kakhonak Complex by default
TKiu
Small stocks scattered throughout eastern part of Lime Hills quadrangle.  Composition varies from biotite granite to hornblende-pyroxene quartz diorite.  Texture varies from fine-grained equigranular to fine- to coarse-grained seriate.
Sedimentary rocks (limey)
Sedimentary rocks. Undifferentiated shale, siltstone, argillite, and limestone.  Fossils, chiefly grapotlites, collected from these rocks are Late Cambrian(?), Ordovician, Silurian, and Devonian in age.  Tentatively correlated with Dilinger sequence of s
TKgs
Gneiss, possibly Mesozoic (Mzg)?
Tmpb
Merrill Pass breccia
Undifferentiated Quaternary surficial deposits
Moraine?
Qao
Outwash?
Rock glaciers?
Assigned to Quat, undivided by default
Lacustrine deposits?
Ttp
Tired Pup pluton
Large granite pluton, part of McKinley sequence.  Chiefly medium- to coarse-grained hypidiomorphic granular biotite- or biotte-hornblende granite.
K-Ar biotite ranging from 40.1 to 59.2 Ma, most credence given to 56.7 to 59.2 Ma ages.
Tnep
Northeast Prong, Tired Pup pluton
Large fine- to coarse-grained seriate, biotite or biotite-amphibole granite pluton.
K-Ar biotite ranging from 25.4 to 26.7 Ma
Ttp1
Tired Pup leucogranite
Fine- to nearly coarse-grained seriate biotite granite.  Gradational contact with main phase of Tired Pup pluton.
TKpg
Sled Pass Gabbro
Small dark-colored , fine- to medium-grained, seriate, hypidiomorphic-granular gabbro intrusion.  Uncertain relationship with Tired Pup pluton
Tiu
Unnamed granitic stocks
Fine- to medium-grained, seriate biotite-hornblende granite intruding 61 Ma gabbro.
Tlikakila pluton
Small pluton having two phases, quartz diorite and granodiorite.  Quartz diorite is fine- to medium-grained, seriate.  Granodiorite is fine- to medium-grained, subequigranular.
K-Ar biotite 44.6 Ma
Tms
Unnamed McKinley sequence intrusions
Leucocratic biotite granite stocks and dike swarms
Necons River pluton
Large multiphase pluton consisting of medium- to coarse-grained, seriate, hypidiomorphic granular granite to granodiorite and lesser gabbro.
40/39 biotite 35.6 Ma
Tgdn
Unnamed plutons
Gabbro to granite multi-phase bodies
K-Ar biotite on granite 64.0 Ma
Tus
Unnamed stock
Small hypabyssal stock consisting of a silicic(?), biotite and hornblende-bearing porphyry.
Bedrock, unknown
Unknown bedrock units
MM002
Mount McKinley
Qrf
Recent flood-plain deposits
Qca
Colluvium and older alluvium
Colluvium and other alluvium
Qsm
Superglacial moraine
Recent moraine
Qom
Older moraine
Qw
Tn?
Cantwell Formation, sedimentary rocks subunit
Felsic subvolcanic intrusive rocks
Mafic subvolcanic intrusive rocks
Tvg
Mount Galen Volcanics
See Gilbert, W.G., 1979, A geologic guide to Mount McKinley National Park:  Alaska Natural History Association.
Age of 38 Ma reported
Tvb
Tertiary granitic rocks
McGonagall pluton
Eielson pluton
Wyoming Hills pluton
Biotite and hornblende granodiorite, Foraker pluton
Biotite and biotite-muscovite granite, McKinley sequence, McKinley pluton
Biotite and biotite-muscovite granite, McKinley sequence, Ruth pluton
Felsic to intermediate volcanic rocks
Granitic rocks of Tertiary and (or) Cretaceous age
Tertiary and (or) Cretaceous
gr
Granitic rocks of uncertain composition and age
Unknown, probable Tertiary or Cretaceous
Granitic rocks of uncertian composition and age
Flyschlike rocks
Calcareous rocks
Trn?
Trps
Jurassic and Triassic
Limestone and basalt sequence
Devonian and Ordovician
Mississippian and Devonian
Spruce Creek sequence
Spruce Creek sequence of Kantishna Hills from Bundtzen thesis
Pzc?
DSu
Sedimentary rocks, undifferentiated
Undifferentiated sedimentary rocks, same as unit Dmf, Dmb, Dms of Csejtey (1992, HE002)
DSu?
Pzsc?
DOs?
DOls
Sedimentary sequence, limestone interbeds
Sedimentary sequence, massive limestone interbeds
DSb
Pelitic and quartzose schist sequence
PzpCp?
Sheared grit, quartzite, and quartz-mica schist
Dike swarm
Two areas of dike swarms consisting of felsic and mafic (southern area) or felsic (northern area) dikes.
TY002
Tyonek
Includes alluvium, talus, rock glaciers, and various morainal deposits.  Bedrock outcrops are present in ravines and along cut banks of rivers
TY003
Qv
Quaternary (with mixed Tertiary?)
Lava, breccia, and associated pyroclastics.  May include Tertiary volcanic rocks
Tertiary (with mixed Quaternary?)
Basaltic lava, tuff, and breccia.  May include Quaternary volcanic rocks
QTv
Tkb
Beluga Formation
Sandstone, siltstone, and coal
Kenai Group
Sandstone, conglomerate, clay, and coal
TY004
Miocene and Oligocene
Sanstone, siltstone, coal, and conglomerate
West Foreland Formation
Conglomerate, sandstone, and siltstone; mostly tuffaceous
Undifferentiated volcanic mafic and felsic flows, tuff flow breccias
Tsxr
Styx River Batholith
Biotite granite and quartz monzonite.  Weathers light brown to dark yellowish orange.  Intrudes the Mount Estelle intrusive and granodiorite of the Nagshlamina River
Late Paleocene to Early Eocene
Granite, granodiorite, diorite, and minor quartz monzonite
55 and 61 Ma
Granite, quartz monzonite, and syenite
K-Ar data:  Five dates from Biotite: 59.0+2.4 m.y.; 58.3+1.7 m.y.; 56.5+1.6 m.y.; 57.0+1.7 m.y.; and 58.2 m.y.  One date from Hornblende: 58.7+1.8 m.y.
Chilligan River Pluton
Medium-grained porphyritic biotite-hornblende quartz monzonite and granodiorite.  Phenocrysts of K-feldspar
Granodioritic rocks
Granodiorite and quartz diorite
K-Ar data:  One date from Biotite: 60.8+1.8 m.y.  One date from Hornblende: 61.9+1.8 m.y.
Mount Estelle Pluton
Medium grained hornblende-biotite granodiorite and quartz monzonite
Granodiorite of the Nagishlamina River
Medium-grained hornblende-biotite granodiorite
TKft
Felsic Tuff
Early Tertiary or Cretaceous
Crystaline tuff and lapilli tuff
Unassigned intrusive rock
Undifferentiated felsic and mafic intrusive rocks
TKi1
Unassigned intrusive rocks
Chiefly granite and quartz monzonite.  Rocks east of Skwenta River and south of Merrill Pass may be equivalent to Styx River batholith
TKgd
Granodiorite, quartz diorite, and diorite
K-Ar data:  Three dates from Biotite: 62.9+1.8 m.y.; 70.9 m.y.; 62.6+1.8 m.y.  Four dates from Hornblende: 72.0 m.y.; 68.6+2.1 m.y.; 72.1 m.y.; 64.8+1.9 m.y.
Early and Late Cretaceous
Sandstone, siltstone, conglomerate, cherty argillite, and limestone
Cretaceous basalt
Dark green and gray aphanitic basalt with local pillow forms
Quartz monzonite and syenite
K-Ar data:  One date from Hornblende: 107+3.2 m.y.
Cretaceous (?)
Feldspathic wacke with interbeds of siltstone.  Locally calcareous.  Weathers reddish brown
KJu
Metasedimentary rocks (undivided)
Cretaceous and (or) Jurassic
Weakly metamorphosed slate and graywacke; locally includes volcanic and intrusive rocks, undivided
Undifferentiated metasedimentary rocks.  Slate, graywacke, siltstone, argillite and phyllite, andalusite schist near contact with Hartman River intrusives.  Medium to dark gray.  Locally red weathering feldspathic wacke (Kw)
Volcanic breccia, tuff, agglomerate, and aphanitic lava flows; as mapped, locally includes Kamishak Formation in Ilianna Quad
Metavolcanic and Metasedimentary rocks
Predominantly metavolcanic rocks of pre-Cretaceous age.  Chiefly metabasalts and metaandesites.  May be equivalent to the Talkeetna Formation.  Locally includes subordinate metasedimentary rocks
Trk
Kamishak Formation
Limestone, grey to black chert, and porcellanite
Limestone and fine-grained tuff
Trlst
Chert and some greenstone
Chiefly sphene-bearing quartz diorite and diorite
Unassigned mafic rocks
Chiefly diorite and olivine and/or hornblende gabbro.  Occurs as inclusions in Tertiary intrusive rocks.  Locally may be metamorphosed equivalent of unit Mzi
Mzs
Predominently metasedimentary rocks of pre-Cretaceous age.  Locally includes subordinate metavolcanic rocks.  Locally includes metasedimentary rocks (Km) of Cretaceous age
Undifferentiated metavolcanic and metasedimentary rocks of pre-Cretaceous age.  Locally may include metasedimentary rocks (Km) of Cretaceous age
Surficial materials, undivided
Includes stream alluvium, colluvial deposits, terrace gravel, eolian deposits, and glacial deposits
TN003
Sedimentary rocks, undivided
Tertiary, Eocene
Volcanic rocks, undivided
Paleocene to Eocene
Bimodal assemblage of rhyolite and banded rhyolite flow rocks, rhyolitic breccia, tuffaceous sedimentary rocks, and amygdaloidal basalt flow rocks.
Late Cretaceous to Early Tertiary
See unit TKV, TN002
Granitic rocks, undivided
Light- to vey light-gray quartz monzonite, may range to granite.
Kwc
Wilber Creek unit of Weber and others (1992)
Interlayered siltstone, shale, snadstone, and conglomerate.  Impure graywacke rich in volcanic detritus is locally characteristic and probably correlates with the Kathul Graywacke of the Charley River quadrangle.
Ray Mountains pluton and part of another large pluton at north central edge of quadrangle.  Quartz monzonite, granite, monzonite, and possibly granodiorite.
Part of Melozitna pluton.  Quartz monzonite, granite, monzonite, and possibly granodiorite.
Granitic rocks of uncertain composition, texture, and age; may be equivalent to KG unit of Melozitna quadrangle (MZ002)
Wolverine quartzite unit of Weber and others (1992), undivided
Early Cretaceous and or Jurassic
Light-gray quartzite and dark-gray, cleaved, subphyllitic argillite and shale, part of unit KJcs of Chapman and others.
KJwq
Wolverine quartzite unit of Weber and others (1992), quartzite
Light-gray  to tan, white weathering, massive-bedded, moderately well-sorted, subrounded fine- to medium-grained quartzarenite.  Correlative with Keenan Quartzite of Charley River quadrangle according to Dover but I wonder if this is the wrong unit and i
KJwa
Wolverine quartzite unit of Weber and others (1992), sandstone and shale
Dominantly gray o black argillaceous rocks containing interbeds of Wolverine-type quartzarenite.
Jsc
Serpentinite and or carbonatite
Serpentinite, diabase-gabbro and some metadiorite and magnetite-rich
JMr
Rampart Group and associated mafic intrusive rocks, undivided
Mississippian to Jurassic
JMbc
Basalt and chert
Mississippian to Jurassic?
Dominantly basalt, altered basalt, and subordinate diabase and a low-grade cataclastic assemblage of generally dark gray chert and silicieous argillite.  Also subordinate volcaniclastic rocks and minor Mississippian limestone
Paleozoic?
Metamorphosed mafic igneous rocks, ranging from metagabbro and metadiabase to greenstone, amphibolite, and garnet amphibolite. (Shown on source map compilation as unit Pzg)
Pzrmi
JMu
Mafic and ultramafic rocks, undivided
Massive and layered gabbro, leucogabbro, harzburgite, garnet amphibolite, serpentinized peridotite, and dunite
Schist of Ruby and Garnet Creeks area
Polymetamorphic staurolite-garnet-schist containing subordinate quartzite, and hornblede amphibolite
Metalimestone and marble
Permian to Triassic
Dominantly dark-gray, typically phyllitic, silicieous to carbonaceous argillite and shale, having subordinate but characteristic clast-supported chert-rich conglomerate, greenish-gray chert, tuffaceous volcaniclastic rocks, yellowish- to reddish-brown hi
Ml
Gray, bioclastic limestone, found in structurally isolated thrust slice  Not on OFR98-133
Dao
Augen orthogneiss
Augen most commonly of white potassium feldspar, range in size from 1 to 10 cm long, most about 4 cm long.  Biotite is scarce to abundant.  Foliation layers containing biotite bend around augen.
MDrao
Mq
Globe quartzite
Vitreous quartzite associated with gabbro sills and dikes.  Light-gray quartzite.  Massive or thinly interbedded quartzite and medium- to dark-gray slate, phyllite, and minor laminated claystone.  Age from date of Trm intrusive and lithologic and stratig
pCa
Amy Creek unit of Weber and others (1992)
Late Proterozoic? to early Cambrian?, Devonian?
White, massive, locally laminated, unfossiliferous cherty dolostone characterized by replacement silica boxwork locally and gray limestone at top and bottom of section.  Possible other correlations suggest this unit is equivalent to unit Dld of this quad
Dld
Latest Devonian (Famennian)
Light- to medium-gray or tan marker units of sandy, platy limestone and massive-bedded silicified limestone and dolostone having extensive locally developed boxwork silica.  Not on OFR98-133
Platy limestone and a limestone bed thought to be part of the section contains sparse conodonts of Famennian age.
Dlr
Limestone of Raven Ridge
Gray micritic limestone and brecciated limestone.
Undescribed megafossils
Pzmr
Distinctive marker bed of coarsely recrystallized marble within Pzsr unit
Fossil Creek Volcanic unit of Weber and others (1992)
Agglomeratic mafic volcanic rocks, volcaniclastic rocks, and assoiciated argillaceous sedimentary rocks
Livengood Dome Chert?
Heterogeneous, low-grade, blastomylonitic assemblage of silicieous to cherty argillite, recrystallized chert, intermediate to mafic volcaniclastic rocks and greenstone, graywacke, grit, and oolitic limestone.  Resembles lower grade parts of unit Pzs in t
Pzll
Distinctive marker bed of lime mudstone, locally characterized by coated ooids; is part of Livengood Dome Chert
Oldl
pCw
Wickersham unit of Weberr and others (1992), undivided
Cambrian and or Late Proterozoic
Poorly sorted quartzite and grit, having abundant quartz and plagioclase clasts in a quartzofeldspathic-wacke matrix.
Low to  moderately high-grade, blastomylonitic, polymetamorphic assemblage of pelitic to quartzitic schist containing subordinate layers of quartzo-feldspathic schist, calc-schist, calc-sliciate gneiss, amphibolitic schist, quartzite, marble, and metacon
Relatively pure quartzite units locally mappable and typically associated with mafic rocks (unit Pzm) and metalimestone and marble (unit Pzl).  (Shown on source map compilation as uncolored Pzqs)
PzpCqg?
Quartzofeldspathic orthogneiss
Late Proterozoic? and or Paleozoic?
Quartzofeldspathic orthogneiss, located only on west side of Ray Mountains pluton.
Olc
Separate from Pzlc which was described as:  Heterogeneous, low-grade, blastomylonitic assemblage of silicieous to cherty argillite, recrystallized chert, intermediate to mafic volcaniclastic rocks and greenstone, graywacke, grit, and oolitic limestone.
TKhf
Hornfels and skarn
Cretaceous and Paleocene
Brown to gray, massive to locally porphyroblastic, garnet-chlorite-biotite hornfels derived from carbonate and clastic rocks.  Assigned to unit of provenence
MG002
McGrath
Active Glaciers
Pleistocene and Holocene
Occupy cirques with base level above 4,800 to 6,100 ft elevation
Stream Alluvium, undifferentiated
Fluvial silt, sand, and gravel deposited by streams in floodplains, fans, and meandering to distributary stream channel deposits
Terrace Alluvium
Wisconsin to early Holocene
Moderately to well sorted, well stratified, gray to tan (oxidized), fluvial silt, sand, and gravel of varying ages deposited on former floodplains that now lie above or beyond the normal depositional regime of Holocene streams.
Alluvial-fan deposits
Late Wisconsin to Holocene
Poorly to moderately well sorted, gray to tan (oxidized), fluvial silt, sand, and gravel deposited where first- and second-order tributaries join third- and fourth-order streams
Colluvial-alluvial deposits
Mixed or alternating, poorly to moderately sorted, silt, sand, gravel, and diamicton of colluvial and alluvial origins
Qct
Angular, unsorted debris derived from frost riving of bedrock followed by rapid gravity transport on steep slopes, cirque headwalls, steep gullies, and avalanche chutes
Qcl
Chaotically deformed colluvium derived from relatively sudden mass movement of bedrock or surficial deposits along a plane of failure.  Hummocky and usually frozen
Eolian deposits
Well-sorted sand and silt transported and deposited by wind.  Usually frozen
Silt and Peat
Poorly stratified, black to brown, organic rich, alluvial, eluvial, lacustrine, and bog silt and peat.  Usually frozen, except near stream cuts
Qdic
Ice-contact deposits
Wisconsin and early Holocene
Stratified gravel, sand, and flowtill deposited on, against, or under stagnant masses of glacial ice by meltwater streams
Qdt
Late Wisconsin and Holocene
Unsorted to poorly sorted clay, silt, sand, and gravel deposited by glacial ice
Qrg
Rock Glaciers and Rock-Glacier deposits
Unsorted, angular, frost-shattered cobbles and boulders, commonly containing considerable intersticial ice.  Usually frozen.
Qdtf
Till of Farewell Glaciation
Wisconsin
Unsorted to poorly sorted clay, silt, gravel, and boulders deposited by glacial ice as ground, terminal, and lateral moraines.  Mostly the result of Farewell I and Farewell II glaciations
Outwash
Stratified drift consisting of coarse subrounded gravel that contains sand and silt lenses deposited by sideglacial and proglacial meltwater streams.  Usually frozen
Qdot
Outwash Terrace
Early to middle Pleistocene
Remnant of former outwash fan or plain deposit (Qof)
Qdts
Till of Selatna GLaciation
Unsorted to poorly sorted clay, silt, and gravel deposited by glacial ice in ground moraines
Qdtlm
Till of Lone Mountain Glaciation
Early or middle (?) Pleistocene
Isolated patches of unsorted to poorly sorted silt, gravel, and highly eroded erratics deposited by glacial ice
Qof
Outwash-fan deposits
Middle Pleistocene to early Wisconsin
Glaciofluvial sand and silt derived from streams originating near ancestral glacial margins.  Usually frozen
Qdtplm
Till of Pre-Lone Mountain Glaciation
Pliocene and Pleistocene
Isolated patches of unconsolidated to weakly cemented, diamicton largely recemented by calcite-forming tillite.  May correlate with deformed till and outwash (QTg)
Consolidated Till and Outwash
Weakly to well cemented diamicton, interbedded with crudely stratified outwash, with local and exotic lithologies
Paleocene to Oligocene
Tcf
Felsite Conglomerate
Oligocene and Miocene
Thick-bedded, poorly indurated, orange-weathered, light brown granule, cobble conglomerate with clasts of felsic igneous rocks.
Tcg
Coal-bearing sandstone, shale, and conglomerate
Late Paleocene (?) to Oligocene
Thin- to thick-bedded, poorly to moderately indurated, buff-weathered, gray-brown, granule to cobble conglomerate, minor sandstone, and interbedded dark gray carbonaceous shale and coal.  Correlated with Ts
Sandstone and shale
pre-Middle Eocene
Thin- to thick-bedded, moderately indurated, red-brown weathered, buff, medium-grained, lithoquartzose sandstone interbedded with poorly indurated, laminated, fissile, carbonaceous shale and fine sandstone.  Correlated with Tcg
Tcl
Limestone conglomerate
Thick- to thin-bedded, moderately indurated, green-gray granule conglomerate exposed in fault sliver near Khuchaynik Creek.  Although it is compositionally distinct, it crops out near Ts and Tcg, and is correlated with them
Volcaniclastic sandstone and lacustrine silt
Brown to gray, medium- to fine-grained volcaniclastic sandstone that has a distinctive 50 ft thick section of flora-rich paleosols and finely laminated, varved shales of probable lacustrine origin aqsscoiated with the Ship Creek, Windy Fork, and Terra Co
Metasequoia cuneata and Glyptostrobus europaeus (plant fossils)
Andesite flows and lapilli tuff
Dark-gray to green-gray andesite flows and locally banded (red, green, purple, bleached) lapilli tuff.  Groundmass is aphanitic to fine-grained of Ship Creek, Windy Fork, and Terra Cotta Volcanic Fields
Whole-rock K/Ar age of 37.1 Ma from Windy Fork volcanic field
Tvvd
Vent facies dacite
Eocene and Oligocene
Very distinctive, light gray, distinctively tan weathering, hornblende and potassium-feldspar-rich, propylitically altered dacite containing very abundant angular clasts of sedimentary rocks of Ship Creek, Windy Fork, and Terra Cotta Volcanic Fields;
Tvlr
Lapilli rhyodacite
Light- to medium-gray, porphyro-aphanitic, potassium-feldspar-rich rhyodacite flows containing conspicuous layers of purple, green, and red lapilli tuff beds.  Ship Creek, Windy Fork, and Terra Cotta Volcanic Fields
Tvgt
Green tuff
Distinctly mid- to dark-green, fine to medium grained ash flow (?) tuff containing very minor blocks of darker green, altered agglomerate composed of rounded clasts.  Marker bed for Terra Cotta volcanic field.  Ship Creek, Windy Fork, and Terra Cotta Vol
Tvl
Lahar deposits
Medium- to dark-green-gray, very coarse grained lahar deposit.  Ship Creek, Windy Fork, and Terra Cotta Volcanic Fields
Tvf
Felsic tuff and flows
Bleached to light-gray, locally banded, hypocrystalline rhyolite tuff and flows.  Ship Creek, Windy Fork, and Terra Cotta Volcanic Fields
Tvm
Basalt and basaltic andesite
Dark gray to maroon, locally porphyritic, columnar jointed, olivine bearing, augite basalt and basaltic andesite flows.  Ship Creek, Windy Fork, and Terra Cotta Volcanic Fields;
Four K/Ar ages ranging from 41.3 Ma to 48.9 Ma from the Ship Creek volcanic field
Tid
Undifferentiated sills and dikes
Eocene to Miocene
Undifferentiated sills and dikes of mafic and felsic composition
Tia
Andesite-trachyandesite sills and dikes
Green-gray, fine-grained, hypidiomorphic-granular, porphyritic andesite dikes less than 65 ft thick.  Local variety-granodiorite
Five K/Ar ages from 20.9 to 39.3 Ma
Felsic sills and dikes
Felsic (light pinkish tan to white), aphanitic- to fne-grained, dikes and sills up to 16 ft thick
Mafic sills and dikes
Mafic (dark brown), pandiomorphic-granular, sills and dikes up to 34 ft thick.  Locally porphyritic basalt, gabbro, and diabase
K/Ar mineral ages ranging from 45.5 to 55.0 Ma
Tvld
Lapilli tuff
Light gray to bleached white with yellowish staining, locally banded (purple, white), lapilli dacite and tuff of Ship Creek, Windy Fork, and Terra Cotta Volcanic Fields
Tvd
Massive dacite
Light- to medium-gray, porphyro-aphanitic, hornblende-bearing massive dacite of Terra Cotta volcanic field of Ship Creek, Windy Fork, and Terra Cotta Volcanic Fields
Whole-rock Ar/Ar age of 31.3 from Terra Cotta volcanic field
Tvt
Intermediate to felsic air-fall tuff
Composite unit of light- to medium-green-gray, well laminated medium to very coarse grained, crystal-rich, air-fall tuff of Ship Creek, Windy Fork, and Terra Cotta Volcanic Fields
Petrified wood, dicotyledon, and Metasequoia
Tvab
Andesite breccia
Medium-gray, purple-hued weathering, porphyritic, pyroxene andesite containing distinctive zones of pyroclastic breccia consisting of in situ andesite fragments.  Groundmass is aphanitic to interstitcial.  Ship Creek, Windy Fork, and Terra Cotta Volcanic
Ar/Ar age of 41.1 Ma from hornblende of Terra Cotta volcanic field
Twg
Windy Fork granite
White to pink and locally blue-gray, medium- to coarse-grained, peralkaline arfvedsonite granite of Windy Fork pluton
K/Ar ages of 23.4 Ma from pyroxene, 30.1 Ma from biotite, and 29.0 Ma from hornblende
Hartman pluton granodiorite
Medium- to coarse-grained, equigranular, hornblende-biotite granodiorite with a strong hornfels aureole.  (Not equivalent in age to Hartman plutons of Lime Hilles quadrangle.)
K/Ar age of 37.9 Ma from biotite
Quartz monzonite, monzonite breccia, and quartz porphyry
Composite unit of light gray, fine- to medium-grained hypidiomorphic to equigranular, biotite quartz monzonite, aegirine-rich monzonite, and altered biotite quartz porphyry
Nine K/Ar ages range from 51.1 to 61.8 Ma
Tgdp
South Fork granite
Light gray, pink, medium- to coarse-grained, equigranular, biotite (muscovite) granite
K/Ar age of 58.8 Ma from biotite
Tgqm
Middle Fork Plutonic Complex; granite, quartz monzonite, and monzodiorite
Fine- to medium-grained, biotite- and hornblende-bearing plutonic rocks with variable quartz contents and feldspar ratios
Three K/Ar mineral ages of 56.1, 56.6, and 57.2 Ma from quartz monzonite.  Two K/Ar ages of 57.7 and 55.6 Ma
Tgsy
Middle Fork Plutonic Complex; granite to quartz syenite
Fine- to medium-grained, granite to quartz syenite
Tsy
Middle Fork Plutonic Complex; syenite
Green-gray, white-gray weathering, medium- to coarse-grained, olivine-clinopyroxene syenite.  Locally iron stained
TKqm
Mount Estelle granodiorite
Fresh, medium-gray, medium-grained, equigranular, hornblende-biotite granodiorite.
Ar/Ar age of 79.0 Ma from biotite
Tgb
Middle Fork Plutonic Complex; alkali gabbro
Dark green-brown, fine- to medium-grained, biotite-olivine-pyroxene gabbro
TKvt
Air-fall tuff of intermediate composition
Light- to medium-green-gray, well-laminated, crystal tuff.  Veleska Lake Volcanic Field
'rich in undated plant fossils'
Gabbro-granodiorite
Heterogeneous dike swarms consisting of augite gabbro, hornblende granodiorite, and monzodiorite
K/Ar ages of 69.7 Ma from biotite and 79.0 Ma from hornblende
Rhyolite tuff
White- to light-gray, locally banded, hypocrystalline rhyolite.  Veleska Lake Volcanic Field
Dacite flows and dikes
Light- to medium-gray, aphanitic to porphyro-aphanitic, chloritized hornblende dacite flows.  Veleska Lake Volcanic Field
K/Ar age of 65.8 Ma
TKvm
Basalt andesite
Medium-gray-green, fine-grained, augite-rich basaltic andesite and minor andesite flow breccia.  Veleska Lake Volcanic Field
KJsh
Flyschoid sandstone and shale
Jurassic and Cretaceous
Medium- to very dark-gray, fine-grained, lithic sandstone, siltstone, and shale.  Kahiltna Terrane
Inoceramus murgalensis and Inoceramus peltiformis pochialaynen (Early Cretaceous)
Coarse sandstone and minor siltstone
Medium-gray to distinctly tan-weathered, lithic sandstone containing clasts of volcanic rocks, sandstone and shale, granitic rocks, quartz, and lime-rich sediments.  Flute clasts and ripple marks common.  Kahiltna Terrane
Early Cretaceous pelecypods
KJc
Pebble to boulder conglomerate and minor sandstone
Light-gray, tan weathered, pebble to boulder conglomerate.  Kahiltna Terrane
Inoceramus murgalensis (Early Cretaceous)
Buff-weathered, dark green-gray gabbro and diorite.  Unit may be equivalent to Jurassic-Cretaceous gabbro-diorite swarm that intrudes along a major suture separating the Pingston Terrane from the Yukon-Tanana terrane in Denali National Park
Slate and metasiltstone
Very thin-bedded, fissile, rusty-brown-weathered, black slate, metasiltstone, micaceous metasandstone, and rare silty limestone turbidite.  McKinley Terrane
Mesozoic radiolaria and megafossils from Talkeetna quad
lJs
Tatina River Volcanics; phosphatic shale and green volcaniclastic sandstone
Medium- to very-dark-gray, distinctly bleached bluish-white, phosphatic shale; green, medium grained, concretion-rich, volcaniclastic sandstone; and minor tan chert-cobble pebble conglomerate.  Farewell Composite Terrane
Entolium sp. and Eopecten (?) sp. of Jurassic age
Trls
Limestone and shale
Thin-bedded, medium gray quartzitic limestone; gray, silty limestone, and shale.  Basal beds mainly fine-grained, gray sandstone and siltstone and subordinate cherty limestone.  Pingston Terrane
Monotis sp. (Late Triassic) pelecypod
Tatina River Volcanics; shale, coarse volcaniclastic sandstone, and chert
Tan to greenish-gray, buff to orange weathered, pebble rich, immature conglomerate, coarse volcaniclastic sandstone, distinctly brown silty shale, and light gray, green, and black chert.  Farewell Composite Terrane
Monotis subcircularis and Halobia cf. fallax late-Early-to-early Late Norian of the Late Triassic
Trab
Tatina River Volcanics; pillow basalt and gabbro
Dark green-gray, massive, aphanitic to medium-grained, olivine-clinopyroxene rich, pillow basalt, olivine diabase and gabbro sills, and mafic agglomerate.  Locally well developed pillow structure.  Farewell Composite Terrane
Trum
Ultramafic to diorite sills
Dark green-gray, fine- to coarse-grained, ultramafic sills, olivine gabbro, and diorite, 50 to 66 ft thick
Gabbro and diorite sills and dikes
Brownish weathered, dark green-gray, very fine- to medium-grained phaneritic, locally micropegmatoidal, olivine, aegirine-augite, gabbro, diorite, and uncommonly alkali syenite
uPzs
Volcanogenic phyllite
Dark gray-green to distinctly maroon, pyrite-rich volcanogenic phyllite cut by thin quartz-carbonate veins.  Yukon-Tanana Terrane
PMpc
uPzc
Phyllitic chert and siliceous phyllite
Mississippian to Permian
White-weathered, gray-green, banded phyllitic ribbon chert.  Yukon-Tanana Terrane
Pennsylvanian through Permian radiolaria; Mississippian through Permian Radiolaria and conodonts
PDs
Sheep Creek Formation; sublithic sandstone, limestone-chert conglomerate, and minor limestone
Middle Devonian to Permian
Medium-gray, distinctly brown-red weathered, medium- to coarse-grained, sublithic sandstone and pebble conglomerate that contains clasts of limestone, chert, lithic fragments, volcanic clasts, and polycrystalline quartz.  Limestone-chert conglomerate nea
Fusilinids (Late Pennsylvanian to Permian), Palmatolepis sp. and Polygnathus sp. conodonts (Frasnian(Late Devonian)), Dendrostrella sp. cf. D. trigemme (Late Eifelian and Givetian (Middle Devonian)),
mSl
Terra Cotta Mountains Sandstone; argillaceous graptolitic limestone
Medium- to dark-gray and brown weathered limestone containing graptolite-bearing silty sandstone intervals.  Generally equivalent to Middle Limestone member of Churkin and Carter (1996).  Dillinger Subterrane
Pristiograptus dubious, Monograptus cf. M. ludensis, and Monograptus digitatus (Wenlockian stage of the Silurian) Also orthoconic nautiloid cephalopods, cardiolid bivalves, and ribbed atrypacean brachiopods of probably Silurian age
Stc
lSl
Post River Sandstone; boundary limestone
Early Silurian
Thin, dark gray, fetid, laminated limestone with thin silty sand layers, and thin interbeds of black cherty argillite.  Dillinger Subterrane
Cryptograptus centrifugus of C. centifugus zone, earliest Wenlockian stage, late Early Silurian
uSsl
Terra Cotta Mountains Sandstone; thin-bedded calcareous sandstone, graptolitic shale, and silty limestone
Thin-bedded, gray to tan, micaceous sandstone, silty limestone, and dark gray graptolitic shale.  Local flute clasts and ripple marks.  Probably equivalent of Upper Limestone member of Churkin and Carter (1996).  Dillinger subterrane
Monograptus cf. M. pseudodubius, Lobograptus progenitor, and Pristiograptus cf. P. tumescens from the Neodiversograptus nilssoni zone, Ludlovian stage (Late Silurian)
mSvs
Terra Cotta Mountains Sandstone; phyllite, volcaniclastic sandstone and chert
Thin-bedded, complexly folded, maroon to green phyllite, medium-green, medium-grained volcaniclastic sandstone, and green-gray chert.  Dillinger Subterrane
mSs
Terra Cotta Mountains Sandstone; feldspathic-lithic sandstone, limey siltstone, and argillite
Medium olive gray to terra cotta, medium-to coarse-grained, thin-bedded to massive, calcareous lithic sandstone, and siltstone containing local gray shale intervals and minor pebble conglomerate beds.  Sandstones have well developed oscillation ripple ma
Monograptus aff. M. Priodon and Cryptograptus lundgreni (middle to early Wenlockian stage of Silurian)
uDl
St. Johns Hill Formation; massive micritic limestone
Medium-gray, massive- to thck-bedded, micritic limestone that contains crypto-algal laminations, thin, black chert partings, and dolomitic nodules.  Identical in age and character of unit described by Reed and Nelson (1980) near base of Mystic subterrane
Rugose corals, brachiopods, and pelecypods (Frasnian (early Late Devoian))
St. Johns Hill Formation; limestone and minor siltstone
Brown to terra cotta, micaceous, slightly pyritic, thinly laminated mudstone, siltstone, limestone, and medium-grained lithic sandstone.  Tentatively correlative basal portion of PDs.  Farewell Composite Terrane
Barren Ridge Limestone; calcarenite, calcareous siltstone, and laminated limestone
Silurian and Devonian
Thin- to thick-bedded, buff to orange-weathered, light- to medium-gray, phyllitic calcarenite, thin-bedded orange to buff siltstone, and light-gray silty limestone.  Dillinger subterrane
Conodonts (Late Silurian to Late Devonian)
DSca
lDl
Sheep Creek Formation; massive algal limestone
Massive, thick-bedded, medium-gray limestone, rich in algal laminations and Amiphipora sp.  Farewell Composite Terrane
Ozarkodina sp. indet. or Kockelella sp. indet. (Middle Silurian-to-early Devonian)
lDd
Sheep Creek Formation; dolomite
Light gray, dolomitized, algal (?) limestone similar in appearance to lDl.  Thought to be correlative with lDl.  Farewell Composite Terrane
SOsh
Post River Sandstone; graptolitic shale, siltstone, and chert
Ordovician and Silurian
Medium- to dark-gray, fetid, fissile, isoclinally folded, carbonaceous shale, siltstone, and black bioturbated, silaceous siltstone and chert.  Local distinctive sulfurous plumes.  One of the most complete Ordivician-Lower Silurian graptolite successions
15 graptolite zones representing 5 of 6 Ordivician stages and most of the Landoverian stage of the Early Silurian
OCls
Lyman Hills Formation; silty limestone and shale
Cambrian and Ordovician
Rhythmically layered, thin-bedded, orange to buff, light gray when fresh, limestone, silty shale, and light olive shale.  Lime units have parallel and cross laminations.  Shale and siltstone have ripple-laminated structures with amplitudes of 5 to 70 cm.
Adelograptus graptolite zone of the Early Ordovician, Teridontis nakamurai of the Cordylodus lindstromi zone of the Late Cambrian-to-Early Ordovician
Metaquartzite and calcareous phyllite
Precambrian to Devonian
Light- to medium-gray, fine- to coarse-grained, metaquartzite, quartz-feldspar "grit", calcareous phyllite, and minor metachert.  Minchumina subterrane
Tids
Dike swarm and hornfels
Large linear zones of multiple dikes of variable composition and size that create extensive hornfels aureole and include fragments of layered country rocks
Surficial deposits, undifferentiated
GU002
Gulkana
Qco
Colluvial deposits, river bluff type
Conglomerate, fluvial deposits derived from Wrangell Lava and deposited on unit QTu, undifferentiated volcanic rocks and older, pre-Wrangell rocks
Late Pleistocene
Qds
Active cliff-head dune deposits
Qnf
Volcanic rocks-Nathlie Mountain eruptive center
Flows, breccias, and sedimentary rocks
Qcc
Volcanic rocks-Capital Volcano
Caldera lavas
Shield lavas
Qdf
Volcanic rocks-Drum Volcano
Cone building flows
Volcanic rocks-Sanford Volcano
Basalt, andesite, and dacite lava, undifferentiated
Qsdf
Sanford Debris flow deposits
Debris derived from collapse of a dome on Sanford Volcano.  Flow traveled a great distance down the Sanford Glacier/River valley to confluence with the Copper River
Volcanic avalanche deposits
Qva
Mineral spring and mud volcano deposits
Mineral Spring and mud volcano deposits
Qmsv
Qsh
Hyaloclastite
Cinder cones and associated flows
Qdc
Collapsed dome
Qi
Qsi
Shallow plutons
Qdd
Dacite domes
Qvd
Rhyolite domes
Qsr
Rhyodacite dome and flow
Qni
Dacite pluton
Qcr
Rhyolite dikes and laccoliths
Qcd
Radial dike swarm and plugs
QTu
Pleistocene and Pliocene (?)
Volcanic rocks, undifferentiated
Volcanic rocks-Wrangell Volcano
Holocene (?) and Pleistocene
Andesite flows and fragmental rocks
QTi
Qwd
Dacite flows
QTva
Cenezoic
Czab
Olivine basalt and andesite
Cenozoic
Andesite flows; Metamorphic Complex of Gulkana River
Tertiary (?)
Andesite flows
Granodiorite pluton
Granodiorite pluton, Wrangellia Terrane
Wrangellia Terrane
hbqd
Hornblende-biotite quartz diorite; Peninsular Terrane
Hornblende-biotite quartz diorite
hbqm
Hornblende-biotite quartz monzonite; Peninsular Terrane
Hornblende-biotite quartz monzonite
hbgd
Hornblende-biotite granodiorite; Peninsular Terrane
Hornblende-biotite granodiorite
Jtrd
Rhyodacite flows; Talkeetna Formation
Rhyodacite flows with minor sandstones and lesser dacite flows
Hornblende andesite flows; Talkeetna Formation
Hornblende andesite flows
Jts
Talkeetna Formation, sandstone
Sandstone with sparse volcaniclastics
shgb
Schistose hornblende gabbro; Metamorphic Complex of Gulkana River
Schistose hornblende gabbro
scgb
Schistose clinopyroxene gabbro; Metamorphic Complex of Gulkana River
Schistose clinopyroxene gabbro
sqm
Schistose quartz monzonite; Metamorphic Complex of Gulkana River
Schistose quartz monzonite
sqd
Schistose quartz diorite; Metamorphic Complex of Gulkana River
Schistose quartz diorite
sgd
Schistose granodiorite; Metamorphic Complex of Gulkana River
Schistose granodiorite
shd
Schistose hornblende diorite; Metamorphic Complex of Gulkana River
Schistose hornblende diorite
Amphibolite gneiss; Metamorphic Complex of Gulkana River
Amphibolite gneiss
Trg
Late Triassic (?)
Clinopyroxene-hornblende gabbro, and diabase and gabbronorite dikes
Clinopyroxene-hornblende stocks and plugs
qmfs
Quartz-muscovite-feldspar schist; Metamorphic Complex of Gulkana River
Late Paleozoic (?) or older
Quartz-muscovite-feldspar schist
mmp
Metamorphosed pelitic and calc-schist; Metamorphic Complex of Gulkana River
Metamorphosed pelitic and calc-schist
ds
Dadina schist
Coarse quartz-biotite schist, altered and cataclastic meta-andesite, over lain(?) by amphibolite schist, mica-schist, and minor meta-limestone.  Intruded by unmetamorphosed coarse-grained quartz diorite dikes.  Also includes sheared meta-gabbro.  Dadina
Metamorphosed hornblende andesite; Metamorphic Complex of Gulkana River
PPs
Middle and Late Pennsylvanian and Early Permian
Metamorphosed clinopyroxene basalt; Metamorphic Complex of Gulkana River
Metamorphosed clinopyroxene basalt
am
Amphibolite; Metamorphic Complex of Gulkana River
Amphibolite
PPf
Ahtell Pluton
Permian and Pennsylvanian
Fine-grained biotite granite
Pmgi
PPp
Porphyritic hornblende granodiorite
PPg
Biotite-hornblende granite and granodiorite
PPa
Diorite Complex
Altered diabase and gabbronorite
PPad
PPd
Diorite, granodiorite, and gabbronorite
Pt
Hornfels
Hornfels created from plutonic rocks described above : Km, Kmd, TKgr, TKgp, Tgd, Tqm, Tgr
MG003
Quaternary surficial deposits, undivided
Nonmarine sedimentary rocks
Eocene to Oligocene
Coal-bearing sandstone, shale and conglomerate
Fossil data summarized in Bundtzen
Tclg
Limestone-rich conglomerate
Granite of Cheeneetnuk River area
38 Ma
Quartz monzonite of Selatna Hills area
60 Ma
Granodiorite of the Selatna and Tatlawiksuk Hills area
61 and 62 Ma
Granite of Lone Mt. Complex
58.5 Ma and 65 Ma
Granite Porphyry
Kuskokwim Group; Deep Water (Turbidite-Fan) Facies
Coarse lithic sandstone and pebble conglomerate
Fine, medium, and coarse-grained lithic conglomerate
Calcareous medium to coarse-grained lithic sandstone and siltstone
Kus
Kuskokwim Group; Lithologies of Unknown Facies Assignment
Kuskokwim Group clastic rocks- undifferentiated
Shale and siltstone and very minor fine-grained sandstone
Kqs
Kuskokwim Group; Shallow Marine to Locally Nonmarine Shoreline Facies
Quartzose sublithic sandstone, siliceous shale, and siltstone; minor coal
Leaf hash and nonmarine to brackish water pelecypod fauna
Kqcs
Coarse grained sandstone and pebble-to-cobble conglomerate.  Quartz-rich sublithic to bleached white coarse facies of Kqs
Basaltic Andesite of Takotna and Candle Hills Volcanic-Plutonic Complex
Basaltic Andesite of Takotna and Candle Hills volcanic-Plutonic Complex
74 Ma
Kvmp
Porphyritic Basaltic Andesite of Candle Hills and Takotna Volcanic-Plutonic Complex
73 Ma
Olivine Monzonite of the Candle Hills Pluton
Olivine monzonite of the Candle Hills Pluton
70 Ma
Kmd
Monzonite and Monzodiorite of Takotna Pluton
Monzonite and monzodiorite of Takotna Pluton
72 Ma
Tholeiitic pillow basalt
Tholeiitic pillow basalt; Equivalent to Tatina River Volcanics of Buntzen and others, 1997 (Farewell Composite terrane, Mystic sub-terrane
Olivine Gabbro sills
Triassic to Tertiary
uPzac
Argillite and chert, equivalent to Sheep Creek Formation
Late Devonian to Permian
Argillite and chert; Equivalent to Sheep Creek Formation as defined by Buntzen and others, 1997 (Farewell Composite Terrane; Mystic Subterrane)
Pennsylvanian fossils
Sandstone and detrital limestone
Sandstone and detrital limestone (Farewell Composite Terrane; Mystic Subterrane)
Contains Upper Paleozoic fossils
Sheep Creek Formation, brown siltstone
Brown siltstone of Sheep Creek Formation (Farewell Composite Terrane; Mystic Subterrane)
Pennsylvanian fusilinids
Post River Formation, Graptolitic shale and chert
Silurian and Ordovician
Graptolitic shale and chert; Post River Formation of Churkin and Carter, 1996 and Buntzen and others, 1997 (Farewell Composite Terrane; Dillinger Subterrane)
Ssh
Mid-Silurian
Shale and siltstone; equivalent to Paradise Fork Formation of Dutro and Patton, 1982 (Farewell Composite Terrane; Nixon Fork Subterrane)
Terra Cotta Mountains sandstone; feldspathic-lithic sandstone
Middle Silurian
Feldspathic-lithic sandstone;  Terra Cotta sandstone of Churkin and Carter, 1996 and Buntzen and others, 1997 (Farewell Composite Terrane; Dillinger Subterrane)
Thick bedded dark gray limestone
Late Devonian (Frasnian)
Thick bedded dark gray limestone (Farewell Composite Terrane; Mystic Subterrane)
mDl
Cheeneetnuk limestone
Middle Devonian (Late Emsian to Givitian)
Cheeneetnuk limestone (Farewell Composite Terrane; Mystic Subterrane)
SDlw
Whirlwind Creek Formation (limestone and dolomite)
Middle Devonian (Late Emsian to Givitian (?))
Shallow water limestone and dolomite of Whirlwind Creek Formation as defined by Dutro and Patton, 1982 (Farewell Composite Terrane; Nixon Fork Subterrane)
Barren Ridge limestone; calcarenite, calcareous siltstone, and laminated limestone
Calcarenite, calcareous siltstone, and laminated limestone;  Barren Ridge limestone of Churkin and Carter, 1996 and Buntzen and others, 1997 (Farewell Composite Terrane; Dillinger Subterrane)
Dolomite
Early Devonian
Thick bedded, cream-colored dolomite (Farewell Composite Terrane; Nixon Fork Subterrane)
Gray limestone interbedded with dolomite
Gray limestone interbedded with lDd (Farewell Composite Terrane; Nixon Fork Subterrane)
Sla
Algal limestone
Algal limestone (boundstone) thick-bedded algal-rich stromatoporid-rich limestone (Farewell Composite Terrane; Nixon Fork Subterrane)
Stromatoporid
uOll
Laminated limestone
Laminated limestone; Probably equivalent to upper part of Telsitna Formation of Dutro and Patton, 1982 (Farewell Composite Terrane; Nixon Fork Subterrane)
uOl
Limestone, limestone breccia, and argillite
Limestone, limestone breccia, and argillite; Interbedded with uOll (Farewell Composite Terrane; Nixon Fork Subterrane)
Upper Ordivician fossils
mOl
Thick grainstone and micritic limestone
Middle Ordovician
Thick grainstone and micritic limestone (Farewell Composite Terrane; Nixon Fork Subterrane)
Middle Ordivician fauna
Limestone and argillite
Middle(?) and early Ordovician
Limestone and argillite; Thought to be equivalent to Novi Mt. Formation of Dutro and Patton, 1982 (Farewell Composite Terrane; Nixon Fork Subterrane)
Silty limestone and shale
Cambrian and Earliest Ordovician
Silty limestone and shale; essentially equivalent to Lyman Hills Formation in Dillinger Subterrane (Farewell Composite Terrane; Nixon Fork Subterrane)
Lyman Hills Formation, Silty limestone and shale
Ordovician and Cambrian
Silty limestone and shale; Lyman Hills Formation of Churkin and Carter, 1996 and Buntzen and others, 1997 (Farewell Composite Terrane; Dillinger Subterrane)
lOlb
Limestone breccia and micrite
Limestone breccia and micrite; Equivalent to Novi Mt. Formation of Dutro and Patton, 1982 (Farewell Composite Terrane; Nixon Fork Subterrane)
OCm
Banded mudstone
Banded mudstone; Believed by Grant Abbott, 1989, to be similar to a Middle Cambrian unit exposed near Hess River in Yukon (Farewell Composite Terrane; Nixon Fork Subterrane)
Clm
Limey, striped mudstone and siltstone
Middle (?) Cambrian
Limey, striped mudstone and siltstone; Probably equivalent to OCm (Farewell Composite Terrane; Nixon Fork Subterrane)
XCl
Oolitic limestone
Proterozoic to Early Cambrian
Oolitic limestone; same unit as Khuchaynik Dolomite of Babcock and others, 1994 (Farewell Composite Terrane; Nixon Fork Subterrane)
CZds
XCd
Oolitic, peletoidal dolomite
Oolitic, peletoidal dolomite; Probably Big River dolostone of Babcock and others, 1994 (Farewell Composite Terrane; Nixon Fork Subterrane)
Xmso
Red ferriginous shale and orthoquartzite
Red ferriginous shale and orthoquartzite;  Correlative with Windy Fork Formation of Babcock and others, 1994.  Also been called the Redstone Unit by Buntzen in 1984 (Farewell Composite Terrane; Nixon Fork Subterrane)
RB004
earliest Cretaceous (Neocomian) but may include Albian age strata
K-Ar date of 81.5 to 89.0 Ma from similar plutons in Melozitna quad., however later data suggests Latest Cretaceous or Early Tertiary age from Nulato quadrangle.
Gneissic rocks
Garnetiferous quartz-feldspar-biotite gneiss of almandine-amphibolite facies.  Also includes some quartzitic gneiss, amphibolitic gneiss, migmatite, small bodies of marble, and a few small bodies of granitic rock.
Metamorphic rocks (Pelitic schist)
Pelitic schist, quartzite, and calcareous to dolomitic marble, generally of greenschist facies.
Unconsolidated deposits
GG
Gabbroic phaciods in McHugh Complex
Jurassic and Late Triassic(?)
Strongly altered gabbroic phacoids that are tectonic inclusions in the McHugh Complex
VA004
Kuskokwim Group: Quartzose sublithic sandstone
Shallow marine to fluvial facies quartzose sublithic sandstone, siliceous shale, and siltstone;  part of Kuskokwim Group
Leaf hash, and brackish water pelecypods and minor coal
LH004
Kuskokwim Group: Sandstone and conglomerate
Shallow marine to fluvial facies coarse-grained sandstone and pebble-to-cobble conglomerate; minor very coarse-grained fluvial conglomerate and sandstone;  part of Kuskokwim Group
Kqvs
Kuskokwim Group: Sandstone
Shallow marine to fluvial facies coarse-grained sandstone-conglomerate rich in volcanic clasts;  part of Kuskokwim Group
Kuskokwim Group: Sandstone and siltstone
Deep water turbidite facies fine, medium, and coarse-grained sandstone and siltstone;  part of Kuskokwim Group
Kuskokwim Group: Turbidite facies
Deep water, very coarse-grained, turbidite facies (proximal fan); part of Kuskokwim Group
Kahiltna Assemblage: Turbidite sandstone and siltstone
Late Jurassic to Early Cretaceous
Fine-to-coarse grained turbidite sandstone and siltstone with minor fossil-rich, prismite-rich, limestone
Late Triassic age
Tholeiitic pillow basalt; part of Farewell Composite terrane and Mystic subterrane and equivalent to Tatina River Volcanics of Bundtzen and others, 1997
Volcanogenic sandstone and tuff
Volcanogenic sandstone and tuff; part of Farewell Composite terrane and Mystic subterrane
Late Triassic fossils
uMl
Fossiliferous limestone
Late Mississippian
Fossiliferous limestone with minor siltstone; part of Farewell Composite terrane and Mystic subterrane
PMl
Thick bedded, gray, fossiliferous, limestone; part of Farewell Composite terrane and Mystic subterrane
Fossiliferous (Frasnian)
Dsc
Shale and chert
Devonian (Gevitian to Frasnian)
Shale and chert; contains SEDEX barite deposits; part of Farewell Composite terrane and Mystic subterrane
Early Devonian (Emsian)
Thick bedded, dark-gray, limestone; part of Farewell Composite terrane and Mystic subterrane
Siltstone and sandstone
Devonian to Pennsylvanian
Brown siltstone and sandstone of Sheep Creek Formation after Bundtzen and others (1997) ; part of Farewell Composite terrane and Mystic subterrane
Pennsylvanian fusilinids and brachiopods
Pzmu
Mystic Subterrane, undivided
Devonian to Triassic
Mystic subterrane, part of Farewell Composite terrane
JDm
SDlw(h)
Massive micritic limestone
Late Silurian to Early Devonian
Massive micritic limestone karst rich and dolomitic; may be roughly equivalent to lower Whirlwind Creek Formation in Medfra and McGrath quadrangles; part of Farewell Composite terrane and Nixon Fork subterrane
Pzh
Holitna-Nixon Fork carbonates, undivided
Holitna-Nixon Fork carbonates, undivided; part of Farewell Composite terrane and Nixon Fork subterrane
DZn
Barren Ridge Limestone
Silurian to Devonian
Barren Ridge Limestone after Churkin and Carter (1996) and Bundtzen and others (1997);  part of Farewell Composite terrane and Dillinger subterrane
Terra Cotta Sandstone
Terra Cotta Sandstone after Churkin and Carter (1996) and Bundtzen and others (1997);  part of Farewell Composite terrane and Dillinger subterrane
Post River Formation
Ordovician to Silurian
Post River Formation after Churkin and Carter (1996) and Bundtzen and others (1997); part of Farewell Composite terrane and Dillinger subterrane
Lyman Hills Formation
Cambrian to Ordovician
Lyman Hills Formation after Bundtzen and others (1997); a separate mappable, lime rich zone (class 7582) is shown separately; part of Farewell Composite terrane and Dillinger subterrane
Gabbro-diorite sills, dikes, and volcanics
Paleozoic and Mesozoic
Gabbro-diorite sills, dike swarms, and mafic volcanics;  part of Farewell Composite terrane and Dillinger subterrane
Pzdu
Dillinger subterrane, undivided
Dillinger subterrane, undivided; part of Farewell Composite terrane
Coarse-grained granite
K/Ar of 55 Ma
Quartz monzonite dikes and plutons
Quartz monzonite dikes and small plutons
Basalt flows
K/Ar of 58 Ma
Felsite pluton
Cretaceous and Tertiary
Felsite pluton, age unknown
Quartz monzonite and diorite pluton
Quartz monzonite to diorite pluton with gold-copper skarn
K/Ar of 64 Ma
CI003
TKk
Kichatna pluton
Probably granite to tonalite
Alluvium, colluvium, and loess
Cretaceous-Tertiary
Medium- to coarse-grained equigranular to porphyritic biotite granite composed of anhedral quartz, anhedral to euhedral (porphyritic variety) K-feldspar, anhedral plagioclase and subhedral biotite
K-Ar age of 65.5 +/- 3.3 m.y. from biotite
Pzmi
Intermediate to mafic intrusive rocks
Fine- to medium-grained gabbro, subordinate quartz diorite, quartz monzonite, orthopyroxene gabbro, and pyroxenite.  Commonly sill-like.  Wallrocks are restricted to the Rampart Group
JPztm
Pzrgs
Rampart Group
Argillaceous and arenaceous rocks, siliceous and calcareous chemical sedimentary rocks and volcanic rocks.  Pzrgs is of a lower metamorphic grade than Pzrgmsv and consists of gray, green, black, and tan slate and siltstone interbedded with green to gray
Pzrgmsv
Argillaceous and arenaceous rocks, siliceous and calcareous chemical sedimentary rocks and volcanic rocks.  Pzrgmsv is of a higher metamorphic grade than Pzrgs and consists of phyllite or fine-grained quartz-muscovite-chlorite schist intercalated with me
Pzrp
Ruby Phyllite
Paleozoic (?)
Graphitic phyllite with minor interbedded graphitic quartzite and quartzite.  Locally fine-grained graphitic schist and graphitic quartz-mica schist.  Hornfelsed when adjacent to TKg (not shown on map)
Ruby Marble
Medium- to coarse-grained marble composed of calcite with minor musovite, pyrite, and diopside (?).  Probably correlative with Tamarack Bluff limestone
Pztbl
Tamarack Bluff Limestone
Marble and recrystallized limestone, dominantly fine- to coarse-grained calcitic marble, with some sedimentary structures preserved.  Probably correlative with Ruby Marble
Pelitic Schist
Precambrian and/or Paleozoic
Fine- to medium-grained graphitic quartz-muscovite +/- chlorite schist.  Minerology consistent with greenschist facies metamorphism
PzpCsg
Pelitic Schist and Gneiss
Medium- to coarse-grained quartz +/- muscovite +/- chlorite +/- biotite +/- grapphite +/- garnet +/- staurolite schist, quartzofeldspathic orthogneiss, and foliated greenstone.  Minerology consistant with amphibolite facies metamorphism
Volcanic and Sedimentary rocks
Tertiary (?) and/or Cretaceous (?)
Porphyritic basalt, andesite, and rhyolite flows, tuffs, and breccias with minor intercalated siltstone and sandstone
Graywacke, conglomerate and mudstone
Fine- to medium-grained graywacke, graywacke conglomerate with basalt, andesite, shale, chert, quartzite, and schist clasts, and green to gray mudstone.  Possibly correlative to graywacke of Rampart Group.
microfossils of probable Permian age
Chert and Slate
Thin-banded grey, green, and red chert with thin interbeds of slate
Chert contains radiolarians of Devonian, Mississippian(?), and Mississippian age
Undifferentiated Quaternary Deposits
Undifferentiated Quaternary deposits
TK003
Carbonate and Sandstone
Slightly calcareous interbedded polymictic conglomerate, lithic graywacke, siltstone and shale.  Correlative with Kahiltna flysch basin (or terrane) of Jones and others (1981) and the Gravina-Nutzotin flysch belt of Richter (1976)
late Jurassic fossil assemblage
Limestone and Shale
Light grey to dark grey carbonaceous limestone lenses and shale of the mafic metavolcanics and associated sediments of the Amphitheter Group
Monotis sp. of Late Triassic age
Trmb
Mafic Basalt
Very dark green-grey to reddish-oxidized, medium- to coarse-grained, mafic metabasalt of the mafic metavolcanics and associated sediments of the Amphitheter Group
Partial marine and subareal amygdaloidal basalt flows, basaltic and andesitic tuffs, flows, dikes, sills, and agglomerates
Dark to medium green, generally altered, partial marine and subareal amygdaloidal basalt flows, basaltic and andesitic tuffs, flows, dikes, sills, and agglomerates of the mafic metavolcanics and associated sediments of the Amphitheter Group
Tra
Pillow basalt and andesite
Submarine erruptive sequence of dark green, fine- to coarse-grained, pillow metabasalt and andesite of the mafic metavolcanics and associated sediments of the Amphitheter Group
Pac
Light grey to medium grey meta-argillite, metachert, and cherty argillite intercalated with very fine-grained siliceous aquagene tuff
Light grey to medium grey meta-argillite, metachert, and cherty argillite intercalated with very fine-grained siliceous aquagene tuff.  Low grade regional metamorphism.  Correlated with lower portions of the Tangle subterrane of Nokelberg and Fisher (198
Pvt
Meta-andesite flows, tuff, and metasandstone
Olive green, medium-grained volcaniclastic crystal lithic tuff, pyroxene-hornblende meta-andesite flows, and metasandstone.  Low grade regional metamorphism.  Correlated with lower portions of the Tangle subterrane of Nokelberg and Fisher (1989).  Sectio
lPsmv
Sheared mafic volcanic rocks
Medium greenish-grey, sheared meta-andesite and metadacite flow rocks.  Minor sheared lapilli tuff.  Low grade regional metamorphism.  Correlated with lower portions of the Tangle subterrane of Nokelberg and Fisher (1989).  Section includes the Mankomen
ulPla
Impure somewhat recrystallized siliceous bioclastic limestone, chert and minor quartzite
Light grey fine- to medium-grained, impure, siliceous bioclastic limestone with quartz and argillitic angular lithic detritus.  Chert and minor quartzite.  Low grade regional metamorphism.  Correlated with lower portions of the Tangle subterrane of Nokel
Late Wolcampian to Leonardian (middle to late Early Permian) and Leonardian to Guadolupian (late Early to Early Late Permian) conodonts
Pmvs
Metabasalt, meta-andesite, and metadacite
Undifferentiated altered volcanic flows, pyroclastics, and tuff.  Metabasalt, meta-andesite, and metadacite.  Low grade regional metamorphism.  Correlated with lower portions of the Tangle subterrane of Nokelberg and Fisher (1989).  Section includes the
Aquagene tuff, argillite and metasandstone
Dark grey to black, crystal-rich aquagene tuff with interbedded dark green-grey fine-grained volcaniclastic metasandstone and cherty argillite.  Low grade regional metamorphism.  Correlated with lower portions of the Tangle subterrane of Nokelberg and Fi
lPls
Silicious bioclastic limestone and argillite
Light- to medium-grey, very fine-grained, laminated siliceous bioclastic limestone composed of fine-grained carbonate, chert, angular quartz, and pelitic material.  Low grade regional metamorphism.  Correlated with lower portions of the Tangle subterrane
Crinoid columnal-rich carbonate layers yield late Wolfcampian conodonts
Tsk
Skarn
Skarn formed adjacent to TKif by lPls (not likely this unit)
uPzdt
Dolomite and metatuff
Distinctive white dolomitic marble and tan to green metatuff.  Regionally metamorphosed from prehnite-pumpellyite through lower greenschist to amphibolite metamorphic facies.  Correlated with the metamorphic complex of the Gulkana River of Nokelberg and
uPzfv
Silicified felsic metatuffs and metarhyolite to metadacite flows
Silicified felsic metatuffs and metarhyolite to metadacite flows intercalated with minor marble and dolomitic marble.  Regionally metamorphosed from prehnite-pumpellyite through lower greenschist to amphibolite metamorphic facies.  Correlated with the me
uPzsv
Mafic metabasalts, metaandesites, agglomerates, minor impure carbonates and pelitic semischists
Mafic metabasalts, metaandesites, agglomerates, minor impure carbonates, and pelitic semischists.  Regionally metamorphosed from prehnite-pumpellyite through lower greenschist to amphibolite metamorphic facies.  Correlated with the metamorphic complex of
uPzsl
Metapelites, mainly dark slate and phyllites
Metapelites, mainly dark slate and phyllites.  Regionally metamorphosed from prehnite-pumpellyite through lower greenschist to amphibolite metamorphic facies.  Correlated with the metamorphic complex of the Gulkana River of Nokelberg and others (1989) an
uPzas
Pelitic and mafic metavolcanic schist and amphibolite
Brown to grey, biotite-rich, quartz, feldspar, pelitic and mafic metavolcanic schist.  Massive, fine-grained hornblende amphibolite.  Regionally metamorphosed from prehnite-pumpellyite through lower greenschist to amphibolite metamorphic facies.  Correla
TKif
Felsite and fine grained granite plugs
Highly altered and weathered small bodies of felsite and fine grained granite plugs
Kqm
Medium-grained, equigranular biotite quartz monzonite
Probably similar to other Late Cretaceous plutons in the region radiometrically dated by Turner and Smith (1974)
Tqd
Medium- to coarse-grained, generally equigranular, hypidiomorphic pyroxene-hornblende diorite
Tqd-f
Foliated medium- to coarse-grained, generally equigranular, hypidiomorphic pyroxene-hornblende diorite
Tqd-p
Porphyritic medium- to coarse-grained, generally equigranular, hypidiomorphic pyroxene-hornblende diorite
Kgab
Medium to dark grey, eqigranular, pyroxene-hornblende rich gabbro
Mzms
Diorite, gabbro, picrite, and pyroxenite sill and dike swarm complex
Diorite, gabbro, picrite, and pyroxenite, ultramafic sill and dike swarm complex.  Also hypabyssal stocks and laccoliths
KJgd
Cretaceous and Jurassic
Light to medium grey, medium-grained equigranular to gneissic biotite-hornblende granodiorite
KJgd-f
Foliated Granodiorite
Foliated light to medium grey, medium-grained equigranular to gneissic biotite-hornblende granodiorite.  Unit not distinguished on map.
gossan
Trap
Pillow basalt and andesite displaying structures
Lava tubes and pillow structures of Tra, which is submarine erruptive sequence of dark green, fine- to coarse-grained, pillow metabasalt and andesite of the mafic metavolcanics and associated sediments of the Amphitheter Group
uPzsvh
Hornfelsed mafic metabasalts, metaandesites, agglomerates, minor impure carbonates and pelitic semischists
Hornfelsed mafic metabasalts, metaandesites, agglomerates, minor impure carbonates, and pelitic semischists.  Regionally metamorphosed from prehnite-pumpellyite through lower greenschist to amphibolite metamorphic facies.  Correlated with the metamorphic
Hf
Two outcrops within KJgd, on the southern boundary of the map.
TKir
May be a typo on the map.  If so, this is TKif
Kgd-f
In the Kqm description, a unit named Kgd is described as a quartz diorite.  This may be a foliated quartz diorite.  May also be a typo.  If so, it may be Kqd-f or KJgd-f.
KJgn
One outcrop on the southern boundary of the map.
uPzsm
KJwc
Wilber Creek and Wolverine quartzite units, undivided
Wilber Creek and Wolverine quartzite units, undivided (TN003 modified, shown as southern TrPs)
Carbonatite
Magnetite-rich carbonatite.
TN004
Dql
Quail unit, basal limestone
Local biogenic limestone buildups in basal Quail unit, deposited on the Troublsome unit.  Are as much as 30 m thick and have a lateral extent of several hundred meters.
Two small plutons in the se part of quadrangle.  Fine- to medium-grained  hornblende-biotite granodiorite with subordinate quartz monzonite and quartz diorite.  Distinguished from others to the north by Bill Patton (March, 1999)
Quail unit, revision
Conglomerate, phyllite, calc-phyllite, siltstone, and sandstone.  Part of unit recorrelated to Cascaden Ridge equil.
Dt
Troublesome unit
Devonian(?)
Argillite, chert, and mafic intrusive and extrusive rocks
Mog
Orthogneiss
U/Pb age 350 Ma, protolith(?) age
LG003
Rampart Group volcanic and sedimentary rock sequence, mafic rocks divided out
Carbonatite of unit Jsc
Kwcq
Wilber Creek unit of Weber and others (1992), quartzite
Brown, argillaceous, impure quartzite and graywacke sandstone; locally mappable within dominantly argillaceous and graywacke section.
JMtru
Uncertain but believe to be early Paleozoic or Precambrian
Birch Creek Schist, part correlated with Spruce Creek sequence of Kantishna Hills from Bundtzen thesis
Mississippian or Devonian
Metavolcanic and metavolcaniclastic rocks. Unit added based on Bundtzen and Weber
KH005
Granite?
Unit not described on source map -- missing from legend
Lead-alpha age 55-60 Ma, highly suspect.
RB005
probably Late Cretaceous and Early Cretaceous
Chiefly quartz monzonite in Kokrines Hills
K-Ar date of 111 Ma in Melozitna quad.
Unk
Where did this come from?
RB?
The younger unit, mcb, contains schist and quatzite with some crystalline limestone, slate, and greenstone.  Part of unit recorrelated (D.N. Bradley, USGS, pers commun., 1998)
pCm
Meta-quartz diorite
middle Proterozoic?
Sheared metamorphosed porphyritic quartz diorite
K-Ar on biotite 921 +/- 25 Ma, mouscovite in border zone 663+/- 20 Ma
RB007
Ynqd
Mostly gray, fine- to medium-grained quartzite, interlayered with mostly gray, greenish-gray, reddish-gray, and tan argillite (1 northwesternmost polygon at CI-LG quad boundary
Chloritized porphyritc (hornblende) biotite monzograinte.  Also includes rocks mapped as units Kgp and Kgrd, granite or granodiorite(?) porphyry and granodiorite.
K-Ar ages range from 57 +/- 2Ma to 71 +/- 2 Ma;  Ar-Ar studies suggest a likely age of 90 Ma
CI005
Paleozoic or preCambrian
Gabbro and diorite and some sedimentary rocks of unknown affinity
Various limestone symbol shown on Circle map in a variety of rock units.  No further description in text.  Includes on southern polygons of unit
ch
Various chert symbols shown on Circle map in a variety of rock units.  No further description in text.  Assigned to Rampart-Tozitna sedimentary rock unit on the basis of location.
Quartzite and quartzitic schists
Gray or greenish-gray quartzite and quartzitic schists are dominant rock types.  Minor pelitic schist, calc-silicate, mafic schist, and rare marble are interlayered with quartzite and quartzitic schists.
Gray, maroon, and green slaty argillite interlayered with gray and greenish-gray grit and quartzite.  Minor limestone in southern part of exposure.  Western exposures in part.
Chiefly dark-greenish gray to pale-olive tuffaceous and feldspathic fine-to-very coarse-grained sandstone.  Subordinate dark-gray mudstone.  Many sandstone beds distinctly mottled due to partial zeolitization of volcanic material.
Association and gradational(?) with units containing Buchia of earliest Cretaceous age.
Andesitic volcanic rocks - Roundabout Mountain volcanic field
KT003
Undifferientiated units Km and Kn.  Units on east side of quadrangle reassigned to unit Kvg (NSA 2180).
Lime rich zone in the Lyman Hills Formation after Bundtzen and others (1997); part of Farewell Composite terrane and Dillinger subterrane
Diorite, monzonite, and quartz syenite
Light to medium-gray biotite-aegerine-olivine diorite, monzonite, and subordinate quartz syenite.  Forms bulk of Cripple Creek Mountains pluton.
K-Ar age of 71.3 Ma
MD003
OP003
Kcvs/Kcs
Coarse-grained volcaniclastic sandstone and conglomerate
Greenish gray, poorly sorted fine- to coarse-grained lithic-volcaniclastic sandstone and pebble conglomerate composed chiefly of volcanic rock and chert detritus, and quartz.
OCl
Unit not described.  Sinlge polygon located north of coal-bearing sedimentary rocks in the southwestern McGrath quadrangle.
Greenschist and quartz mica schist
Medium-gray to medium-green, medium- to coarse-grained, schistose, foliated, actinolite-chlorite-epidote greenschist and biotite-chlorite-albite-quartz schist.
Banded chert and argillite
Medium- to dark-gray, green, and some red radiolarian chert. interbedded dark-gray argillite, and very minor tuffaceous volcanic rocks
JTrt; JTrma
Siliceous tuff, crystal and lithic tuffs, and metasiltstone and Mafic volcanic breccia, tuff, siltstone, chert, and agglomerate
Triassic and early Jurassic
Radiolaria and conodonts reported by Patton and others, 1980 (MD002)
TrMv; TrMcs
Mafic tuff, volcaniclastic sandstone, and minor mafic flows and Calcareous, lithic pebble sandstone
Medium- to dark-gray, coarse-grained augite-plagioclase-rich mafic tuff, volcaniclastic sandstone, and porphyritic basaltic andesite and basalt.  Also, light- to medium-green-gray, medium- to coarse-grained, commonly calcareous lithic pebble sandstone an
Veghicyclia spp., Pseudoheliodiscus spp., and Sarla spp. of Norian age and Crytostome bryozoan, brachiopod and pelmatozoan fragments of probable late Paleozoic age
Augen orthogniess
Gnessic phase in southern part of the Melozitna pluton now recognized as augen orthogneiss.
Pelitic and quartzose schist sequence, recoded as Wickersham on northern part of map.
Pelitic and quartzose schist sequence.  Reclassified single polygon on the northeast part of map
Ksu?
Sandstone, shale, and conglomerate marine and nonmarine deltaic deposits in south and east part of quadrangle
Graywacke and mudstone turbidite deposits.  Polygons north of Kaltag fault on west side of quadrangle of this unit reassigned to unit Ksm
Graywacke and mudstone turbidite deposits.  Polygons in extreme northwest of quadrangle of this unit reassigned to unit Kgw on DOG map, lumped back by W.W. Patton, Jr., (1999)
Medium- to dark-gray, green, and some red radiolarian chert, interbedded dark-gray argillite, and very minor tuffaceous volcanic rocks.
Albaillella sp.(Middle and Late Mississippian), Latentibifistula sp. (Pennsylvanian and Permian), Capnodoce sp. (Triassic?)
Schistose metamorphic rocks -- Unit on northern edge of map recorrelated based on information from Bill Patton
Sandstone, grit, and argillite -- some polygons in northeast part of map reassigned to unit PzpCph, per Bundtzen and others (1997)
Dishna River mafic and ultramafic rocks extension into Ophir quadrangle
TKva
Basaltic andesite, basalt, and lapilli tuff
Tertiary(?) and Cretaceous
Medium-greenish-gray, aphanitic to fine-grained, porphyritic, hornblende-rich basaltic andesite; uncommon basalt and very fine grained lapilli tuff(?)
Undifferentiated sedimentary rocks -- conglomerate facies
Sandstone, shale, and conglomerate marine and nonmarine deltaic deposits in southwest part of quadrangle.  Addition of subdivision by W.W. Patton, Jr., 1999
NL004
Kccf