Qu
BR003
Unconsolidated and poorly consolidated sediments, undivided
Surficial material deposited by water, wind, freeze-thaw cycles, and glaciers
Quaternary
Black River
Sedimentary
BT004
Bettles
BV003
Beaver
CH003
Chandalar
CI006
Circle
CO003
Coleen
CS003
Christian
CY006
Charley River
FY004
Fort Yukon
LG005
Livengood
TN009
Tanana
WI005
Wiseman
Ts
Clasitc sedimentary rocks
Mudstone, coal, sandstone, and conglomerate deposited in lacustrine and fluvial environments
Tertiary
In the southern and western part of the map area:  Paleocene, Eocene, Oligocene and Miocene pollen have been recovered from several sites (Weber and others, 1994, Chapman and others, 1982, unpublished oil industry data, written commun., 2002).
Tb
Basalt flows and rare cinder cones
Vesicular, massive olivine basalt flows that range from 20 to 300 m thick
40Ar/39Ar ages range from 15.7+/-0.1 to 14.4+/-0.1 Ma (Kunk and others, 1994).
Igneous
Tv
Volcanic rocks
Locally thick packages that include basalt, andesite, dacite, and rhyolite flows and domes
West side of the Ruby geanticline:  Hornblende and biotite K/Ar ages from exposures near the bottom of the sequence yielded ages of 59.5 +/- 1.7 and 59.6 +/- 1.8 Ma respectively (Patton and Miller, 1973); a flow in an uncertain position in the sequence y
Tg
Granitic rocks
Quartz monzonite, biotite granite, and alaskite
The pluton on the Yukon River yielded a U-Pb zircon age of 60.5 +/- 0.2 Ma; the Manley pluton, on the southern boundary of the map area in the Tanana quadrangle, yielded a U-Pb zircon age of 60.9 +/- 1.0 Ma (A.B.Till, unpub. data).   40Ar/39Ar ages have
TKs
Sedimentary rocks
Sandstone, mudstone, thin coal seems, and conglomerate exposed in the Takonduk and Rampart areas.
Tertiary and Cretaceous
Late Cretaceous, Paleocene, and Eocene pollen have been recovered from exposures within and immediately south of the map area (Miyaoka, 1990), and from shallow core holes (unpublished oil industry data, written commun., 2002).
In the western Rampart area
Kkyu
Sedimentary rocks of the Yukon-Koyukuk basin, undivided
Marine volcanic-clast conglomerate, graywacke, sandstone, mudstone, shale, calcareous sandstone, siltstone and shale, and minor non-marine sandstone and shale.
Cretaceous
Mollusks from the marine part of the unit are Albian; rare plant fossils from the non-marine part of the section range from late Early Cretaceous to Late Cretaceous in age (Patton and others, in press).
Kku
Sedimentary rocks of the Kandik basin, undivided
Carbonaceous shale, siltstone, quartz arenite, argillite, graywacke, sandstone, and conglomerate; parts of the section are rich in volcanic clasts.
Early Cretaceous (Valanginian and Berriasian) megafossils have been identified. Although correlations have been made between units in the Kandik basin and units in the Manley basin that contain Albian fossils (Dover, 1994), no unequivocally Albian strata
Kg
Small plugs to large, batholithic plutons
Ruby geanticline plutons are generally evolved and yield U-Pb zircon and K/Ar ages of 112-90 Ma (Patton and others, 1994). In the Manley basin and western Yukon-Tanana Upland, plutons are slightly younger; they have yielded K/Ar and 40Ar/39Ar ages that r
KJu
Sedimentary rocks, undifferentiated
Scattered occurrences of shale, argillite and quartzite up to 300m thick.
Cretaceous? and Jurassic?
Bivalves of Jurassic or Cretaceous age reported from one exposure in the Coleen quadrangle (Brosgé and Reiser, 1969).
Mzmv
Fine-graned sedimentary rocks and tuff
Slate, shale, siltstone, argillite, tuff, and minor quartzite and conglomerate
KJg
Glenn Shale, upper part
Carbonaceous shale that contains minor thin (up to 5m) beds of fine-grained sandstone
Late Cretaceous and Jurassic?
Early Cretaceous megafossils have been collected from several localities within the unit (Miyaoka, 1990).
JMsu
Strangle Woman Creek sequence of Brosge' and Reiser (1969), undivided
Rock types include very fine grained to conglomeratic sandstone; gray limestone and dolostone; dark gray, very fine grained, thin-bedded limestone and black chert; and coarse-grained, conglomeratic, quartz sandstone that contain minor potassium feldspar
Jurassic to Mississippian
Early Jurassic (Hettangian) ammonites (Brosgé and Reiser (1969).  Unit also contains Permian or Carboniferous brachiopods and corals and Late Mississippian corals (Brosgé and Reiser, 1969), as well as tightly dated Carboniferous conodonts.  Conodont faun
JMpu
Younger strata of the Porcupine River sequence of Brosge' and Reiser (1969), undivided
Main rock types are ferruginous, very fine grained sandstone; gray to black pyritic siltstone and silty shale; laminated, red and green chert; silty, shaly, and cherty limestone; coarse-grained to conglomeratic, locally feldspathic sandstone, mafic flows
Carboniferous, Permian, and Jurassic megafauna are reported (Brosgé and Reiser, 1969).
KJmu
Sedimentary rocks of the Manley basin, undivided
Quartzite, shale, siltstone, graywacke, polymictic conglomerate
Cretaceous and Jurassic
Older parts of the unit contain marine megafauna of Jurassic and Early Cretaceous (including Albian) age and the Minto unit has yielded plant fossils of Late Cretaceous(?) age (Weber and others, 1994).
TrPs
Argillite, siltstone, sandstone, shale, chert, limestone, conglomerate, and limestone debris flows.  The unit is structurally imbricated with the sedimentary rocks of the Manley basin (KJmu).
Triassic? to early Permian
Conodonts, foraminifera, and megafossils yielded Permian and less definite late Paleozoic ages (Weber and others, 1994); Triassic Radiolaria were also recovered (Weber and others,1992).
TrPgt
Glenn Shale, lower part, and Tahkandit Limestone, undivided
Thin-bedded fossiliferous limestone, calcareous shale and rare thin oil shale of the lower part of the Glenn Shale, and massive bioclastic limestone, glauconitic sandstone, and minor chert pebble conglomerate of the Tahkandit Limestone
Triassic and Permian
In the central Yukon-Tanana province, exposures of this unit are lithologically similar to the lower part of the Glenn Shale and have yielded Permian to Triassic conodonts (Weber and others, 1994).  In the southern part of the Porcupine province, the low
PCta
Sedimentary rocks of the Tatonduk area
Limestone, argillite, shale, chert, quartz arenite and conglomerate exposed in the southern part of the Porcupine province.
Permian to Cambrian
JDat
Angayucham-Tozitna terrane, undivided
Lithologically diverse, structurally imbricated igneous and sedimentary rocks of oceanic affinity exposed on all flanks of the Yukon Flats basin. Igneous rocks include ultramafic, mafic extrusive and intrusive, andesitic, and rare dacitic to rhyolitic ig
Late Jurassic to Devonian
Radiolarians, conodonts, and pollen from sedimentary rocks interlayered with the mafic rocks and from the predominantly sedimentary sections yielded ages of Devonian, Mississippian, Pennsylvanian, Permian, Triassic, and Early Jurassic.
Hornblende from four exposures of gabbro in the Rampart area and Christian quadrangle have yielded K-Ar ages that range from 207 to 174 Ma (Brosgé and others, 1969; Brosgé and Reiser, 2000), but low potassium contents of the amphiboles (and low radiogeni
MzPza
Low-grade metamorphic rocks
Phyllite, argillaceous metachert, limestone, and associated mafic rocks.
Mesozoic? and Paleozoic
Metamorphic
TrPzd
Metasedimentary and metavolcanic rocks, sedimentary rocks of the Doonerak area
Fine-grained metasedimentary rocks that contain lenticular bodies of carbonate rocks; metavolcanic and metavolcaniclastic rocks of island arc affinity, and a thin sequence of shale, siltstone and limestone (Dillon and others, 1986; Moore and others, 1994
Triassic to late Paleozoic
Cambrian, Ordovician, and Silurian megafossils have been recovered from the metasedimentary rocks (Moore and others, 1994).
Pzvu
Sedimentary rocks of the Venetie terrane of Silberling and others (1994), undivided
Lithic and quartz wacke, metamorphosed wacke, metasandstone, phyllite, slate, shale, quartzite, chert, and minor greenstone (Brosgé and Reiser, 2000).
Paleozoic
Devonian (?) plants and spores, Mississippian (?) Radiolaria, and Permian conodonts have been recovered from this unit.
Pzcm
Metamorphic rocks
Semischist, phyllite, and thin layers of mafic rock exposed in the extreme northeast corner of the Porcupine province.  Rocks are generally fine grained, and the metamorphic assemblage locally includes biotite and garnet. Contact with adjacent granite is
Paleozoic?
Pzum
Ultramafic rocks
Serpentinite and lesser gabbro and rodingite rubble
Hornblende from gabbro has yielded a disturbed 40Ar/39Ar age spectrum suggestive of early Paleozoic age (Reifenstuhl and others, 1998).
DZs
Metamorphosed sedimentary rocks
Variably metamorphosed and deformed shale, siltstone, fine- to medium-grained sandstone, graywacke, quartz and chert wacke, and minor conglomerate, carbonate, and mafic rocks.  Quartz-rich rocks that contain chert clasts are common. Sedimentary structure
Devonian to Proterozoic
Five localities in the large exposure of the unit in the central Tanana quadrangle yielded Late Devonian (Famennian) conodonts (A.G. Harris, USGS Emeritus, written commun., 2000).
Detrital zircon populations have been used to coorelate this unit with others (see description).
Pzqs
Sedimentary and igneous rocks
Quartz-rich sedimentary rocks, associated carbonate rocks and minor mafic volcanic rocks.
Permian, Carboniferous, and Devonian
In the Charley River quadrangle the unit also includes shale, argillite, and limestone that contains Permian and Carboniferous brachiopods (Brabb and Churkin, 1969).
KDe
Sedimentary rocks of the Endicott Mountains allochthon of Moore and others (1994)
Thick marine and non-marine sedimentary sequence dominated by Devonian and Mississippian clastic and carbonate rocks of the Endicott and Lisburne Groups (Moore and others, 1994)
Cretaceous to Devonian
Mbu
Rocks of Brooks Range sequence of Brosge' and Reiser (2000), undivided
Consists of gray to brown, fine- to medium-grained, partly crinoidal limestone (Lisburne Group); black shale, laminated siltstone, chert, and orange-weathering limestone (Kayak Shale); and unnamed black siltstone and shaly phosphatic limestone (Brosgé an
Mississippian
Contains mega- and microfossils of Mississippian age.
DCpu
Older strata of the Porcupine River sequence of Brosge' and Reiser (1969), undivided
Succession includes dark gray limestone and lesser dolostone and light to dark gray, locally mottled dolostone and limestone.  Subordinate lithologies are gray and black chert, black shale, red and green shale and sandstone, and limestone cobble conglome
Devonian to Cambrian
Limestone and lesser dolostone contain Middle Devonian corals.  Most precise ages for older part of succession based on Late Silurian and Late(?) Ordovician corals and Cambrian(?) trilobites (Brosgé and Reiser, 1969).  Conodonts of Early Silurian and mid
DSc
Chert and chert-pebble conglomerate, calcarenite, conglomeratic limestone, limestone, metasiltstone and argillite, mafic intrusive rocks, and rare dolostone.
Devonian and Silurian
Conodonts recovered from the unit have broad age ranges, are Late Devonian (Famennian) or are Silurian in age (A.G. Harris, USGS Emeritus, written commun., 2000).  Silurian conodonts were collected along the northern contact of DSc and may be from a faul
Cg
Granite
Granite and quartz monzonite, exposed in large body on the northeast boundary of the map.  Northern contact with adjacent metamorphic rocks is intrusive; southern boundary is shown as a fault but is not well exposed nor well understood.
Carboniferous
K/Ar mica ages range from 354 to 302 Ma (Brosgé and Reiser, 1969).
CPt
Sedimentary rocks of the Tindir Group
Phyllite, slate, siltstone, argillite, quartzite, red beds, carbonate-clast conglomerate, dolostone, limestone, basalt, chert, and glacial diamictite exposed in the southeast part of the Porcupine province.  See Dover (1994) for a summary of the formal u
Cambrian? and Proterozoic
The Cambrian(?) age is based on several occurrences of the trace fossil Oldhamia (Miyaoka, 1990).
PzZl
Sedimentary and igneous rocks corresponding to the Livengood area swquence of Weber and others (1992)
Argillite, phyllite, quartzite, graywacke, siltite, grit and limestone of the Wickersham unit; mafic intrusive and extrusive rocks and fine grained sedimentary rocks interlayered with serpentinite, equivalent to "PzZm" and "CZum" units; dolomite, chert,
Paleozoic to Proterozoic
Weber and others (1994) reported all paleontologic control on the age the rocks in this unit. Late Ordovician graptolites were recovered from sedimentary rocks of the Livengood Dome Chert; megafossils from the lime mudstone of the Lost Creek unit are Sil
Gabbro associated with the serpentinite of "CZum" yielded a 40Ar/39Ar hornblende age of 535.3 +/-  2.7 Ma (Athey and others, 2004).
PzZw
Sedimentary and igneous rocks corresponding to the older parts of the Fairbanks-White Mountains area sequence of Weber and others (1992)
Argillite, grit, quartzite, graywacke, phyllite, limestone, and dolomite, equivalent to the Wickersham unit;  alkali basalt, agglomerate, volcanic conglomerate, and associated limestone, sandstone and chert, equivalent to the Fossil Creek Volcanics; muds
All fossil ages for the unit are reported in Weber and others (1994).  The part of the sequence that includes the grit contains the Precambrian to Cambrian trace fossil Oldhamia; sedimentary rocks associated with the alkali basalt yielded mega-and micro-
PzZs
Sedimentary and igneous rocks corresponding to older parts of the Schwatka-Rampart area sequence of Webber and others (1992)
Grit, argillite, quartzite, siltite, graywacke, phyllite, and minor limestone; interlayered mafic volcanic rocks and limestone, minor associated greenstone, limestone, and limestone debris flows, and a group of fine-grained metamorphic and sedimentary ro
The part of the sequence that includes the grit yielded the trace fossil Oldhamia, of Precambrian to Cambrian age; limestone interlayered with mafic volcanic rocks yielded Devonian megafossils and Early and Middle Devonian conodonts (Weber and others, 19
PzpCy
Metamorphic rocks of the Yukon-Tanana Upland, undivided
Fault-bounded assemblages of lithologically and metamorphically distinct metaigneous and metasedimentary rocks that have Paleozoic and Precambrian(?) protoliths.  Structurally lower assemblages, most with continental affinities, have been deformed in a d
Paleozoic to Precambrian?
U-Pb dates (see description)
PzpCh
Metasedimentary and metaigneous rocks of the Hammond terrane
Thick sequences of lower Paleozoic metacarbonate rocks commonly called the Skajit Limestone (Moore and others, 1994), thick sequences of metasiliciclastics, metamorphosed calcareous sedimentary rocks, and minor mafic metagabbro and metafelsite exposed im
Paleozoic and (or) Precambrian
Cambrian, Ordovician, Silurian, and Devonian fossils have been collected within the area shown on this map (Dumoulin and Harris, 1994).  Lower Paleozoic rocks contain fauna that have Siberian affinities (Dumoulin and others, 2002).
PzpCm
Pelitic schist, amphibolite, metaquartzite, marble, and granitic orthogneiss that occur as three lenses in or near the Kobuk and Victoria Creek fault systems.  Not all lithologies are found in all three lenses.  Protolith ages are unknown.   Metamorphic
Paleozoic and (or) Precambrian?
The southern of two lenses along the Victoria Creek fault yielded three biotite and white mica 40Ar/39Ar ages of 61 Ma (Reifenstuhl and others, 1997a), which are interpreted as metamorphic cooling ages.  One of the lenses along the Kobuk fault system yie
PzpCb
Metasedimentary and metaigneous rocks of the southern Brooks Range and Ruby geanticline
Quartz-mica schist and lesser calcareous schist, marble, mafic schist, and granitic orthogneiss, exposed along the southern Brooks Range and axis of the Ruby geanticline.
Early Devonian microfossils were collected from marble in the Wiseman quadrangle (Moore and others, 1997).
U-Pb zircon ages from orthogneisses, which occur in both the Brooks Range and the Ruby geanticline, are Middle Devonian (Aleinikoff and others, 1993; Patton and others, 1987).