ÛáMAP_UNITC UNIT_NAMECpAGEC'DESCRIPTIOCþFOSSILC±RADIOMETRICƒSOURCECCLASSNQUADRANGLECROCK_CLASSC NSACLASSNLABELCNSAMODCQCLASSN Qs Surficial sedimentary deposits, undivided Quaternary Frost-rived rubble on slopes and broad low ridges; glacially deposted sand, gravel, and boulders; fluvial gravel and sand; terrace deposits. AR0042040Ambler River Sedimentary100 1000 Ks Conglomerate, sandstone, and shale Cretaceous Conglomerate and finer grained sedimentary rocks that grade from massive, poorly stratified rocks rich in mafic intrusive and extrusive clasts at the base of the unit to a well-sorted sedimentary rock rich in quartz and metagraywacke clasts at the top ofSparse plant fossils of Early to Late Cretaceous age; Early Cretaceous? marine mollusks AR0042038Ambler River Sedimentary1990 MzPzs Serpentinite Mesozoic? to Paleozoic? Greenish-gray, yellowish-green, olive green or greenish black serpentinite, minor basaltic rocks, harzburgite tectonite, and nephrite jade exposed in the southern Ambler River and adjacent Shungnak quadrangles. In the Cosmos Hills fault-bounded serpentin AR0042073Ambler River Metamorphic3498 JDab Mafic metavolcanic and metaintrusive rocks, metachert, metalimestone, and amphibolite of the Angayucham terrane Early Jurassic to Devonian Metamorphosed pillow basalt, hyaloclastic breccia, basaltic tuff, diabase, microgabbro, radiolarian and tuffaceous chert, minor metalimestone, and rare mafic schist in an imbricate package exposed along the southern boundary of the map area. Commonly, meRadiolarians, conodonts, megafossils, foraminifers, bryozoans, brachiopods AR0042009Ambler River Metamorphic5133 KJm Melange Cretaceous to Jurassic Tectonic assemblage of meter to kilometer-scale fault slivers of pillow basalt, mafic schist, metagabbro, metalimestone, metachert, metagraywacke, phyllite, and rare serpentinite exposed in low hills in the south central and southwestern part of the map Radiolarians, conodonts AR0042092Ambler River Metamorphic5145 DSc Carbonate rocks of Cosmos Hills Devonian and Silurian Thin-bedded to massive dolostone, metalimestone, and marble, locally graphitic or phyllitic exposed in fault slices in the Cosmos Hills. Minor thin, micaceous layers interpreted as airfall tuffs, and some buff to reddish gray dolostones thought to be of Conodonts, brachiopods, gastropods, crinoids, tabulate and rugose corals, stromatoporoids AR0042084Ambler River Metamorphic5525 Pzp Phyllite Paleozoic? Phyllite, fine-grained schist, and phyllonite of the Central belt that underlie areas of poor exposure in the northeastern Baird Mountains quadrangle, western Ambler River quadrangle, and northwestern Chandalar quadrangle. Locally contains minor lenses AR0042030Ambler River Metamorphic5560 Pzpg Phyllite and graywacke Paleozoic? Dark gray to black phyllite and brown-weathering greywacke, sandstone, and mudstone exposed along the southern boundary of the schist belt. The unit varies in breadth along strike. In the Wiseman and Chandalar quadrangles, two subunits are recognized: AR0042007Ambler River Metamorphic5565 Pzpc Carbonate rocks of Phyllite belt Paleozoic Fault-bounded blocks of marble, metalimestone, and dolostone that crop out in southwestern Ambler River quadrangle. Carbonate rocks are locally intercalated with black phyllite, black metaquartzite, and metachert, contain megafossils (corals, brachiopodCorals, brachiopods, crinoid debris, conodonts AR0042086Ambler River Metamorphic5570 Mkkl Kekiktuk Conglomerate(?), Kayak Shale of Endicott Group and Lisburne Group Mississippian Quartzite, conglomerate, phyllite, metalimestone, slate, dolostone, marble and chert. Succession occurs in several fault-bounded exposures in the east-central Ambler River quadrangle. Echinoderm debris, brachiopods, mollusks, cephalopods, and plant fragments AR0042088Ambler River Metamorphic6305 Mc Quartz-rich conglomerate Mississippian? Quartz- , chert-, quartzite-, and slate-clast conglomerate with minor thin layers of metasandstone and phyllite exposed in the Ambler River, Survey Pass, and Wiseman quadrangles. Quartz and chert clasts are most common; chert clasts are varicolored. Th AR0042077Ambler River Metamorphic6360 Mu Metasedimentary rocks, undivided Mississippian Quartz conglomerate, quartzite, metasandstone, phyllite, shale, and metalimestone in the Ambler River, Survey Pass, and Wiseman quadrangles. Crinoids, brachiopods, corals, foraminifers, gastropods, molluscan and echinoderm debris, possible bryozoan, pelecypod, brachiopod, ostracode fragments, foraminifers AR0042062Ambler River Metamorphic6365 Spl Black phyllite and metalimestone Silurian Black siliceous phyllite and metalimestone, metasandstone, metasiltstone, phyllite, and graphitic calcareous schist in the eastern Ambler River and western Survey Pass quandrangles. This unit is part of the Central belt. Mapped as units Dbl and Db by MConodonts, graptolites, radiolarians; corals, gastropods, bryozoans, brachiopods, conularids, and orthocone cephalopods AR0042049Ambler River Metamorphic6686 Dn Noatak Sandstone Devonian Consists of metasandstone and metasiltstone with subordinate interlayers of green, gray, and maroon phyllite and local ironstone concretions. Semischistose textures and minerals indicative of lower greenschist facies metamorphism occur locally, but origiLate Devonian (some Famennian)conodonts, brachiopods, echinoderms, gastropods, pelecypods, plant debris, and trace fossils AR0042056Ambler River Metamorphic6900 MDk Kanuyut Conglomerate Lower Mississippian? and Upper DevonianQuartzite, pebbly quartzite, conglomerte, and minor siltstone. Exposed in a few small areas of northwestern Baird Mountains quadrangle, northeastern Ambler River quadrangle, and widely distributed in northern Survey Pass quadrangle. Semischistose and myEchinoderm debris, brachiopods, mollusks, cephalopods, and plant fragments AR0042028Ambler River Metamorphic6915 Dhf Hunt Fork Shale Late Devonian Dark gray to black phyllite and lesser gray-green phyllite with thin layers of siliceous or calcareous metasiltstone, lithic wacke, metasandstone, and minor layers of fossiliferous metalimestone exposed along the length of the northern boundary of the maBrachiopods (late Frasnian to early Fammenian), mollusks, echinoderms; Middle to Late Devonian conodonts; AR0042018Ambler River Metamorphic6925 Dmu Metasedimentary and lesser metaigneous rocks Middle and Late Devonian Heterogeneous expanses of calcareous, siliceous, and volcaniclastic metasedimentary rocks, with lesser metaigneous rocks, exposed along the length of the Central belt. Includes significant expanses of rocks mapped as Beaucoup Formation by some workers. TMegafossils and conodonts are Middle and early Late Devonian U-Pb zircon crystallization age of 393+/-2 Ma from subunit that contains felsic to intermediate volcanic rocks AR0042017Ambler River Metamorphic6927 Dmu_542 Metasedimentary and lesser metaigneous rocks, calcareous, iron-rich components Middle and Late Devonian Part of heterogeneous expanses of calcareous, siliceous, and volcaniclastic metasedimentary rocks, with lesser metaigneous rocks, exposed along the length of the Central belt. This part of the unit contains a light brown, gray, and orange-weathering ferMegafossils and conodonts are Middle and early Late Devonian U-Pb zircon crystallization age of 393+/-2 Ma from subunit that contains felsic to intermediate volcanic rocks AR0042052Ambler River Metamorphic6972 Dmu_541 Metasedimentary and lesser metaigneous rocks, volcanic-rock bearing subunit Middle and Late Devonian Part of heterogeneous expanses of calcareous, siliceous, and volcaniclastic metasedimentary rocks, with lesser metaigneous rocks, exposed along the length of the Central belt, thought to be correlative with the Beaucoup Formation. This subunit containMegafossils and conodonts are Middle and early Late Devonian U-Pb zircon crystallization age of 393+/-2 Ma from a foliated felsic rock AR0042043Ambler River Metamorphic6973 DOc Younger carbonate rocks of the Nanielik Antiform, Central belt and part of Northern Thrust Assemblages Middle Devonian to Ordovician Very light- to dark-gray- (locally orange-) weathering, gray to black, commonly massive dolostone and lesser metalimestone and marble exposed in the northeastern Baird Mountains quadrangle in the Nanielik antiform and in the northwestern Chandalar quadraConodonts, corals, stromatoporoids AR0042016Ambler River Metamorphic6980 Pzm Marble Paleozoic White to gray (less commonly black), fine to coarsely crystalline, massive to platy marble and subordinate metalimestone and dolostone occurs discontinuously in all quadrangles within the map area. This unit is part of the Central belt. Conodonts, silicified two-hole crinoid columnals of late Early-early Middle Devonian (late Emsian-Eifelian) age; brachiopods; possible stromatoporoids; pelmatozoan; trilobites AR0042023Ambler River Metamorphic6983 Pzsg Mafic schist Paleozoic Green and greenish-gray schistose to massive irregularly-shaped bodies and lenses of mafic rocks in units Dsq and DPsc large enough to show at the scale of the map occur in the Survey Pass and Chandalar quadrangles. This unit is part of the Schist belt. AR0042006Ambler River Metamorphic7000 Pzsm Marble of the Schist belt Paleozoic Metacarbonate rocks that form an elongate belt in the central Ambler River quadrangle and are the only mappable occurrence of carbonate strata in the Schist belt. Unit surrounds the Redstone pluton and includes a variety of rock types. White, gray, and bConodonts, corals, stromatoporoids, spines, and echinoderm debris AR0042087Ambler River Metamorphic7215 Dhf_101 Hunt Fork Shale - foliated exposures Late Devonian Dark gray to black phyllite and lesser gray-green phyllite with thin layers of siliceous or calcareous metasiltstone, lithic wacke, metasandstone, and minor layers of fossiliferous metalimestone exposed along the length of the northern boundary of the maBrachiopods (late Frasnian to early Fammenian), mollusks, echinoderms; Middle to Late Devonian conodonts; AR0042044Ambler River Metamorphic7225 Pzb Black phyllite and siliceous phyllite Paleozoic? Gray to dark gray carbonaceous phyllite, locally silica rich, exposed in the Central belt in the western Ambler River quadrangle. This unit is part of the Central belt. AR0042066Ambler River Metamorphic7235 Dg Granitic orthogneiss Devonian Tan to gray weathering, equigranular to porphyroblastic, fine to coarse grained metagranitic bodies ranging in size from less than a kilometer to over 20 kms across, found in both the Schist and Central belts. Generally granitic in composition and made U-Pb zircon dates for orthogneiss 390-396 Ma; 375-395 Ma for orthogneiss at Mt. Igikpak AR0042003Ambler River Metamorphic7250 Da Ambler sequence Devonian Interlayered white to medium gray weathering metarhyolite, dark green weathering metabasite, pale gray weathering marble, and brown to dark gray weathering calcareous, pelitic and carbonaceous schist exposed in two areas in the Schist belt. "MetarhyoliteOne conodont of Devonian age U-Pb zircon ages from metarhyolite layers 378-386 Ma, bimodal igneous zircon population about 378 and 405 Ma from Arctic deposit. AR0042004Ambler River Metamorphic7260 OPc Older carbonate rocks of the Central belt Middle Ordovician to Proterozoic? Dolostone, metalimestone, marble and subordinate quartzose metasedimentary rocks, carbonate conglomerate, and metabasite exposed in the northeastern Baird Mountains quadrangle, central Survey Pass quadrangle, and along the Dalton Highway in the Wiseman aConodonts, stromatolites, protoconodonts, chancellorid sclerites, hyolithids, and steinkerns of monoplacophoran mollusks, acrotretid brachiopods,agnostid arthropods, graptolites AR0042015Ambler River Metamorphic7740 Pzbq Black quartzite Paleozoic? Black weathering, fine to medium grained black metaquartzite exposed in the western Schist belt along the contact between units Dsq and DPsc. May contain small amounts of mica and show segregation of quartz and graphite in layers parallel to foliation. AR0042065Ambler River Metamorphic8602 Dsq Quartz-mica schist Devonian Gray, dark gray, or brownish-gray weathering, dominantly pelitic or semipelitic schist that constitutes a major unit along the length of the Schist belt. Outcrops vary from blocky and resistant (quartz-rich varieties) to platy and less resistant (mica-r Youngest detrital zircon population at one locality 370-360 Ma AR0042000Ambler River Metamorphic8602 PzZqs Quartz-rich metasedimentary rocks Paleozoic to Proterozoic? Relatively homogeneous assemblage dominated by light greenish-gray fine-grained quartz-rich schist, typically accompanied by minor layers of metaconglomerate, marble, and calcareous schist. Exposed in the southern Central belt in the western Survey PassConodont AR0042021Ambler River Metamorphic8603 DpCsc Calcareous schist, Schist belt Devonian to Proterozoic Light gray, brown and locally orange-weathering, lithologically heterogeneous mix of marble and carbonate-rich, quartz-rich, and mafic schist derived from metasedimentary and metaigneous protoliths, one of two major units that extends along the length ofGhosts of radiolarians, sponge spicules, bivalves, fine graphite laminae, stromatolites, conodonts AR0042001Ambler River Metamorphic8605 DpCsc_541Calcareous schist - albite-rich subunit, Schist belt Devonian to Proterozoic Light gray, brown and locally orange-weathering, lithologically heterogeneous mix of marble and carbonate-rich, quartz-rich, and mafic schist derived from metasedimentary and metaigneous protoliths, one of two major units that extends along the length ofGhosts of radiolarians, sponge spicules, bivalves, fine graphite laminae, stromatolites, conodonts AR0042063Ambler River Metamorphic8607 PzZcm Metasedimentary and metavolcanic rocks, undivided Paleozoic and Proterozoic? Heterogeneous assemblage of interlayered calcareous, mafic, and siliceous rocks exposed in the central Baird Mountains, Ambler River, and Wiseman quadrangles. This unit is part of the Central belt. Conodonts AR0042046Ambler River Metamorphic8655 PzZm Mafic schist Proterozoic? to Paleozoic? Dark green weathering foliated mafic schist exposed in one area on the boundary between the Ambler River and Survey Pass quadrangles. This unit is part of the Central belt. AR0042047Ambler River Metamorphic8661 pCam Metamorphic rocks of Mt. Angayukaqsraq Proterozoic Amphibolite, metaquartzite, calcareous schist, metapelite, and a few small bodies of metagranite and metagabbro, exposed in the northeastern Baird Mountains quadrangle around Mt. Angayukaqsraq, in the south central Baird Mountains quadrangle near the Kob 40Ar/39Ar - 680 Ma metamorphic age, overprinting event - 40Ar/39Ar age of 120 Ma AR0042013Ambler River Metamorphic9300 pCam_572 Metamorphic rocks of Mt. Angayukaqsraq, remetamorphosed Proterozoic Amphibolite, metaquartzite, calcareous schist, metapelite, and a few small bodies of metagranite and metagabbro, originally metamorphosed at amphibolite-facies rocks and overprinted by an albite epidote amphibolite facies event. Mafic outcrops in these 40Ar/39Ar - 680 Ma metamorphic age, overprinting event - 40Ar/39Ar age of 120 Ma AR0042068Ambler River Metamorphic9300 Qs Surficial sedimentary deposits, undivided Quaternary Frost-rived rubble on slopes and broad low ridges; glacially deposted sand, gravel, and boulders; fluvial gravel and sand; terrace deposits. BM0042040Baird Mountains Sedimentary100 1000 Ks Conglomerate, sandstone, and shale Cretaceous Conglomerate and finer grained sedimentary rocks that grade from massive, poorly stratified rocks rich in mafic intrusive and extrusive clasts at the base of the unit to a well-sorted sedimentary rock rich in quartz and metagraywacke clasts at the top ofSparse plant fossils of Early to Late Cretaceous age; Early Cretaceous? marine mollusks BM0042038Baird Mountains Sedimentary1990 MzDm Igneous and sedimentary rocks of the Maiyumerak Mountains Cretaceous? to Devonian Basalt, limestone, and two belts of melange exposed in the northwesternmost part of the map area. This unit is part of the Maiyumerak sequence. Conodonts and megafossils BM0042076Baird Mountains Tectonite 4951 JDk Rocks of the Kivivik Creek sequence Jurassic to Devonian Consists, in ascending order, of Devonian marine sedimentary rocks equivalent to unit Dmu, sandstone, conglomerate, and shale of the Endicott Group (Devonian and Mississippian), limestone and tuff (Mississippian), chert and phyllite (Carboniferous), and Conodonts, brachiopods and mollusks, foraminifers; radiolarian ghosts BM0042075Baird Mountains Metamorphic5001 KJm Melange Cretaceous to Jurassic Tectonic assemblage of meter to kilometer-scale fault slivers of pillow basalt, mafic schist, metagabbro, metalimestone, metachert, metagraywacke, phyllite, and rare serpentinite exposed in low hills in the south central and southwestern part of the map Radiolarians, conodonts BM0042092Baird Mountains Metamorphic5145 Pzp Phyllite Paleozoic? Phyllite, fine-grained schist, and phyllonite of the Central belt that underlie areas of poor exposure in the northeastern Baird Mountains quadrangle, western Ambler River quadrangle, and northwestern Chandalar quadrangle. Locally contains minor lenses BM0042030Baird Mountains Metamorphic5560 Pzpg Phyllite and graywacke Paleozoic? Dark gray to black phyllite and brown-weathering greywacke, sandstone, and mudstone exposed along the southern boundary of the schist belt. The unit varies in breadth along strike. In the Wiseman and Chandalar quadrangles, two subunits are recognized: BM0042007Baird Mountains Metamorphic5565 Mcp Carbonaceous chert and siliceous phyllite Mississippian Black carbonaceous metachert and siliceous phyllite exposed in a small area in the northwestern Baird Mountains quadrangle. Massive iron sulfide intervals with elevated silver and other metal values have been documented. conodonts, Devonian-Mississippian BM0042071Baird Mountains Metamorphic6200 MDe Endicott Group, undivided Mississippian and Devonian Shale and sandstone exposed in the northwest Baird Mountains quadrangle. Represents undifferentiated parts equivalent the Hunt Fork Shale (unit Dhf), the Noatak Sandstone (unit Dn) and the Mississippian Kayak Shale (part of unit Mkl). BM0042074Baird Mountains Sedimentary6300 Ml Carbonate rocks Mississippian Light- to medium-gray weathering, dark-gray metalimestone and dolostone with locally abundant layers and lenses of black chert; megafossils (mainly silicified) include corals and possible stromatolites exposed at one locality in the Nanielik antiform, noCorals, stromatolites, conodonts (latest Meramecian to early Chesterian), Meramecian-early Chesterian lithostrotionid corals BM0042027Baird Mountains Metamorphic6320 Mkl Kayak Shale of Endicott Group and Lisburne Group Mississippian Phyllite or slate, siltsone, sandstone, limestone, and chert in two small exposures in the northwestern Baird Mountains quadrangle and in a larger area in the Survey Pass quadrangle. Ostracodes, brachiopods, bryozoans, and echinoderm debris, conodonts, crinoid, bryozoan, and coralline debris, brachiopods, gastropods, sponge spicules, endothyrid foraminifers BM0042061Baird Mountains Metamorphic6328 Dn Noatak Sandstone Devonian Consists of metasandstone and metasiltstone with subordinate interlayers of green, gray, and maroon phyllite and local ironstone concretions. Semischistose textures and minerals indicative of lower greenschist facies metamorphism occur locally, but origiLate Devonian (some Famennian)conodonts, brachiopods, echinoderms, gastropods, pelecypods, plant debris, and trace fossils BM0042056Baird Mountains Metamorphic6900 MDk Kanuyut Conglomerate Lower Mississippian? and Upper DevonianQuartzite, pebbly quartzite, conglomerte, and minor siltstone. Exposed in a few small areas of northwestern Baird Mountains quadrangle, northeastern Ambler River quadrangle, and widely distributed in northern Survey Pass quadrangle. Semischistose and myEchinoderm debris, brachiopods, mollusks, cephalopods, and plant fragments BM0042028Baird Mountains Metamorphic6915 Dhf Hunt Fork Shale Late Devonian Dark gray to black phyllite and lesser gray-green phyllite with thin layers of siliceous or calcareous metasiltstone, lithic wacke, metasandstone, and minor layers of fossiliferous metalimestone exposed along the length of the northern boundary of the maBrachiopods (late Frasnian to early Fammenian), mollusks, echinoderms; Middle to Late Devonian conodonts BM0042018Baird Mountains Metamorphic6925 Dmu Metasedimentary and lesser metaigneous rocks Middle and Late Devonian Heterogeneous expanses of calcareous, siliceous, and volcaniclastic metasedimentary rocks, with lesser metaigneous rocks, exposed along the length of the Central belt. Includes significant expanses of rocks mapped as Beaucoup Formation by some workers. TMegafossils and conodonts are Middle and early Late Devonian U-Pb zircon crystallization age of 393+/-2 Ma from subunit that contains felsic to intermediate volcanic rocks BM0042017Baird Mountains Metamorphic6927 Dl Metalimestone Devonian Metalimestone and lesser metasandstone, metasiltstone, phyllite, and minor conglomerate. Assigned in part to Beaucoup Formation by some workers. This unit is part of the Central belt. late Middle to early Late Devonian conodonts and megafossils (solitary and colonial corals, stromatoporoids, brachiopods, and mollusks) BM0042019Baird Mountains Metamorphic6951 Dmu_541 Metasedimentary and lesser metaigneous rocks, volcanic-rock bearing subunit Middle and Late Devonian Part of heterogeneous expanses of calcareous, siliceous, and volcaniclastic metasedimentary rocks, with lesser metaigneous rocks, exposed along the length of the Central belt, thought to be correlative with the Beaucoup Formation. This subunit containMegafossils and conodonts are Middle and early Late Devonian U-Pb zircon crystallization age of 393+/-2 Ma from a foliated felsic rock BM0042043Baird Mountains Metamorphic6973 DOb Baird Group Devonian to Ordovician Beige- to orange-weathering, laminated, partly argillaceous to silty metalimestone and light- to dark-gray, flaggy-bedded to massive metalimestone, marble, and dolostone. The unit hosts several mineral occurrences and metabasaltic rocks of unknown age tconodonts; corals and stromatoporoids BM0042069Baird Mountains Metamorphic6980 DOc Younger carbonate rocks of the Nanielik Antiform, Central belt and part of Northern Thrust Assemblages Middle Devonian to Ordovician Very light- to dark-gray- (locally orange-) weathering, gray to black, commonly massive dolostone and lesser metalimestone and marble exposed in the northeastern Baird Mountains quadrangle in the Nanielik antiform and in the northwestern Chandalar quadraConodonts, corals, stromatoporoids BM0042016Baird Mountains Metamorphic6980 MDer Eli River sequence Mississippian and Devonian Dolostone, limestone, argillaceous or sandy limestone, sandstone, and limestone and dolostone with chert. This unit is part of the Eli River sequence defined by Karl and others, 1989). Stromatoporoids, brachiopods; pelmatozoan, bryozoan, and coral fragments, foraminifers, and algae (possibly mid-Famennian); spiculitic limestone; conodonts BM0042070Baird Mountains Sedimentary6982 Pzm Marble Paleozoic White to gray (less commonly black), fine to coarsely crystalline, massive to platy marble and subordinate metalimestone and dolostone occurs discontinuously in all quadrangles within the map area. This unit is part of the Central belt. Conodonts, silicified two-hole crinoid columnals of late Early-early Middle Devonian (late Emsian-Eifelian) age; brachiopods; possible stromatoporoids; pelmatozoan; trilobites BM0042023Baird Mountains Metamorphic6983 Pzsg Mafic schist Paleozoic Green and greenish-gray schistose to massive irregularly-shaped bodies and lenses of mafic rocks in units Dsq and DPsc large enough to show at the scale of the map occur in the Survey Pass and Chandalar quadrangles. This unit is part of the Schist belt. BM0042006Baird Mountains Metamorphic7000 Dhf_101 Hunt Fork Shale - foliated exposures Late Devonian Dark gray to black phyllite and lesser gray-green phyllite with thin layers of siliceous or calcareous metasiltstone, lithic wacke, metasandstone, and minor layers of fossiliferous metalimestone exposed along the length of the northern boundary of the maBrachiopods (late Frasnian to early Fammenian), mollusks, echinoderms; Middle to Late Devonian conodonts; BM0042044Baird Mountains Metamorphic7225 Pzb Black phyllite and siliceous phyllite Paleozoic? Gray to dark gray carbonaceous phyllite, locally silica rich, exposed in the Central belt in the western Ambler River quadrangle. This unit is part of the Central belt. BM0042066Baird Mountains Metamorphic7235 OPc Older carbonate rocks of the Central belt Middle Ordovician to Proterozoic? Dolostone, metalimestone, marble and subordinate quartzose metasedimentary rocks, carbonate conglomerate, and metabasite exposed in the northeastern Baird Mountains quadrangle, central Survey Pass quadrangle, and along the Dalton Highway in the Wiseman aConodonts, stromatolites, protoconodonts, chancellorid sclerites, hyolithids, and steinkerns of monoplacophoran mollusks, acrotretid brachiopods,agnostid arthropods, graptolites BM0042015Baird Mountains Metamorphic7740 OpCc_541 Older carbonate rocks of the Central belt, restricted Middle Ordovician to Proterozoic? Dolostone, metalimestone, marble and subordinate quartzose metasedimentary rocks, carbonate conglomerate, and metabasite. Only exposures that contain the Ordovician part of unit OPc are included in this unit. Conodonts, stromatolites, protoconodonts, chancellorid sclerites, hyolithids, and steinkerns of monoplacophoran mollusks, acrotretid brachiopods,agnostid arthropods, graptolites BM0042042Baird Mountains Metamorphic7741 Dsq Quartz-mica schist Devonian Gray, dark gray, or brownish-gray weathering, dominantly pelitic or semipelitic schist that constitutes a major unit along the length of the Schist belt. Outcrops vary from blocky and resistant (quartz-rich varieties) to platy and less resistant (mica-r Youngest detrital zircon population at one locality 370-360 Ma BM0042000Baird Mountains Metamorphic8602 Pzbq Black quartzite Paleozoic? Black weathering, fine to medium grained black metaquartzite exposed in the western Schist belt along the contact between units Dsq and DPsc. May contain small amounts of mica and show segregation of quartz and graphite in layers parallel to foliation. BM0042065Baird Mountains Metamorphic8602 DpCsc Calcareous schist, Schist belt Devonian to Proterozoic Light gray, brown and locally orange-weathering, lithologically heterogeneous mix of marble and carbonate-rich, quartz-rich, and mafic schist derived from metasedimentary and metaigneous protoliths, one of two major units that extends along the length ofGhosts of radiolarians, sponge spicules, bivalves, fine graphite laminae, stromatolites, conodonts BM0042001Baird Mountains Metamorphic8605 DpCsc_541Calcareous schist - albite-rich subunit, Schist belt Devonian to Proterozoic Light gray, brown and locally orange-weathering, lithologically heterogeneous mix of marble and carbonate-rich, quartz-rich, and mafic schist derived from metasedimentary and metaigneous protoliths, one of two major units that extends along the length ofGhosts of radiolarians, sponge spicules, bivalves, fine graphite laminae, stromatolites, conodonts BM0042063Baird Mountains Metamorphic8607 PzZcm Metasedimentary and metavolcanic rocks, undivided Paleozoic and Proterozoic? Heterogeneous assemblage of interlayered calcareous, mafic, and siliceous rocks exposed in the central Baird Mountains, Ambler River, and Wiseman quadrangles. This unit is part of the Central belt. Conodonts BM0042046Baird Mountains Metamorphic8655 PzZg Granitic rocks Paleozoic to Proterozoic? Pale gray-green, massive to gneissic granitic to dioritic orthogneiss exposed in the Schist belt in the southern Baird Mountains quadrangle. No direct age control; may be correlative with Pg. BM0042067Baird Mountains Metamorphic9045 pCg Granitic orthogneiss Paleozoic Metagranitic rocks of several Proterozoic ages exposed in southern Baird Mountains and western Wiseman quadrangles. U-Pb zircon ages: southern Baird Mtns quad - 705+/-35 Ma; Ernie Lake pluton - 971+/-5 Ma; Mt. Angayukaqsraq - 750 +/- 6 Ma BM0042011Baird Mountains Metamorphic9060 pCam Metamorphic rocks of Mt. Angayukaqsraq Proterozoic Amphibolite, metaquartzite, calcareous schist, metapelite, and a few small bodies of metagranite and metagabbro, exposed in the northeastern Baird Mountains quadrangle around Mt. Angayukaqsraq, in the south central Baird Mountains quadrangle near the Kob 40Ar/39Ar - 680 Ma metamorphic age, overprinting event - 40Ar/39Ar age of 120 Ma BM0042013Baird Mountains Metamorphic9300 pCam_572 Metamorphic rocks of Mt. Angayukaqsraq, remetamorphosed Proterozoic Amphibolite, metaquartzite, calcareous schist, metapelite, and a few small bodies of metagranite and metagabbro, originally metamorphosed at amphibolite-facies rocks and overprinted by an albite epidote amphibolite facies event. Mafic outcrops in these 40Ar/39Ar - 680 Ma metamorphic age, overprinting event - 40Ar/39Ar age of 120 Ma BM0042068Baird Mountains Metamorphic9300 Qs Surficial sedimentary deposits, undivided Quaternary Frost-rived rubble on slopes and broad low ridges; glacially deposted sand, gravel, and boulders; fluvial gravel and sand; terrace deposits. BT0052040Bettles Sedimentary100 1000 Ks Conglomerate, sandstone, and shale Cretaceous Conglomerate and finer grained sedimentary rocks that grade from massive, poorly stratified rocks rich in mafic intrusive and extrusive clasts at the base of the unit to a well-sorted sedimentary rock rich in quartz and metagraywacke clasts at the top ofSparse plant fossils of Early to Late Cretaceous age; Early Cretaceous? marine mollusks BT0052038Bettles Sedimentary1990 Ks Conglomerate, sandstone, and shale Cretaceous Conglomerate and finer grained sedimentary rocks that grade from massive, poorly stratified rocks rich in mafic intrusive and extrusive clasts at the base of the unit to a well-sorted sedimentary rock rich in quartz and metagraywacke clasts at the top ofSparse plant fossils of Early to Late Cretaceous age; Early Cretaceous? marine mollusks BT0052038Bettles Sedimentary1990 Kvg Volcanic-clast graywacke and mudstone Cretaceous Fine grained to conglomeratic greywacke and fine-grained laminated mudstone exposed along the south-central boundary of the map. Mudstone is locally tuffaceous. Clasts are predominantly intermediate and mafic volcanic and intrusive rocks and chert with Marine mollusks of Late Early Cretaceous (Albian) age BT0052091Bettles Sedimentary2180 Kg Granitic rocks Cretaceous Granite, quartz monzonite, and granodiorite of the northern Ruby terrane, exposed along the southern boundary of the Chandalar quadrangle. K-Ar dates from south of map area are 96-112 Ma BT0052037Bettles Igneous 2492 JDab Mafic metavolcanic and metaintrusive rocks, metachert, metalimestone, and amphibolite of the Angayucham terrane Early Jurassic to Devonian Metamorphosed pillow basalt, hyaloclastic breccia, basaltic tuff, diabase, microgabbro, radiolarian and tuffaceous chert, minor metalimestone, and rare mafic schist in an imbricate package exposed along the southern boundary of the map area. Commonly, meRadiolarians, conodonts, megafossils, foraminifers, bryozoans, brachiopods BT0052009Bettles Metamorphic5133 DpCm Metamorphic rocks, Mosquito terrane Devonian to Proterozoic? Pelitic schist, metabasite, minor felsic orthogneiss and meta-ultramafic rock exposed in two small areas along the Kobuk fault zone in the northeast Bettles and southwest Chandalar quadrangles. The rocks exhibit amphibolite-facies metamorphic assemblage 54.8 +/- 1.3 Ma white mica cooling age BT0052008Bettles Metamorphic8852 Qs Surficial sedimentary deposits, undivided Quaternary Frost-rived rubble on slopes and broad low ridges; glacially deposted sand, gravel, and boulders; fluvial gravel and sand; terrace deposits. CH0042040Chandalar Sedimentary100 1000 QTb Basalt Quaternary? or Tertiary? Flat-lying, vesicular olivine basalt flows exposed in the southeast part of the Chandalar quadrangle. Thought to be about 300 meters thick. CH0042039Chandalar Igneous 350 3500 Ks Conglomerate, sandstone, and shale Cretaceous Conglomerate and finer grained sedimentary rocks that grade from massive, poorly stratified rocks rich in mafic intrusive and extrusive clasts at the base of the unit to a well-sorted sedimentary rock rich in quartz and metagraywacke clasts at the top ofSparse plant fossils of Early to Late Cretaceous age; Early Cretaceous? marine mollusks CH0042038Chandalar Sedimentary1990 Kg Granitic rocks Cretaceous Granite, quartz monzonite, and granodiorite of the northern Ruby terrane, exposed along the southern boundary of the Chandalar quadrangle. K-Ar dates from south of map area are 96-112 Ma CH0042037Chandalar Igneous 2492 Km Migmatite Cretaceous Intercalated granitic rocks, biotite schist, and hornblende hornfels; pyroxene hornfels and granitic dikes, associated with Cretaceous granitic rocks. All exposed in the northern Ruby terrane, along the southern margin of the Chandalar quadrangle. Inc CH0042036Chandalar Metamorphic2610 Khs Rocks of the Hammond River shear zone Cretaceous? Heterogeneous mix of finely laminated, mostly mylonitic lithologies derived in part from adjacent units exposed in the eastern Wiseman and western Chandalar quadrangles. Unit is recessive, poorly exposed, and includes large (up to 0.5 km across) bodies CH0042022Chandalar Metamorphic2650 TrCs Sedimentary rocks Triassic to Carboniferous Quartzite, phyllite, siltstone, conglomerate, shale, sandstone, limestone, argillaceous limestone, dolomitic limestone, and cherty dolostone. Occurs in the Mount Doonerak area in northeastern Wiseman and northwestern Chandalar quadrangles, where it is iConodonts; foraminifers; crinoidal packstone; burrows and trace fossils; brachiopods Wolfcampian age CH0042026Chandalar Sedimentary5004 JDab Mafic metavolcanic and metaintrusive rocks, metachert, metalimestone, and amphibolite of the Angayucham terrane Early Jurassic to Devonian Metamorphosed pillow basalt, hyaloclastic breccia, basaltic tuff, diabase, microgabbro, radiolarian and tuffaceous chert, minor metalimestone, and rare mafic schist in an imbricate package exposed along the southern boundary of the map area. Commonly, meRadiolarians, conodonts, megafossils, foraminifers, bryozoans, brachiopods CH0042009Chandalar Metamorphic5133 Pzp Phyllite Paleozoic? Phyllite, fine-grained schist, and phyllonite of the Central belt that underlie areas of poor exposure in the northeastern Baird Mountains quadrangle, western Ambler River quadrangle, and northwestern Chandalar quadrangle. Locally contains minor lenses CH0042030Chandalar Metamorphic5560 Pzpg Phyllite and graywacke Paleozoic? Dark gray to black phyllite and brown-weathering greywacke, sandstone, and mudstone exposed along the southern boundary of the schist belt. The unit varies in breadth along strike. In the Wiseman and Chandalar quadrangles, two subunits are recognized: CH0042007Chandalar Metamorphic5565 SCvs Volcanic and sedimentary rocks Silurian to Cambrian Volcanic rocks, volcaniclastic rocks, and clastic sedimentary rocks exposed in the core of the Doonerak antiform, northeast Wiseman quadrangle. The unit can be divided into at least two lithologic sequences, one dominated by volcanic rocks, the other byMicrofossils, brachiopods, trilobites, graptolites, conodonts K-Ar and Ar-Ar ages of dikes 373-388 Ma and 478 Ma CH0042057Chandalar Sedimentary6720 Pzj Metasedimentary rocks of Jesse Mountain Paleozoic Generally fine grained, phyllitic to schistose, gray-weathering meta-argillite, black-weathering metaquartzite, marble, and brown weathering impure marble, exposed in a single area in the eastern Wiseman quadrangle. This unit is part of the Central belConodonts; brachiopods; coral fragments CH0042032Chandalar Metamorphic6850 Dhf Hunt Fork Shale Late Devonian Dark gray to black phyllite and lesser gray-green phyllite with thin layers of siliceous or calcareous metasiltstone, lithic wacke, metasandstone, and minor layers of fossiliferous metalimestone exposed along the length of the northern boundary of the maBrachiopods (late Frasnian to early Fammenian), mollusks, echinoderms; Middle to Late Devonian conodonts; CH0042018Chandalar Metamorphic6925 Pzw Metasedimentary rocks Paleozoic Weakly metamorphosed metasandstone, meta-argillite, phyllite, conglomerate, and rare marble exposed in two belts on the Wiseman/Chandalar quadangle boundary. This subunit, the northern belt, is composed of metasandstone and argillite, and contains abund Detrital white mica -Ordovician 40Ar/39Ar cooling age CH0042053Chandalar Metamorphic6927 Pzw_572 Metasedimentary rocks Paleozoic Weakly metamorphosed metasandstone, meta-argillite, phyllite, conglomerate, and rare marble exposed in two belts on the Wiseman/Chandalar quadangle boundary. This subunit, the southern of the two belts, is composed of phyllite, metasandstone with volcaConodonts, bryozoans, corals CH0042055Chandalar Metamorphic6927 Dmu Metasedimentary and lesser metaigneous rocks Middle and Late Devonian Heterogeneous expanses of calcareous, siliceous, and volcaniclastic metasedimentary rocks, with lesser metaigneous rocks, exposed along the length of the Central belt. Includes significant expanses of rocks mapped as Beaucoup Formation by some workers. TMegafossils and conodonts are Middle and early Late Devonian U-Pb zircon crystallization age of 393+/-2 Ma from subunit that contains felsic to intermediate volcanic rocks CH0042017Chandalar Metamorphic6927 Dl Metalimestone Devonian Metalimestone and lesser metasandstone, metasiltstone, phyllite, and minor conglomerate. Assigned in part to Beaucoup Formation by some workers. This unit is part of the Central belt. late Middle to early Late Devonian conodonts and megafossils (solitary and colonial corals, stromatoporoids, brachiopods, and mollusks) CH0042019Chandalar Metamorphic6951 Dmu_541 Metasedimentary and lesser metaigneous rocks, volcanic-rock bearing subunit Middle and Late Devonian Part of heterogeneous expanses of calcareous, siliceous, and volcaniclastic metasedimentary rocks, with lesser metaigneous rocks, exposed along the length of the Central belt, thought to be correlative with the Beaucoup Formation. This subunit containMegafossils and conodonts are Middle and early Late Devonian U-Pb zircon crystallization age of 393+/-2 Ma from a foliated felsic rock CH0042043Chandalar Metamorphic6973 DOc Younger carbonate rocks of the Nanielik Antiform, Central belt and part of Northern Thrust Assemblages Middle Devonian to Ordovician Very light- to dark-gray- (locally orange-) weathering, gray to black, commonly massive dolostone and lesser metalimestone and marble exposed in the northeastern Baird Mountains quadrangle in the Nanielik antiform and in the northwestern Chandalar quadraConodonts, corals, stromatoporoids CH0042016Chandalar Metamorphic6980 Pzm Marble Paleozoic White to gray (less commonly black), fine to coarsely crystalline, massive to platy marble and subordinate metalimestone and dolostone occurs discontinuously in all quadrangles within the map area. This unit is part of the Central belt. Conodonts, silicified two-hole crinoid columnals of late Early-early Middle Devonian (late Emsian-Eifelian) age; brachiopods; possible stromatoporoids; pelmatozoan; trilobites CH0042023Chandalar Metamorphic6983 Pzsg Mafic schist Paleozoic Green and greenish-gray schistose to massive irregularly-shaped bodies and lenses of mafic rocks in units Dsq and DPsc large enough to show at the scale of the map occur in the Survey Pass and Chandalar quadrangles. This unit is part of the Schist belt. CH0042006Chandalar Metamorphic7000 Dps_101 Wacke and lesser amounts of shale - schistose Devonian Schistose varieties of gray-green lithic wacke, lesser brown quartz wacke, and black shale and silty shale exposed in the eastern map area. This unit is part of the Phyllite belt. CH0042083Chandalar Metamorphic7200 Dhf_101 Hunt Fork Shale - foliated exposures Late Devonian Dark gray to black phyllite and lesser gray-green phyllite with thin layers of siliceous or calcareous metasiltstone, lithic wacke, metasandstone, and minor layers of fossiliferous metalimestone exposed along the length of the northern boundary of the maBrachiopods (late Frasnian to early Fammenian), mollusks, echinoderms; Middle to Late Devonian conodonts; CH0042044Chandalar Metamorphic7225 Dg Granitic orthogneiss Devonian Tan to gray weathering, equigranular to porphyroblastic, fine to coarse grained metagranitic bodies ranging in size from less than a kilometer to over 20 kms across, found in both the Schist and Central belts. Generally granitic in composition and made U-Pb zircon dates for orthogneiss 390-396 Ma; 375-395 Ma for orthogneiss at Mt. Igikpak CH0042003Chandalar Metamorphic7250 OpCc Older carbonate rocks of the Central belt Middle Ordovician to Proterozoic? Dolostone, metalimestone, marble and subordinate quartzose metasedimentary rocks, carbonate conglomerate, and metabasite exposed in the northeastern Baird Mountains quadrangle, central Survey Pass quadrangle, and along the Dalton Highway in the Wiseman aConodonts, stromatolites, protoconodonts, chancellorid sclerites, hyolithids, and steinkerns of monoplacophoran mollusks, acrotretid brachiopods,agnostid arthropods, graptolites CH0042015Chandalar Metamorphic7740 OpCc_541 Older carbonate rocks of the Central belt, restricted Middle Ordovician to Proterozoic? Dolostone, metalimestone, marble and subordinate quartzose metasedimentary rocks, carbonate conglomerate, and metabasite. Only exposures that contain the Ordovician part of unit OPc are included in this unit. Conodonts, stromatolites, protoconodonts, chancellorid sclerites, hyolithids, and steinkerns of monoplacophoran mollusks, acrotretid brachiopods,agnostid arthropods, graptolites CH0042042Chandalar Metamorphic7741 PzZbs Biotite schist Paleozoic to Proterozoic? Quartz-albite-oligoclase-biotite schist with staurolite and andalusite exposed in the southeastern Chandalar quadrangle, adjacent to rocks of the Schist belt. Age of metamorphism not known. This unit is part of the Ruby terrane. CH0042034Chandalar Metamorphic8601 Dsq Quartz-mica schist Devonian Gray, dark gray, or brownish-gray weathering, dominantly pelitic or semipelitic schist that constitutes a major unit along the length of the Schist belt. Outcrops vary from blocky and resistant (quartz-rich varieties) to platy and less resistant (mica-r Youngest detrital zircon population at one locality 370-360 Ma CH0042000Chandalar Metamorphic8602 PzZqs Quartz-rich metasedimentary rocks Paleozoic to Proterozoic? Relatively homogeneous assemblage dominated by light greenish-gray fine-grained quartz-rich schist, typically accompanied by minor layers of metaconglomerate, marble, and calcareous schist. Exposed in the southern Central belt in the western Survey PassConodont CH0042021Chandalar Metamorphic8603 DpCsc Calcareous schist, Schist belt Devonian to Proterozoic Light gray, brown and locally orange-weathering, lithologically heterogeneous mix of marble and carbonate-rich, quartz-rich, and mafic schist derived from metasedimentary and metaigneous protoliths, one of two major units that extends along the length ofGhosts of radiolarians, sponge spicules, bivalves, fine graphite laminae, stromatolites, conodonts CH0042001Chandalar Metamorphic8605 DpCsc_101Calcareous schist - metachert and conglomerate subunit, Schist belt Devonian to Proterozoic Light gray, brown and locally orange-weathering, lithologically heterogeneous mix of marble and carbonate-rich, quartz-rich, and mafic schist derived from metasedimentary and metaigneous protoliths, one of two major units that extends along the length ofGhosts of radiolarians, sponge spicules, bivalves, fine graphite laminae, stromatolites, conodonts CH0042041Chandalar Metamorphic8608 DpCm Metamorphic rocks, Mosquito terrane Devonian to Proterozoic? Pelitic schist, metabasite, minor felsic orthogneiss and meta-ultramafic rock exposed in two small areas along the Kobuk fault zone in the northeast Bettles and southwest Chandalar quadrangles. The rocks exhibit amphibolite-facies metamorphic assemblage 54.8 +/- 1.3 Ma white mica cooling age CH0042008Chandalar Metamorphic8852 PzZsr Ruby schist Paleozoic to Proterozoic? Biotite-bearing pelitic schist with subordinate metaquartzite, exposed in the southern Wiseman quadrangle. Equivalent to schists of the Ruby geanticline, south of the map area, where the earliest documented metamorphic event to affect the schists was bl CH0042035Chandalar Metamorphic9325 Qs Surficial sedimentary deposits, undivided Quaternary Frost-rived rubble on slopes and broad low ridges; glacially deposted sand, gravel, and boulders; fluvial gravel and sand; terrace deposits. CS0042040Christian Sedimentary100 1000 Kg Granitic rocks Cretaceous Granite, quartz monzonite, and granodiorite of the northern Ruby terrane, exposed along the southern boundary of the Chandalar quadrangle. K-Ar dates from south of map area are 96-112 Ma CS0042037Christian Igneous 2492 JDab Mafic metavolcanic and metaintrusive rocks, metachert, metalimestone, and amphibolite of the Angayucham terrane Early Jurassic to Devonian Metamorphosed pillow basalt, hyaloclastic breccia, basaltic tuff, diabase, microgabbro, radiolarian and tuffaceous chert, minor metalimestone, and rare mafic schist in an imbricate package exposed along the southern boundary of the map area. Commonly, meRadiolarians, conodonts, megafossils, foraminifers, bryozoans, brachiopods CS0042009Christian Metamorphic5133 Dps Wacke and lesser amounts of shale Devonian Dominantly gray-green lithic wacke, lesser brown quartz wacke, and black shale and silty shale exposed in the eastern map area. Wackes are fine- to medium-grained and thin to medium-bedded. Black shale forms up to 50 percent of the unit and occurs in l CS0042083Christian Sedimentary6900 Dmu Metasedimentary and lesser metaigneous rocks Middle and Late Devonian Heterogeneous expanses of calcareous, siliceous, and volcaniclastic metasedimentary rocks, with lesser metaigneous rocks, exposed along the length of the Central belt. Includes significant expanses of rocks mapped as Beaucoup Formation by some workers. TMegafossils and conodonts are Middle and early Late Devonian U-Pb zircon crystallization age of 393+/-2 Ma from subunit that contains felsic to intermediate volcanic rocks CS0042017Christian Metamorphic6927 Dl Metalimestone Devonian Metalimestone and lesser metasandstone, metasiltstone, phyllite, and minor conglomerate. Assigned in part to Beaucoup Formation by some workers. This unit is part of the Central belt. late Middle to early Late Devonian conodonts and megafossils (solitary and colonial corals, stromatoporoids, brachiopods, and mollusks) CS0042019Christian Metamorphic6951 Dmu_541 Metasedimentary and lesser metaigneous rocks, volcanic-rock bearing subunit Middle and Late Devonian Part of heterogeneous expanses of calcareous, siliceous, and volcaniclastic metasedimentary rocks, with lesser metaigneous rocks, exposed along the length of the Central belt, thought to be correlative with the Beaucoup Formation. This subunit containMegafossils and conodonts are Middle and early Late Devonian U-Pb zircon crystallization age of 393+/-2 Ma from a foliated felsic rock CS0042043Christian Metamorphic6973 Pzm Marble Paleozoic White to gray (less commonly black), fine to coarsely crystalline, massive to platy marble and subordinate metalimestone and dolostone occurs discontinuously in all quadrangles within the map area. This unit is part of the Central belt. Conodonts, silicified two-hole crinoid columnals of late Early-early Middle Devonian (late Emsian-Eifelian) age; brachiopods; possible stromatoporoids; pelmatozoan; trilobites CS0042023Christian Metamorphic6983 Dps_101 Wacke and lesser amounts of shale - schistose Devonian Schistose varieties of gray-green lithic wacke, lesser brown quartz wacke, and black shale and silty shale exposed in the eastern map area. This unit is part of the Phyllite belt. CS0042083Christian Metamorphic7200 Dhf_101 Hunt Fork Shale - foliated exposures Late Devonian Dark gray to black phyllite and lesser gray-green phyllite with thin layers of siliceous or calcareous metasiltstone, lithic wacke, metasandstone, and minor layers of fossiliferous metalimestone exposed along the length of the northern boundary of the maBrachiopods (late Frasnian to early Fammenian), mollusks, echinoderms; Middle to Late Devonian conodonts; CS0042044Christian Metamorphic7225 PzZbs Biotite schist Paleozoic to Proterozoic? Quartz-albite-oligoclase-biotite schist with staurolite and andalusite exposed in the southeastern Chandalar quadrangle, adjacent to rocks of the Schist belt. Age of metamorphism not known. This unit is part of the Ruby terrane. CS0042034Christian Metamorphic8601 Dsq Quartz-mica schist Devonian Gray, dark gray, or brownish-gray weathering, dominantly pelitic or semipelitic schist that constitutes a major unit along the length of the Schist belt. Outcrops vary from blocky and resistant (quartz-rich varieties) to platy and less resistant (mica-r Youngest detrital zircon population at one locality 370-360 Ma CS0042000Christian Metamorphic8602 Qs Surficial sedimentary deposits, undivided Quaternary Frost-rived rubble on slopes and broad low ridges; glacially deposted sand, gravel, and boulders; fluvial gravel and sand; terrace deposits. HU0042040Hughes Sedimentary100 1000 Ks Conglomerate, sandstone, and shale Cretaceous Conglomerate and finer grained sedimentary rocks that grade from massive, poorly stratified rocks rich in mafic intrusive and extrusive clasts at the base of the unit to a well-sorted sedimentary rock rich in quartz and metagraywacke clasts at the top ofSparse plant fossils of Early to Late Cretaceous age; Early Cretaceous? marine mollusks HU0042038Hughes Sedimentary1990 Kvg Volcanic-clast graywacke and mudstone Cretaceous Fine grained to conglomeratic greywacke and fine-grained laminated mudstone exposed along the south-central boundary of the map. Mudstone is locally tuffaceous. Clasts are predominantly intermediate and mafic volcanic and intrusive rocks and chert with Marine mollusks of Late Early Cretaceous (Albian) age HU0042091Hughes Sedimentary2180 JDab Mafic metavolcanic and metaintrusive rocks, metachert, metalimestone, and amphibolite of the Angayucham terrane Early Jurassic to Devonian Metamorphosed pillow basalt, hyaloclastic breccia, basaltic tuff, diabase, microgabbro, radiolarian and tuffaceous chert, minor metalimestone, and rare mafic schist in an imbricate package exposed along the southern boundary of the map area. Commonly, meRadiolarians, conodonts, megafossils, foraminifers, bryozoans, brachiopods HU0042009Hughes Metamorphic5133 KJm Melange Cretaceous to Jurassic Tectonic assemblage of meter to kilometer-scale fault slivers of pillow basalt, mafic schist, metagabbro, metalimestone, metachert, metagraywacke, phyllite, and rare serpentinite exposed in low hills in the south central and southwestern part of the map Radiolarians, conodonts HU0042092Hughes Metamorphic5145 Pzpg Phyllite and graywacke Paleozoic? Dark gray to black phyllite and brown-weathering greywacke, sandstone, and mudstone exposed along the southern boundary of the schist belt. The unit varies in breadth along strike. In the Wiseman and Chandalar quadrangles, two subunits are recognized: HU0042007Hughes Metamorphic5565 Qs Surficial sedimentary deposits, undivided Quaternary Frost-rived rubble on slopes and broad low ridges; glacially deposted sand, gravel, and boulders; fluvial gravel and sand; terrace deposits. SE0052040Selawik Sedimentary100 1000 Ks Conglomerate, sandstone, and shale Cretaceous Conglomerate and finer grained sedimentary rocks that grade from massive, poorly stratified rocks rich in mafic intrusive and extrusive clasts at the base of the unit to a well-sorted sedimentary rock rich in quartz and metagraywacke clasts at the top ofSparse plant fossils of Early to Late Cretaceous age; Early Cretaceous? marine mollusks SE0052038Selawik Sedimentary1990 Pzm Marble Paleozoic White to gray (less commonly black), fine to coarsely crystalline, massive to platy marble and subordinate metalimestone and dolostone occurs discontinuously in all quadrangles within the map area. This unit is part of the Central belt. Conodonts, silicified two-hole crinoid columnals of late Early-early Middle Devonian (late Emsian-Eifelian) age; brachiopods; possible stromatoporoids; pelmatozoan; trilobites SE0052023Selawik Metamorphic6983 Pzsg Mafic schist Paleozoic Green and greenish-gray schistose to massive irregularly-shaped bodies and lenses of mafic rocks in units Dsq and DPsc large enough to show at the scale of the map occur in the Survey Pass and Chandalar quadrangles. This unit is part of the Schist belt. SE0052006Selawik Metamorphic7000 Dsq Quartz-mica schist Devonian Gray, dark gray, or brownish-gray weathering, dominantly pelitic or semipelitic schist that constitutes a major unit along the length of the Schist belt. Outcrops vary from blocky and resistant (quartz-rich varieties) to platy and less resistant (mica-r Youngest detrital zircon population at one locality 370-360 Ma SE0052000Selawik Metamorphic8602 DpCsc Calcareous schist, Schist belt Devonian to Proterozoic Light gray, brown and locally orange-weathering, lithologically heterogeneous mix of marble and carbonate-rich, quartz-rich, and mafic schist derived from metasedimentary and metaigneous protoliths, one of two major units that extends along the length ofGhosts of radiolarians, sponge spicules, bivalves, fine graphite laminae, stromatolites, conodonts SE0052001Selawik Metamorphic8605 PzZcm Metasedimentary and metavolcanic rocks, undivided Paleozoic and Proterozoic? Heterogeneous assemblage of interlayered calcareous, mafic, and siliceous rocks exposed in the central Baird Mountains, Ambler River, and Wiseman quadrangles. This unit is part of the Central belt. Conodonts SE0052046Selawik Metamorphic8655 Qs Surficial sedimentary deposits, undivided Quaternary Frost-rived rubble on slopes and broad low ridges; glacially deposted sand, gravel, and boulders; fluvial gravel and sand; terrace deposits. SH0052040Shungnak Sedimentary100 1000 Ks Conglomerate, sandstone, and shale Cretaceous Conglomerate and finer grained sedimentary rocks that grade from massive, poorly stratified rocks rich in mafic intrusive and extrusive clasts at the base of the unit to a well-sorted sedimentary rock rich in quartz and metagraywacke clasts at the top ofSparse plant fossils of Early to Late Cretaceous age; Early Cretaceous? marine mollusks SH0052038Shungnak Sedimentary1990 Ks Conglomerate, sandstone, and shale Cretaceous Conglomerate and finer grained sedimentary rocks that grade from massive, poorly stratified rocks rich in mafic intrusive and extrusive clasts at the base of the unit to a well-sorted sedimentary rock rich in quartz and metagraywacke clasts at the top ofSparse plant fossils of Early to Late Cretaceous age; Early Cretaceous? marine mollusks SH0052038Shungnak Sedimentary1990 Kvg Volcanic-clast graywacke and mudstone Cretaceous Fine grained to conglomeratic greywacke and fine-grained laminated mudstone exposed along the south-central boundary of the map. Mudstone is locally tuffaceous. Clasts are predominantly intermediate and mafic volcanic and intrusive rocks and chert with Marine mollusks of Late Early Cretaceous (Albian) age SH0052091Shungnak Sedimentary2180 MzPzs Serpentinite Mesozoic? to Paleozoic? Greenish-gray, yellowish-green, olive green or greenish black serpentinite, minor basaltic rocks, harzburgite tectonite, and nephrite jade exposed in the southern Ambler River and adjacent Shungnak quadrangles. In the Cosmos Hills fault-bounded serpentin SH0052073Shungnak Metamorphic3498 JDab Mafic metavolcanic and metaintrusive rocks, metachert, metalimestone, and amphibolite of the Angayucham terrane Early Jurassic to Devonian Metamorphosed pillow basalt, hyaloclastic breccia, basaltic tuff, diabase, microgabbro, radiolarian and tuffaceous chert, minor metalimestone, and rare mafic schist in an imbricate package exposed along the southern boundary of the map area. Commonly, meRadiolarians, conodonts, megafossils, foraminifers, bryozoans, brachiopods SH0052009Shungnak Metamorphic5133 JDab Mafic metavolcanic and metaintrusive rocks, metachert, metalimestone, and amphibolite of the Angayucham terrane Early Jurassic to Devonian Metamorphosed pillow basalt, hyaloclastic breccia, basaltic tuff, diabase, microgabbro, radiolarian and tuffaceous chert, minor metalimestone, and rare mafic schist in an imbricate package exposed along the southern boundary of the map area. Commonly, meRadiolarians, conodonts, megafossils, foraminifers, bryozoans, brachiopods SH0052009Shungnak Metamorphic5133 KJm Melange Cretaceous to Jurassic Tectonic assemblage of meter to kilometer-scale fault slivers of pillow basalt, mafic schist, metagabbro, metalimestone, metachert, metagraywacke, phyllite, and rare serpentinite exposed in low hills in the south central and southwestern part of the map Radiolarians, conodonts SH0052092Shungnak Metamorphic5145 DSc Carbonate rocks of Cosmos Hills Devonian and Silurian Thin-bedded to massive dolostone, metalimestone, and marble, locally graphitic or phyllitic exposed in fault slices in the Cosmos Hills. Minor thin, micaceous layers interpreted as airfall tuffs, and some buff to reddish gray dolostones thought to be of Conodonts, brachiopods, gastropods, crinoids, tabulate and rugose corals, stromatoporoids SH0052084Shungnak Metamorphic6927 Dg Granitic orthogneiss Devonian Tan to gray weathering, equigranular to porphyroblastic, fine to coarse grained metagranitic bodies ranging in size from less than a kilometer to over 20 kms across, found in both the Schist and Central belts. Generally granitic in composition and made U-Pb zircon dates for orthogneiss 390-396 Ma; 375-395 Ma for orthogneiss at Mt. Igikpak SH0052003Shungnak Metamorphic7250 Dsq Quartz-mica schist Devonian Gray, dark gray, or brownish-gray weathering, dominantly pelitic or semipelitic schist that constitutes a major unit along the length of the Schist belt. Outcrops vary from blocky and resistant (quartz-rich varieties) to platy and less resistant (mica-r Youngest detrital zircon population at one locality 370-360 Ma SH0052000Shungnak Metamorphic8602 DpCsc Calcareous schist, Schist belt Devonian to Proterozoic Light gray, brown and locally orange-weathering, lithologically heterogeneous mix of marble and carbonate-rich, quartz-rich, and mafic schist derived from metasedimentary and metaigneous protoliths, one of two major units that extends along the length ofGhosts of radiolarians, sponge spicules, bivalves, fine graphite laminae, stromatolites, conodonts SH0052001Shungnak Metamorphic8605 Qs Surficial sedimentary deposits, undivided Quaternary Frost-rived rubble on slopes and broad low ridges; glacially deposted sand, gravel, and boulders; fluvial gravel and sand; terrace deposits. SP0042040Survey Pass Sedimentary100 1000 Ks Conglomerate, sandstone, and shale Cretaceous Conglomerate and finer grained sedimentary rocks that grade from massive, poorly stratified rocks rich in mafic intrusive and extrusive clasts at the base of the unit to a well-sorted sedimentary rock rich in quartz and metagraywacke clasts at the top ofSparse plant fossils of Early to Late Cretaceous age; Early Cretaceous? marine mollusks SP0042038Survey Pass Sedimentary1990 JDab Mafic metavolcanic and metaintrusive rocks, metachert, metalimestone, and amphibolite of the Angayucham terrane Early Jurassic to Devonian Metamorphosed pillow basalt, hyaloclastic breccia, basaltic tuff, diabase, microgabbro, radiolarian and tuffaceous chert, minor metalimestone, and rare mafic schist in an imbricate package exposed along the southern boundary of the map area. Commonly, meRadiolarians, conodonts, megafossils, foraminifers, bryozoans, brachiopods SP0042009Survey Pass Metamorphic5133 KJm Melange Cretaceous to Jurassic Tectonic assemblage of meter to kilometer-scale fault slivers of pillow basalt, mafic schist, metagabbro, metalimestone, metachert, metagraywacke, phyllite, and rare serpentinite exposed in low hills in the south central and southwestern part of the map Radiolarians, conodonts SP0042092Survey Pass Metamorphic5145 Pzpg Phyllite and graywacke Paleozoic? Dark gray to black phyllite and brown-weathering greywacke, sandstone, and mudstone exposed along the southern boundary of the schist belt. The unit varies in breadth along strike. In the Wiseman and Chandalar quadrangles, two subunits are recognized: SP0042007Survey Pass Metamorphic5565 Pzpg Phyllite and graywacke Paleozoic? Dark gray to black phyllite and brown-weathering greywacke, sandstone, and mudstone exposed along the southern boundary of the schist belt. The unit varies in breadth along strike. In the Wiseman and Chandalar quadrangles, two subunits are recognized: SP0042007Survey Pass Metamorphic5565 Mkl Kayak Shale of Endicott Group and Lisburne Group Mississippian Phyllite or slate, siltsone, sandstone, limestone, and chert in two small exposures in the northwestern Baird Mountains quadrangle and in a larger area in the Survey Pass quadrangle. Ostracodes, brachiopods, bryozoans, and echinoderm debris, conodonts, crinoid, bryozoan, and coralline debris, brachiopods, gastropods, sponge spicules, endothyrid foraminifers SP0042061Survey Pass Metamorphic6328 Pzbs Black metasedimentary rocks Paleozoic Dark gray to black phyllite and calcareous phyllite with dark gray to orange-weathering marble and dolostone layers up to 50 m thick, exposed in the northeastern Survey Pass and northwestern Wiseman quadrangles. This unit is part of the Central belt. Brachiopods - Middle Devonian or Frasnian (early Late Devonian) SP0042085Survey Pass Metamorphic6331 Mc Quartz-rich conglomerate Mississippian? Quartz- , chert-, quartzite-, and slate-clast conglomerate with minor thin layers of metasandstone and phyllite exposed in the Ambler River, Survey Pass, and Wiseman quadrangles. Quartz and chert clasts are most common; chert clasts are varicolored. Th SP0042077Survey Pass Metamorphic6360 Mu Metasedimentary rocks, undivided Mississippian Quartz conglomerate, quartzite, metasandstone, phyllite, shale, and metalimestone in the Ambler River, Survey Pass, and Wiseman quadrangles. Crinoids, brachiopods, corals, foraminifers, gastropods, molluscan and echinoderm debris, possible bryozoan, pelecypod, brachiopod, ostracode fragments, foraminifers SP0042062Survey Pass Metamorphic6365 Spl Black phyllite and metalimestone Silurian Black siliceous phyllite and metalimestone, metasandstone, metasiltstone, phyllite, and graphitic calcareous schist in the eastern Ambler River and western Survey Pass quandrangles. This unit is part of the Central belt. Originally mapped as the westerConodonts, graptolites, radiolarians; corals, gastropods, bryozoans, brachiopods, conularids, and orthocone cephalopods SP0042049Survey Pass Metamorphic6686 Dn Noatak Sandstone Devonian Consists of metasandstone and metasiltstone with subordinate interlayers of green, gray, and maroon phyllite and local ironstone concretions. Semischistose textures and minerals indicative of lower greenschist facies metamorphism occur locally, but origiLate Devonian (some Famennian)conodonts, brachiopods, echinoderms, gastropods, pelecypods, plant debris, and trace fossils SP0042056Survey Pass Metamorphic6900 MDk_101 Kanuyut Conglomerate and Noatak Sandstone Lower Mississippian? and Upper DevonianQuartzite, pebbly quartzite, conglomerate, and minor siltstone. This unit includes exposures where Kanayut has not been differentiated from Noatak Sandstone. Echinoderm debris, brachiopods, mollusks, cephalopods, and plant fragments SP0042089Survey Pass Metamorphic6914 MDk Kanuyut Conglomerate Lower Mississippian? and Upper DevonianQuartzite, pebbly quartzite, conglomerte, and minor siltstone. Exposed in a few small areas of northwestern Baird Mountains quadrangle, northeastern Ambler River quadrangle, and widely distributed in northern Survey Pass quadrangle. Semischistose and myEchinoderm debris, brachiopods, mollusks, cephalopods, and plant fragments SP0042028Survey Pass Metamorphic6915 Dhf Hunt Fork Shale Late Devonian Dark gray to black phyllite and lesser gray-green phyllite with thin layers of siliceous or calcareous metasiltstone, lithic wacke, metasandstone, and minor layers of fossiliferous metalimestone exposed along the length of the northern boundary of the maBrachiopods (late Frasnian to early Fammenian), mollusks, echinoderms; Middle to Late Devonian conodonts; SP0042018Survey Pass Metamorphic6925 Dmu Metasedimentary and lesser metaigneous rocks Middle and Late Devonian Heterogeneous expanses of calcareous, siliceous, and volcaniclastic metasedimentary rocks, with lesser metaigneous rocks, exposed along the length of the Central belt. Includes significant expanses of rocks mapped as Beaucoup Formation by some workers. TMegafossils and conodonts are Middle and early Late Devonian U-Pb zircon crystallization age of 393+/-2 Ma from subunit that contains felsic to intermediate volcanic rocks SP0042017Survey Pass Metamorphic6927 Dmu_542 Metasedimentary and lesser metaigneous rocks, calcareous, iron-rich components Middle and Late Devonian Part of heterogeneous expanses of calcareous, siliceous, and volcaniclastic metasedimentary rocks, with lesser metaigneous rocks, exposed along the length of the Central belt. This part of the unit contains a light brown, gray, and orange-weathering ferMegafossils and conodonts are Middle and early Late Devonian U-Pb zircon crystallization age of 393+/-2 Ma from subunit that contains felsic to intermediate volcanic rocks SP0042052Survey Pass Metamorphic6972 Dmu_541 Metasedimentary and lesser metaigneous rocks, volcanic-rock bearing subunit Middle and Late Devonian Part of heterogeneous expanses of calcareous, siliceous, and volcaniclastic metasedimentary rocks, with lesser metaigneous rocks, exposed along the length of the Central belt, thought to be correlative with the Beaucoup Formation. This subunit containMegafossils and conodonts are Middle and early Late Devonian U-Pb zircon crystallization age of 393+/-2 Ma from a foliated felsic rock SP0042043Survey Pass Metamorphic6973 Pzm Marble Paleozoic White to gray (less commonly black), fine to coarsely crystalline, massive to platy marble and subordinate metalimestone and dolostone occurs discontinuously in all quadrangles within the map area. This unit is part of the Central belt. Conodonts, silicified two-hole crinoid columnals of late Early-early Middle Devonian (late Emsian-Eifelian) age; brachiopods; possible stromatoporoids; pelmatozoan; trilobites SP0042023Survey Pass Metamorphic6983 Pzsg Mafic schist Paleozoic Green and greenish-gray schistose to massive irregularly-shaped bodies and lenses of mafic rocks in units Dsq and DPsc large enough to show at the scale of the map occur in the Survey Pass and Chandalar quadrangles. This unit is part of the Schist belt. SP0042006Survey Pass Metamorphic7000 Dhf_101 Hunt Fork Shale - foliated exposures Late Devonian Dark gray to black phyllite and lesser gray-green phyllite with thin layers of siliceous or calcareous metasiltstone, lithic wacke, metasandstone, and minor layers of fossiliferous metalimestone exposed along the length of the northern boundary of the maBrachiopods (late Frasnian to early Fammenian), mollusks, echinoderms; Middle to Late Devonian conodonts; SP0042044Survey Pass Metamorphic7225 Dg Granitic orthogneiss Devonian Tan to gray weathering, equigranular to porphyroblastic, fine to coarse grained metagranitic bodies ranging in size from less than a kilometer to over 20 kms across, found in both the Schist and Central belts. Generally granitic in composition and made U-Pb zircon dates for orthogneiss 390-396 Ma; 375-395 Ma for orthogneiss at Mt. Igikpak SP0042003Survey Pass Metamorphic7250 Da Amber sequence Devonian Interlayered white to medium gray weathering metarhyolite, dark green weathering metabasite, pale gray weathering marble, and brown to dark gray weathering calcareous, pelitic and carbonaceous schist exposed in two areas in the Schist belt. "MetarhyoliteOne conodont of Devonian age U-Pb zircon ages from metarhyolite layers 378-386 Ma, bimodal igneous zircon population about 378 and 405 Ma from Arctic deposit. SP0042004Survey Pass Metamorphic7260 DpCsm Schist and marble, undivided, Arrigetch-Igikpak thermal high Devonian to Proterozoic? Gray marble, orange dolomitic marble, magnetite-bearing chlorite schist, and pelitic schist exposed in the central Survey Pass quadrangle. Adjacent to the Arrigetch pluton, the unit contains calc-silicate skarn. Mineral assemblages from most of the uni SP0042048Survey Pass Metamorphic7360 DpCgn Schist and paragneiss Devonian to Proterozoic? Pelitic schist, metaquartzite, mafic schist and other lithologies; gneissic textures are more common where the unit is adjacent to metaplutonic rocks. Mafic rocks within the unit contain assemblages stable in the albite-epidote-amphibolite facies; expo SP0042045Survey Pass Metamorphic7361 OpCc_541 Older carbonate rocks of the Central belt, restricted Middle Ordovician to Proterozoic? Dolostone, metalimestone, marble and subordinate quartzose metasedimentary rocks, carbonate conglomerate, and metabasite. Only exposures that contain the Ordovician part of unit OPc are included in this unit. Conodonts, stromatolites, protoconodonts, chancellorid sclerites, hyolithids, and steinkerns of monoplacophoran mollusks, acrotretid brachiopods,agnostid arthropods, graptolites SP0042042Survey Pass Metamorphic7741 Dsq Quartz-mica schist Devonian Gray, dark gray, or brownish-gray weathering, dominantly pelitic or semipelitic schist that constitutes a major unit along the length of the Schist belt. Outcrops vary from blocky and resistant (quartz-rich varieties) to platy and less resistant (mica-r Youngest detrital zircon population at one locality 370-360 Ma SP0042000Survey Pass Metamorphic8602 PzZqs Quartz-rich metasedimentary rocks Paleozoic to Proterozoic? Relatively homogeneous assemblage dominated by light greenish-gray fine-grained quartz-rich schist, typically accompanied by minor layers of metaconglomerate, marble, and calcareous schist. Exposed in the southern Central belt in the western Survey PassConodont SP0042021Survey Pass Metamorphic8603 PzZb Metasedimentary rocks of Bluecloud Mountain Paleozoic to Proterozoic? Light, medium, and dark gray phyllite, dark gray to black metaquartzite, dark gray and grayish-brown calcareous phyllite, and reddish-brown weathering impure marble exposed in fault-bounded lenses along the Schist belt-Central belt contact in the Wiseman SP0042002Survey Pass Metamorphic8604 DpCsc Calcareous schist, Schist belt Devonian to Proterozoic Light gray, brown and locally orange-weathering, lithologically heterogeneous mix of marble and carbonate-rich, quartz-rich, and mafic schist derived from metasedimentary and metaigneous protoliths, one of two major units that extends along the length ofGhosts of radiolarians, sponge spicules, bivalves, fine graphite laminae, stromatolites, conodonts SP0042001Survey Pass Metamorphic8605 DpCsc_101Calcareous schist - metachert and conglomerate subunit, Schist belt Devonian to Proterozoic Light gray, brown and locally orange-weathering, lithologically heterogeneous mix of marble and carbonate-rich, quartz-rich, and mafic schist derived from metasedimentary and metaigneous protoliths, one of two major units that extends along the length ofGhosts of radiolarians, sponge spicules, bivalves, fine graphite laminae, stromatolites, conodonts SP0042041Survey Pass Metamorphic8608 PzZem Metamorphic rocks of the Ernie Lake area Paleozoic to Proterozoic Coarse crystalline marble, orange dolomitic marble, quartz-mica schist, metaquartzite, calcareous schist, graphitic metaquartzite, and metabasite exposed in eastern Survey Pass and western Wiseman quadrangles. Locally gneissic. This unit is part of the C Protolith intruded by 971 Ma granitic rock SP0042012Survey Pass Metamorphic8611 PzZcm Metasedimentary and metavolcanic rocks, undivided Paleozoic and Proterozoic? Heterogeneous assemblage of interlayered calcareous, mafic, and siliceous rocks exposed in the central Baird Mountains, Ambler River, and Wiseman quadrangles. This unit is part of the Central belt. Conodonts SP0042046Survey Pass Metamorphic8655 PzZm Mafic schist Proterozoic? to Paleozoic? Dark green weathering foliated mafic schist exposed in one area on the boundary between the Ambler River and Survey Pass quadrangles. This unit is part of the Central belt. SP0042047Survey Pass Metamorphic8661 pCg Granitic orthogneiss Paleozoic Metagranitic rocks of several Proterozoic ages exposed in southern Baird Mountains and western Wiseman quadrangles. U-Pb zircon ages: southern Baird Mtns quad - 705+/-35 Ma; Ernie Lake pluton - 971+/-5 Ma; Mt. Angayukaqsraq - 750 +/- 6 Ma SP0042011Survey Pass Metamorphic9060 Qs Surficial sedimentary deposits, undivided Quaternary Frost-rived rubble on slopes and broad low ridges; glacially deposted sand, gravel, and boulders; fluvial gravel and sand; terrace deposits. WI0072040Wiseman Sedimentary100 1000 Ks Conglomerate, sandstone, and shale Cretaceous Conglomerate and finer grained sedimentary rocks that grade from massive, poorly stratified rocks rich in mafic intrusive and extrusive clasts at the base of the unit to a well-sorted sedimentary rock rich in quartz and metagraywacke clasts at the top ofSparse plant fossils of Early to Late Cretaceous age; Early Cretaceous? marine mollusks WI0072038Wiseman Sedimentary1990 Kvg Volcanic-clast graywacke and mudstone Cretaceous Fine grained to conglomeratic greywacke and fine-grained laminated mudstone exposed along the south-central boundary of the map. Mudstone is locally tuffaceous. Clasts are predominantly intermediate and mafic volcanic and intrusive rocks and chert with Marine mollusks of Late Early Cretaceous (Albian) age WI0072091Wiseman Sedimentary2180 Kg Granitic rocks Cretaceous Granite, quartz monzonite, and granodiorite of the northern Ruby terrane, exposed along the southern boundary of the Chandalar quadrangle. Includes one large polygon south-southwest of Caro mapped by Brosge and Reiser as part of their unit MzPzg; remain K-Ar dates from south of map area are 96-112 Ma WI0072037Wiseman Igneous 2492 Khs Rocks of the Hammond River shear zone Cretaceous? Heterogeneous mix of finely laminated, mostly mylonitic lithologies derived in part from adjacent units exposed in the eastern Wiseman and western Chandalar quadrangles. Unit is recessive, poorly exposed, and includes large (up to 0.5 km across) bodies WI0072022Wiseman Metamorphic2650 JCs Sedimentary rocks Jurassic to Carboniferous Sandstone, shale, argillaceous limestone, limestone, dolostone, mudstone, chert and siltstone in north-central Wiseman quadrangle. The unit conformably overlies the Kanayut Conglomerate of the Endicott Group. Consists of Kayak Shale of the Endicott GrouForaminifers; cephalopods, sponge spicules, and radiolarians; burrows and grazing traces WI0072090Wiseman Sedimentary5003 TrCs Sedimentary rocks Triassic to Carboniferous Quartzite, phyllite, siltstone, conglomerate, shale, sandstone, limestone, argillaceous limestone, dolomitic limestone, and cherty dolostone. Occurs in the Mount Doonerak area in northeastern Wiseman and northwestern Chandalar quadrangles, where it is iConodonts; foraminifers; crinoidal packstone; burrows and trace fossils; brachiopods Wolfcampian age WI0072026Wiseman Sedimentary5004 JDab Mafic metavolcanic and metaintrusive rocks, metachert, metalimestone, and amphibolite of the Angayucham terrane Early Jurassic to Devonian Metamorphosed pillow basalt, hyaloclastic breccia, basaltic tuff, diabase, microgabbro, radiolarian and tuffaceous chert, minor metalimestone, and rare mafic schist in an imbricate package exposed along the southern boundary of the map area. Commonly, meRadiolarians, conodonts, megafossils, foraminifers, bryozoans, brachiopods WI0072009Wiseman Metamorphic5133 Pzpg Phyllite and graywacke Paleozoic? Dark gray to black phyllite and brown-weathering greywacke, sandstone, and mudstone exposed along the southern boundary of the schist belt. The unit varies in breadth along strike. In the Wiseman and Chandalar quadrangles, two subunits are recognized: WI0072007Wiseman Metamorphic5565 Pzbs Black metasedimentary rocks Paleozoic Dark gray to black phyllite and calcareous phyllite with dark gray to orange-weathering marble and dolostone layers up to 50 m thick, exposed in the northeastern Survey Pass and northwestern Wiseman quadrangles. This unit is part of the Central belt. Brachiopods Middle Devonian or Frasnian (early Late Devonian) WI0072085Wiseman Metamorphic6331 Mc Quartz-rich conglomerate Mississippian? Quartz- , chert-, quartzite-, and slate-clast conglomerate with minor thin layers of metasandstone and phyllite exposed in the Ambler River, Survey Pass, and Wiseman quadrangles. Quartz and chert clasts are most common; chert clasts are varicolored. Th WI0072077Wiseman Metamorphic6360 Mu Metasedimentary rocks, undivided Mississippian Quartz conglomerate, quartzite, metasandstone, phyllite, shale, and metalimestone in the Ambler River, Survey Pass, and Wiseman quadrangles. Crinoids, brachiopods, corals, foraminifers, gastropods, molluscan and echinoderm debris, possible bryozoan, pelecypod, brachiopod, ostracode fragments, foraminifers WI0072062Wiseman Metamorphic6365 SCvs Volcanic and sedimentary rocks Silurian to Cambrian Volcanic rocks, volcaniclastic rocks, and clastic sedimentary rocks exposed in the core of the Doonerak antiform, northeast Wiseman quadrangle. The unit can be divided into at least two lithologic sequences, one dominated by volcanic rocks, the other byMicrofossils, brachiopods, trilobites, graptolites, conodonts K-Ar and Ar-Ar ages of dikes 373-388 Ma and 478 Ma WI0072057Wiseman Sedimentary6720 Pzj Metasedimentary rocks of Jesse Mountain Paleozoic Generally fine grained, phyllitic to schistose, gray-weathering meta-argillite, black-weathering metaquartzite, marble, and brown weathering impure marble, exposed in a single area in the eastern Wiseman quadrangle. This unit is part of the Central belConodonts; brachiopods; coral fragments WI0072032Wiseman Metamorphic6850 MDk_101 Kanuyut Conglomerate and Noatak Sandstone Lower Mississippian? and Upper DevonianQuartzite, pebbly quartzite, conglomerate, and minor siltstone. This unit includes exposures where Kanayut has not been differentiated from Noatak Sandstone. Echinoderm debris, brachiopods, mollusks, cephalopods, and plant fragments WI0072089Wiseman Metamorphic6914 Dhf Hunt Fork Shale Late Devonian Dark gray to black phyllite and lesser gray-green phyllite with thin layers of siliceous or calcareous metasiltstone, lithic wacke, metasandstone, and minor layers of fossiliferous metalimestone exposed along the length of the northern boundary of the maBrachiopods (late Frasnian to early Fammenian), mollusks, echinoderms; Middle to Late Devonian conodonts; WI0072018Wiseman Metamorphic6925 Pzw Metasedimentary rocks Paleozoic Weakly metamorphosed metasandstone, meta-argillite, phyllite, conglomerate, and rare marble exposed in two belts on the Wiseman/Chandalar quadangle boundary. This subunit, the northern belt, is composed of metasandstone and argillite, and contains abund Detrital white mica -Ordovician 40Ar/39Ar cooling age WI0072055Wiseman Metamorphic6927 Pzw_572 Metasedimentary rocks Paleozoic Weakly metamorphosed metasandstone, meta-argillite, phyllite, conglomerate, and rare marble exposed in two belts on the Wiseman/Chandalar quadangle boundary. This subunit, the southern of the two belts, is composed of phyllite, metasandstone with volcaConodonts, bryozoans, corals WI0072055Wiseman Metamorphic6927 Dmu Metasedimentary and lesser metaigneous rocks Middle and Late Devonian Heterogeneous expanses of calcareous, siliceous, and volcaniclastic metasedimentary rocks, with lesser metaigneous rocks, exposed along the length of the Central belt. Includes significant expanses of rocks mapped as Beaucoup Formation by some workers. TMegafossils and conodonts are Middle and early Late Devonian U-Pb zircon crystallization age of 393+/-2 Ma from subunit that contains felsic to intermediate volcanic rocks WI0072017Wiseman Metamorphic6927 Dmu_542 Metasedimentary and lesser metaigneous rocks, calcareous, iron-rich components Middle and Late Devonian Part of heterogeneous expanses of calcareous, siliceous, and volcaniclastic metasedimentary rocks, with lesser metaigneous rocks, exposed along the length of the Central belt. This part of the unit contains a light brown, gray, and orange-weathering ferMegafossils and conodonts are Middle and early Late Devonian U-Pb zircon crystallization age of 393+/-2 Ma from subunit that contains felsic to intermediate volcanic rocks WI0072052Wiseman Metamorphic6972 Dmu_541 Metasedimentary and lesser metaigneous rocks, volcanic-rock bearing subunit Middle and Late Devonian Part of heterogeneous expanses of calcareous, siliceous, and volcaniclastic metasedimentary rocks, with lesser metaigneous rocks, exposed along the length of the Central belt, thought to be correlative with the Beaucoup Formation. This subunit containMegafossils and conodonts are Middle and early Late Devonian U-Pb zircon crystallization age of 393+/-2 Ma from a foliated felsic rock WI0072043Wiseman Metamorphic6973 Pzm Marble Paleozoic White to gray (less commonly black), fine to coarsely crystalline, massive to platy marble and subordinate metalimestone and dolostone occurs discontinuously in all quadrangles within the map area. This unit is part of the Central belt. Conodonts, silicified two-hole crinoid columnals of late Early-early Middle Devonian (late Emsian-Eifelian) age; brachiopods; possible stromatoporoids; pelmatozoan; trilobites WI0072023Wiseman Metamorphic6983 Dhf_101 Hunt Fork Shale - foliated exposures Late Devonian Dark gray to black phyllite and lesser gray-green phyllite with thin layers of siliceous or calcareous metasiltstone, lithic wacke, metasandstone, and minor layers of fossiliferous metalimestone exposed along the length of the northern boundary of the maBrachiopods (late Frasnian to early Fammenian), mollusks, echinoderms; Middle to Late Devonian conodonts; WI0072044Wiseman Metamorphic7225 Dg Granitic orthogneiss Devonian Tan to gray weathering, equigranular to porphyroblastic, fine to coarse grained metagranitic bodies ranging in size from less than a kilometer to over 20 kms across, found in both the Schist and Central belts. Generally granitic in composition and made U-Pb zircon dates for orthogneiss 390-396 Ma; 375-395 Ma for orthogneiss at Mt. Igikpak WI0072003Wiseman Metamorphic7250 Da Amber sequence Devonian Interlayered white to medium gray weathering metarhyolite, dark green weathering metabasite, pale gray weathering marble, and brown to dark gray weathering calcareous, pelitic and carbonaceous schist exposed in two areas in the Schist belt. "MetarhyoliteOne conodont of Devonian age U-Pb zircon ages from metarhyolite layers 378-386 Ma, bimodal igneous zircon population about 378 and 405 Ma from Arctic deposit. WI0072004Wiseman Metamorphic7260 OpCc_541 Older carbonate rocks of the Central belt, restricted Middle Ordovician to Proterozoic? Dolostone, metalimestone, marble and subordinate quartzose metasedimentary rocks, carbonate conglomerate, and metabasite. Only exposures that contain the Ordovician part of unit OPc are included in this unit. Conodonts, stromatolites, protoconodonts, chancellorid sclerites, hyolithids, and steinkerns of monoplacophoran mollusks, acrotretid brachiopods,agnostid arthropods, graptolites WI0072042Wiseman Metamorphic7741 Dsq Quartz-mica schist Devonian Gray, dark gray, or brownish-gray weathering, dominantly pelitic or semipelitic schist that constitutes a major unit along the length of the Schist belt. Outcrops vary from blocky and resistant (quartz-rich varieties) to platy and less resistant (mica-r Youngest detrital zircon population at one locality 370-360 Ma WI0072000Wiseman Metamorphic8602 PzZqs Quartz-rich metasedimentary rocks Paleozoic to Proterozoic? Relatively homogeneous assemblage dominated by light greenish-gray fine-grained quartz-rich schist, typically accompanied by minor layers of metaconglomerate, marble, and calcareous schist. Exposed in the southern Central belt in the western Survey PassConodont WI0072021Wiseman Metamorphic8603 PzZb Metasedimentary rocks of Bluecloud Mountain Paleozoic to Proterozoic? Light, medium, and dark gray phyllite, dark gray to black metaquartzite, dark gray and grayish-brown calcareous phyllite, and reddish-brown weathering impure marble exposed in fault-bounded lenses along the Schist belt-Central belt contact in the Wiseman WI0072002Wiseman Metamorphic8604 DpCsc Calcareous schist, Schist belt Devonian to Proterozoic Light gray, brown and locally orange-weathering, lithologically heterogeneous mix of marble and carbonate-rich, quartz-rich, and mafic schist derived from metasedimentary and metaigneous protoliths, one of two major units that extends along the length ofGhosts of radiolarians, sponge spicules, bivalves, fine graphite laminae, stromatolites, conodonts WI0072001Wiseman Metamorphic8605 DpCsc_101Calcareous schist - metachert and conglomerate subunit, Schist belt Devonian to Proterozoic Light gray, brown and locally orange-weathering, lithologically heterogeneous mix of marble and carbonate-rich, quartz-rich, and mafic schist derived from metasedimentary and metaigneous protoliths, one of two major units that extends along the length ofGhosts of radiolarians, sponge spicules, bivalves, fine graphite laminae, stromatolites, conodonts WI0072041Wiseman Metamorphic8608 PzZem Metamorphic rocks of the Ernie Lake area Paleozoic to Proterozoic Coarse crystalline marble, orange dolomitic marble, quartz-mica schist, metaquartzite, calcareous schist, graphitic metaquartzite, and metabasite exposed in eastern Survey Pass and western Wiseman quadrangles. Locally gneissic. This unit is part of the C Protolith intruded by 971 Ma granitic rock WI0072012Wiseman Metamorphic8611 PzZcm Metasedimentary and metavolcanic rocks, undivided Paleozoic and Proterozoic? Heterogeneous assemblage of interlayered calcareous, mafic, and siliceous rocks exposed in the central Baird Mountains, Ambler River, and Wiseman quadrangles. This unit is part of the Central belt. Conodonts WI0072046Wiseman Metamorphic8655 DpCm Metamorphic rocks, Mosquito terrane Devonian to Proterozoic? Pelitic schist, metabasite, minor felsic orthogneiss and meta-ultramafic rock exposed in two small areas along the Kobuk fault zone in the northeast Bettles and southwest Chandalar quadrangles. The rocks exhibit amphibolite-facies metamorphic assemblage 54.8 +/- 1.3 Ma white mica cooling age WI0072008Wiseman Metamorphic8852 pCg Granitic orthogneiss Paleozoic Metagranitic rocks of several Proterozoic ages exposed in southern Baird Mountains and western Wiseman quadrangles. U-Pb zircon ages: southern Baird Mtns quad - 705+/-35 Ma; Ernie Lake pluton - 971+/-5 Ma; Mt. Angayukaqsraq - 750 +/- 6 Ma WI0072011Wiseman Metamorphic9060