«áßNSACLASSNLABELCNAMEC¡AGEC7DESCRIPTIOCþSOURCESCþ 99 bu Bedrock of unknown type or age Areas that air photo interpretation suggest as being underlain by bedrock. Typically are of higher elevation than surrounding glacial deposits and show hints of structure. Also includes rubble of metasiltstone and chert in the Kantishna River quadranglWilson, F.H., Dover, J.H., Bradley, D.C., Weber, F.R., Bundtzen, T.K., and Haeussler, P.J., 1998, Geologic map of Central (Interior) Alaska: U.S. Geological Survey Open-File Report 98-133, 3 sheets, scale 1:500,000, 63 p. pamphlet, 13 p. appendix. 100 Qua Surficial deposits, undifferentiated Quaternary Chiefly silt and very fine sand including thick deposits of micaeous silt in the Koyukuk Flats and Nowitna and Innoko Lowlands. Local deposits of alluvial fan and glacial outwash gravels Patton, W.W., Jr., Wilson, F.H., Labay, K.A., and Shew, Nora, in prep., Reconnaissance geologic map and digital data for the Yukon-Koyukuk basin, Alaska - (Integrated digital geologic map databases of the United States): U.S. Geological Survey Scientifi 105 Qf Floodplain and tidal flats deposits Holocene Gravel, sand, silt, and peat. Floodplain deposits in Koyukuk Flats and along Yukon River composed mainly of light gray micaceous silt Wilson, F.H., Dover, J.H., Bradley, D.C., Weber, F.R., Bundtzen, T.K., and Haeussler, P.J., 1998, Geologic map of Central (Interior) Alaska: U.S. Geological Survey Open-File Report 98-133, 3 sheets, scale 1:500,000, 63 p. pamphlet, 13 p. appendix. 107 Qua Surficial deposits, undifferentiated Quaternary Chiefly silt and very fine sand including thick deposits of micaeous silt in the Koyukuk Flats and Nowitna and Innoko Lowlands. Local deposits of alluvial fan and glacial outwash gravels Patton, W.W., Jr., Wilson, F.H., Labay, K.A., and Shew, Nora, in prep., Reconnaissance geologic map and digital data for the Yukon-Koyukuk basin, Alaska - (Integrated digital geologic map databases of the United States): U.S. Geological Survey Scientifi 108 Qua Surficial deposits, undifferentiated Quaternary Chiefly silt and very fine sand including thick deposits of micaeous silt in the Koyukuk Flats and Nowitna and Innoko Lowlands. Local deposits of alluvial fan and glacial outwash gravels Patton, W.W., Jr., Wilson, F.H., Labay, K.A., and Shew, Nora, in prep., Reconnaissance geologic map and digital data for the Yukon-Koyukuk basin, Alaska - (Integrated digital geologic map databases of the United States): U.S. Geological Survey Scientifi 110 Qua Surficial deposits, undifferentiated Quaternary Chiefly silt and very fine sand including thick deposits of micaeous silt in the Koyukuk Flats and Nowitna and Innoko Lowlands. Local deposits of alluvial fan and glacial outwash gravels Patton, W.W., Jr., Wilson, F.H., Labay, K.A., and Shew, Nora, in prep., Reconnaissance geologic map and digital data for the Yukon-Koyukuk basin, Alaska - (Integrated digital geologic map databases of the United States): U.S. Geological Survey Scientifi 111 Qf Floodplain and tidal flats deposits Holocene Gravel, sand, silt, and peat. Floodplain deposits in Koyukuk Flats and along Yukon River composed mainly of light gray micaceous silt Wilson, F.H., Dover, J.H., Bradley, D.C., Weber, F.R., Bundtzen, T.K., and Haeussler, P.J., 1998, Geologic map of Central (Interior) Alaska: U.S. Geological Survey Open-File Report 98-133, 3 sheets, scale 1:500,000, 63 p. pamphlet, 13 p. appendix. 116 Qf Floodplain and tidal flats deposits Holocene Gravel, sand, silt, and peat. Floodplain deposits in Koyukuk Flats and along Yukon River composed mainly of light gray micaceous silt Wilson, F.H., Dover, J.H., Bradley, D.C., Weber, F.R., Bundtzen, T.K., and Haeussler, P.J., 1998, Geologic map of Central (Interior) Alaska: U.S. Geological Survey Open-File Report 98-133, 3 sheets, scale 1:500,000, 63 p. pamphlet, 13 p. appendix. 119 Qsa Actively drifting and recently stabilized dune fields Holocene Fine- to coarse-grained sand. Great Kobuk and Little Kobuk Sand Dunes in the southwestern Ambler River and southeastern Baird Mountains quadrangles, and Nogahabara Sand Dunes in the Kateel River quadrangle. The Great Kobuk and Little Kobuk dune fieldsPatton, W.W., Jr., Wilson, F.H., Labay, K.A., and Shew, Nora, in prep., Reconnaissance geologic map and digital data for the Yukon-Koyukuk basin, Alaska - (Integrated digital geologic map databases of the United States): U.S. Geological Survey Scientifi 120 Qs Eolian and water-laid sand and silt sheets and stabilized dune fields Holocene and Pleistocene Sand and coarse silt. 1) Baird Mountains, Ambler River, Selawik, and Shungnak quadrangles: Modified and partly dissected sheets of mixed wind-blown and water-laid deposits bordering the south edge of the Brooks Range; 2) Kateel River and Melozitna Patton, W.W., Jr., Wilson, F.H., Labay, K.A., and Shew, Nora, in prep., Reconnaissance geologic map and digital data for the Yukon-Koyukuk basin, Alaska - (Integrated digital geologic map databases of the United States): U.S. Geological Survey Scientifi 125 QTgl Glacial and glaciolacustrine deposits Pleistocene and Pliocene? Includes unsorted to poorly sorted till, outwash sand and gravel, alluvium, and eolian deposits. Along the southern edge of the Brooks Range, unit is characterized by little-modified middle and late Pleistocene drift including prominent morainal ridges Patton, W.W., Jr., Wilson, F.H., Labay, K.A., and Shew, Nora, in prep., Reconnaissance geologic map and digital data for the Yukon-Koyukuk basin, Alaska - (Integrated digital geologic map databases of the United States): U.S. Geological Survey Scientifi 135 QTgl Glacial and glaciolacustrine deposits Pleistocene and Pliocene? Includes unsorted to poorly sorted till, outwash sand and gravel, alluvium, and eolian deposits. Along the southern edge of the Brooks Range, unit is characterized by little-modified middle and late Pleistocene drift including prominent morainal ridges Patton, W.W., Jr., Wilson, F.H., Labay, K.A., and Shew, Nora, in prep., Reconnaissance geologic map and digital data for the Yukon-Koyukuk basin, Alaska - (Integrated digital geologic map databases of the United States): U.S. Geological Survey Scientifi 190 QTgl Glacial and glaciolacustrine deposits Pleistocene and Pliocene? Includes unsorted to poorly sorted till, outwash sand and gravel, alluvium, and eolian deposits. Along the southern edge of the Brooks Range, unit is characterized by little-modified middle and late Pleistocene drift including prominent morainal ridges Patton, W.W., Jr., Wilson, F.H., Labay, K.A., and Shew, Nora, in prep., Reconnaissance geologic map and digital data for the Yukon-Koyukuk basin, Alaska - (Integrated digital geologic map databases of the United States): U.S. Geological Survey Scientifi 285 QTgr Quartz gravel deposits Quaternary or Tertiary High-level deposits of quartz pebble gravel; overlies basalt flows of unit Tb Patton, W.W., Jr., Wilson, F.H., Labay, K.A., and Shew, Nora, in prep., Reconnaissance geologic map and digital data for the Yukon-Koyukuk basin, Alaska - (Integrated digital geologic map databases of the United States): U.S. Geological Survey Scientifi 300 Qab Alkalic basalt cones and flows Pleistocene Unit comprises numerous alkali basalt, basanite, and hawaiite cones, short flows, and maar craters. Cones and flows have little or no vegetative cover and still preserve some primary flow structures. Locally contains peridotite and pyroxenite xenoliths.Patton, W.W., Jr., Wilson, F.H., Labay, K.A., and Shew, Nora, in prep., Reconnaissance geologic map and digital data for the Yukon-Koyukuk basin, Alaska - (Integrated digital geologic map databases of the United States): U.S. Geological Survey Scientifi 305 Qtb Tholeiitic basalt cones and flows Holocene? and Pleistocene Black glassy olivine tholeiitic basalt flows erupted from two small craters. Flows exhibit well-developed pahoehoe crusts and lack vegetative cover. One K/Ar isotopic determination from this unit gave a cooling age of 0.19 Ma Patton, W.W., Jr., Wilson, F.H., Labay, K.A., and Shew, Nora, in prep., Reconnaissance geologic map and digital data for the Yukon-Koyukuk basin, Alaska - (Integrated digital geologic map databases of the United States): U.S. Geological Survey Scientifi 350 QTb Basalt flows Pleistocene and Pliocene Includes the Wrangell Lava consisting chiefly of basalt and andesite in the southeastern part of the map area and olivine basalt and vesicular andesite in the northern part of the map area Patton, W.W., Jr., Wilson, F.H., Labay, K.A., and Shew, Nora, in prep., Reconnaissance geologic map and digital data for the Yukon-Koyukuk basin, Alaska - (Integrated digital geologic map databases of the United States): U.S. Geological Survey Scientifi 640 Ts Small deposits of nonmarine conglomerate, sandstone, shale, and coal Tertiary Poorly consolidated nonmarine deposits occur in five areas listed below; the first three are located close to the Kaltag Fault. Pollen samples from these five areas range in age from Oligocene to Pliocene.: 1) Unalakleet quadrangle. Clay shale, lignPatton, W.W., Jr., Wilson, F.H., Labay, K.A., and Shew, Nora, in prep., Reconnaissance geologic map and digital data for the Yukon-Koyukuk basin, Alaska - (Integrated digital geologic map databases of the United States): U.S. Geological Survey Scientifi 1001Trs Rhyolitic volcanic and sedimentary rocks Tertiary? Rhyolitic volcanic and minor(?) associated sedimentary rocks are mapped in a small area in the Tanana quadrangle (Chapman and others, 1982; Dover, unpublished data, 1997). Rhyolitic rocks consist of light- to very light-yellow and yellowish-gray to creaPatton, W.W., Jr., Wilson, F.H., Labay, K.A., and Shew, Nora, in prep., Reconnaissance geologic map and digital data for the Yukon-Koyukuk basin, Alaska - (Integrated digital geologic map databases of the United States): U.S. Geological Survey Scientifi 1002Td Dacite and rhyolite lava flows, domes, and volcaniclastic rocks Eocene and Paleocene Finely banded dacitic and rhyolitic lava flows, basal breccia, tuffs, obsidian, and hypabyssal domal intrusive bodies. Spatially associated with andesite and basalt unit (Ta) and forms a compositionally continuous suite with unit Ta. K/Ar isotopic cooPatton, W.W., Jr., Wilson, F.H., Labay, K.A., and Shew, Nora, in prep., Reconnaissance geologic map and digital data for the Yukon-Koyukuk basin, Alaska - (Integrated digital geologic map databases of the United States): U.S. Geological Survey Scientifi 1004Tb Basalt flows Oligocene Vesicular and columnar-jointed basalt flows and lahar deposits. Unit yielded a K/Ar cooling age of 32 Ma Patton, W.W., Jr., Wilson, F.H., Labay, K.A., and Shew, Nora, in prep., Reconnaissance geologic map and digital data for the Yukon-Koyukuk basin, Alaska - (Integrated digital geologic map databases of the United States): U.S. Geological Survey Scientifi 1011Thr Rhyolite hypabyssal bodies Miocene to Paleocene, mostly Early Tertiary or Eocene?)Fine-grained porphyritic rhyolite composed of phenocrysts of plagioclase rimmed by orthoclase in a groundmass of plagioclase, orthoclase, quartz, and altered mafic minerals. Unit probably correlates and forms a compositional continuum with a nearby granPatton, W.W., Jr., Wilson, F.H., Labay, K.A., and Shew, Nora, in prep., Reconnaissance geologic map and digital data for the Yukon-Koyukuk basin, Alaska - (Integrated digital geologic map databases of the United States): U.S. Geological Survey Scientifi 1081Tad Andesite and basalt lava flows and volcaniclastic rocks (Ta) and dacite and rhyolite lava flows, domes, and volcaniclastic rocks (Td), undivided Eocene and Paleocene Confined to west-central part of Melozitna quadrangle where field data are insufficient to map units Ta and Td separately Patton, W.W., Jr., Wilson, F.H., Labay, K.A., and Shew, Nora, in prep., Reconnaissance geologic map and digital data for the Yukon-Koyukuk basin, Alaska - (Integrated digital geologic map databases of the United States): U.S. Geological Survey Scientifi 1103Ta Andesite and basalt lava flows and volcaniclastic rocks Eocene and Paleocene Subaerial, columnar-jointed, andesite and basalt lava flows that locally contain interbedded tuffs, breccias, and agglomerates. Lava flows composed chiefly of pyroxene andesite and less commonly of hornblende-bearing high-silica andesite, olivine-bearinPatton, W.W., Jr., Wilson, F.H., Labay, K.A., and Shew, Nora, in prep., Reconnaissance geologic map and digital data for the Yukon-Koyukuk basin, Alaska - (Integrated digital geologic map databases of the United States): U.S. Geological Survey Scientifi 1120Tt Tuff and tuff breccia Eocene or Paleocene Tuff and breccia are composed of abundant lithic fragments of flow-banded rhyolite and partially welded pumice in a matrix of devitrified glass shards, altered plagioclase, quartz, and mafic minerals. Unit contains subordinate altered andesite and daciPatton, W.W., Jr., Wilson, F.H., Labay, K.A., and Shew, Nora, in prep., Reconnaissance geologic map and digital data for the Yukon-Koyukuk basin, Alaska - (Integrated digital geologic map databases of the United States): U.S. Geological Survey Scientifi 1320Tg Granite Eocene or Paleocene Fine-grained equigranular to sparsely porphyritic granite characterized by plagioclase laths mantled by orthoclase. One K/Ar isotopic determination from this unit yielded a cooling age of 56 Ma Patton, W.W., Jr., Wilson, F.H., Labay, K.A., and Shew, Nora, in prep., Reconnaissance geologic map and digital data for the Yukon-Koyukuk basin, Alaska - (Integrated digital geologic map databases of the United States): U.S. Geological Survey Scientifi 1510TKd Dacite and rhyolite lava flows, domes, and volcaniclastic and hypabyssal rocks early Tertiary and Late Cretaceous Dacite, rhyolite, and trachyandesite lava flows, domes, sills, dikes, and interlayered breccias and tuffs. Composed of phenocrysts of plagioclase, quartz, sanidine, and biotite in a groundmass of quartz and feldspar. Locally in Unalakleet and Medfra qPatton, W.W., Jr., Wilson, F.H., Labay, K.A., and Shew, Nora, in prep., Reconnaissance geologic map and digital data for the Yukon-Koyukuk basin, Alaska - (Integrated digital geologic map databases of the United States): U.S. Geological Survey Scientifi 1600TKad Andesite and basalt lava flows and volcaniclastic rocks (TKa) and dacite and rhyolite lava flows, domes, and volcaniclastic and hypabyssal rocks (TKd), undividedearly Tertiary and Late Cretaceous Andesite and basalt lava flows and volcaniclastic rocks (TKa) and dacite and rhyolite lava flows, domes, and volcaniclastic and hypabyssal rocks (TKd), undivided Patton, W.W., Jr., Wilson, F.H., Labay, K.A., and Shew, Nora, in prep., Reconnaissance geologic map and digital data for the Yukon-Koyukuk basin, Alaska - (Integrated digital geologic map databases of the United States): U.S. Geological Survey Scientifi 1601TKi Shallow intrusive rocks of silicic and intermediate composition Tertiary and Late Cretaceous Includes a wide variety of shallow intrusive rocks including rhyolite, dacite, trachyite, and andesite plugs, domes, sills, and dikes and larger more coarsely crystalline bodies of granite, granodiorite, tonalite, and monzonite porphyry Patton, W.W., Jr., Wilson, F.H., Labay, K.A., and Shew, Nora, in prep., Reconnaissance geologic map and digital data for the Yukon-Koyukuk basin, Alaska - (Integrated digital geologic map databases of the United States): U.S. Geological Survey Scientifi 1602TKi Shallow intrusive rocks of silicic and intermediate composition Tertiary and Late Cretaceous Includes a wide variety of shallow intrusive rocks including rhyolite, dacite, trachyite, and andesite plugs, domes, sills, and dikes and larger more coarsely crystalline bodies of granite, granodiorite, tonalite, and monzonite porphyry Patton, W.W., Jr., Wilson, F.H., Labay, K.A., and Shew, Nora, in prep., Reconnaissance geologic map and digital data for the Yukon-Koyukuk basin, Alaska - (Integrated digital geologic map databases of the United States): U.S. Geological Survey Scientifi 1603TKd Dacite and rhyolite lava flows, domes, and volcaniclastic and hypabyssal rocks early Tertiary and Late Cretaceous Dacite, rhyolite, and trachyandesite lava flows, domes, sills, dikes, and interlayered breccias and tuffs. Composed of phenocrysts of plagioclase, quartz, sanidine, and biotite in a groundmass of quartz and feldspar. Locally in Unalakleet and Medfra qPatton, W.W., Jr., Wilson, F.H., Labay, K.A., and Shew, Nora, in prep., Reconnaissance geologic map and digital data for the Yukon-Koyukuk basin, Alaska - (Integrated digital geologic map databases of the United States): U.S. Geological Survey Scientifi 1604TKvr Rhyolite and related rocks Tertiary and/or Cretaceous Consists of light gray to pink rhyolitic volcanic rocks and minor dacite, including flows, tuff, welded(?) tuff and breccia. Exposures of this unit include the volcanic rocks of the Big Creek -- Tokatjikh Creek area of the Melozitna quadrangle (mapped aWilson, F.H., Dover, J.H., Bradley, D.C., Weber, F.R., Bundtzen, T.K., and Haeussler, P.J., 1998, Geologic map of Central (Interior) Alaska: U.S. Geological Survey Open-File Report 98-133, 3 sheets, scale 1:500,000, 63 p. pamphlet, 13 p. appendix. 1605TKa Andesite and basalt lava flows and volcaniclastic rocks early Tertiary and Late Cretaceous Columnar-jointed andesite, basaltic andesite, and basalt lava flows. Composed of phenocrysts of plagioclase and pyroxene in a fine-grained groundmass of plagioclase microlites, granular pyroxene, and dark glass. K/Ar isotopic cooling ages range from 6Patton, W.W., Jr., Wilson, F.H., Labay, K.A., and Shew, Nora, in prep., Reconnaissance geologic map and digital data for the Yukon-Koyukuk basin, Alaska - (Integrated digital geologic map databases of the United States): U.S. Geological Survey Scientifi 1620TKi Shallow intrusive rocks of silicic and intermediate composition Tertiary and Late Cretaceous Includes a wide variety of shallow intrusive rocks including rhyolite, dacite, trachyite, and andesite plugs, domes, sills, and dikes and larger more coarsely crystalline bodies of granite, granodiorite, tonalite, and monzonite porphyry Patton, W.W., Jr., Wilson, F.H., Labay, K.A., and Shew, Nora, in prep., Reconnaissance geologic map and digital data for the Yukon-Koyukuk basin, Alaska - (Integrated digital geologic map databases of the United States): U.S. Geological Survey Scientifi 1630TKvc Volcano-plutonic complexes early Tertiary and Cretaceous Complexes are composed of small, closely-spaced rhyolite, dacite, andesite, granite, granodiorite, tonalite, and monzonite porphyry bodies, which intrude Cretaceous sedimentary deposits of the Yukon-Koyukuk basin. Intrusive bodies are too small and too Patton, W.W., Jr., Wilson, F.H., Labay, K.A., and Shew, Nora, in prep., Reconnaissance geologic map and digital data for the Yukon-Koyukuk basin, Alaska - (Integrated digital geologic map databases of the United States): U.S. Geological Survey Scientifi 1641TKi Shallow intrusive rocks of silicic and intermediate composition Tertiary and Late Cretaceous Includes a wide variety of shallow intrusive rocks including rhyolite, dacite, trachyite, and andesite plugs, domes, sills, and dikes and larger more coarsely crystalline bodies of granite, granodiorite, tonalite, and monzonite porphyry Patton, W.W., Jr., Wilson, F.H., Labay, K.A., and Shew, Nora, in prep., Reconnaissance geologic map and digital data for the Yukon-Koyukuk basin, Alaska - (Integrated digital geologic map databases of the United States): U.S. Geological Survey Scientifi 1650TKi Shallow intrusive rocks of silicic and intermediate composition Tertiary and Late Cretaceous Includes a wide variety of shallow intrusive rocks including rhyolite, dacite, trachyite, and andesite plugs, domes, sills, and dikes and larger more coarsely crystalline bodies of granite, granodiorite, tonalite, and monzonite porphyry Patton, W.W., Jr., Wilson, F.H., Labay, K.A., and Shew, Nora, in prep., Reconnaissance geologic map and digital data for the Yukon-Koyukuk basin, Alaska - (Integrated digital geologic map databases of the United States): U.S. Geological Survey Scientifi 1655TKg Granite and granodiorite early Tertiary and Late Cretaceous Fine to coarse-grained, equigranular to porphyritic, biotite granite and rarely muscovite-biotite granite. K/Ar isotopic cooling ages for this unit range from 71 to 63 Ma Patton, W.W., Jr., Wilson, F.H., Labay, K.A., and Shew, Nora, in prep., Reconnaissance geologic map and digital data for the Yukon-Koyukuk basin, Alaska - (Integrated digital geologic map databases of the United States): U.S. Geological Survey Scientifi 1660TKm Monzonite early Tertiary and Late Cretaceous Medium- to coarse-grained, equigranular, biotite and hornblende monzonite, quartz monzonite, monzodiorite, and quartz diorite. Subordinate monzogabbro and gabbro. K/Ar isotopic cooling ages from this unit range from 70 to 66 Ma Patton, W.W., Jr., Wilson, F.H., Labay, K.A., and Shew, Nora, in prep., Reconnaissance geologic map and digital data for the Yukon-Koyukuk basin, Alaska - (Integrated digital geologic map databases of the United States): U.S. Geological Survey Scientifi 1680TDg Gabbro and diabase Tertiary? to Devonian? Fresh to altered gabbroic and diabasic intrusive bodies. Unit intrudes rocks as old as middle Paleozoic and as young as Cretaceous. May represent a wide range of ages Patton, W.W., Jr., Wilson, F.H., Labay, K.A., and Shew, Nora, in prep., Reconnaissance geologic map and digital data for the Yukon-Koyukuk basin, Alaska - (Integrated digital geologic map databases of the United States): U.S. Geological Survey Scientifi 1815Kcc Carbonate-clast conglomerate, sandstone, and shale Cretaceous Poorly sorted nonmarine and shallow-water shelf deposits consisting of carbonate-rich conglomerate (calcirudite), sandstone (calcarenite), and shale (calcilutite). Unit contains abundant plant debris and thin seams of bituminous coal. Clast-supported Patton, W.W., Jr., Wilson, F.H., Labay, K.A., and Shew, Nora, in prep., Reconnaissance geologic map and digital data for the Yukon-Koyukuk basin, Alaska - (Integrated digital geologic map databases of the United States): U.S. Geological Survey Scientifi 1820Kcvg Carbonate- and volcanic-clast graywacke and mudstone Cretaceous Cyclically interbedded fine- to coarse-grained highly calcareous graywacke; hard, fine- to medium-grained, carbonaceous, volcanic graywacke; and dark carbonaceous mudstone. Graywacke is typically graded and sole-marked. Carbonized plant debris is abundaPatton, W.W., Jr., Wilson, F.H., Labay, K.A., and Shew, Nora, in prep., Reconnaissance geologic map and digital data for the Yukon-Koyukuk basin, Alaska - (Integrated digital geologic map databases of the United States): U.S. Geological Survey Scientifi 1821Kcg Carbonate-clast graywacke and mudstone Cretaceous Fine-grained to gritty graywacke and laminated micaceous mudstone turbidite deposits composed largely of carbonate detritus and lesser amounts of quartz, chert, volcanic rock, and mica clasts. Contains abundant carbonized plant debris. The mudstone intePatton, W.W., Jr., Wilson, F.H., Labay, K.A., and Shew, Nora, in prep., Reconnaissance geologic map and digital data for the Yukon-Koyukuk basin, Alaska - (Integrated digital geologic map databases of the United States): U.S. Geological Survey Scientifi 1822Kcc Carbonate-clast conglomerate, sandstone, and shale Cretaceous Poorly sorted nonmarine and shallow-water shelf deposits consisting of carbonate-rich conglomerate (calcirudite), sandstone (calcarenite), and shale (calcilutite). Unit contains abundant plant debris and thin seams of bituminous coal. Clast-supported Patton, W.W., Jr., Wilson, F.H., Labay, K.A., and Shew, Nora, in prep., Reconnaissance geologic map and digital data for the Yukon-Koyukuk basin, Alaska - (Integrated digital geologic map databases of the United States): U.S. Geological Survey Scientifi 1823Kcvg Carbonate- and volcanic-clast graywacke and mudstone Cretaceous Cyclically interbedded fine- to coarse-grained highly calcareous graywacke; hard, fine- to medium-grained, carbonaceous, volcanic graywacke; and dark carbonaceous mudstone. Graywacke is typically graded and sole-marked. Carbonized plant debris is abundaPatton, W.W., Jr., Wilson, F.H., Labay, K.A., and Shew, Nora, in prep., Reconnaissance geologic map and digital data for the Yukon-Koyukuk basin, Alaska - (Integrated digital geologic map databases of the United States): U.S. Geological Survey Scientifi 1905Ksu Shale, siltstone, and sandstone, undivided Cretaceous Chiefly dark carbonaceous, generally nonfossilferous shale, siltstone and fine-grained sandstone. Poorly exposed except where altered to a dark slaty hornfels in the vicinity of plutonic and hypabyssal intrusive rocks. Locally includes a limestone-clastPatton, W.W., Jr., Wilson, F.H., Labay, K.A., and Shew, Nora, in prep., Reconnaissance geologic map and digital data for the Yukon-Koyukuk basin, Alaska - (Integrated digital geologic map databases of the United States): U.S. Geological Survey Scientifi 1906Ksu Shale, siltstone, and sandstone, undivided Cretaceous Chiefly dark carbonaceous, generally nonfossilferous shale, siltstone and fine-grained sandstone. Poorly exposed except where altered to a dark slaty hornfels in the vicinity of plutonic and hypabyssal intrusive rocks. Locally includes a limestone-clastPatton, W.W., Jr., Wilson, F.H., Labay, K.A., and Shew, Nora, in prep., Reconnaissance geologic map and digital data for the Yukon-Koyukuk basin, Alaska - (Integrated digital geologic map databases of the United States): U.S. Geological Survey Scientifi 1907Ksu Shale, siltstone, and sandstone, undivided Cretaceous Chiefly dark carbonaceous, generally nonfossilferous shale, siltstone and fine-grained sandstone. Poorly exposed except where altered to a dark slaty hornfels in the vicinity of plutonic and hypabyssal intrusive rocks. Locally includes a limestone-clastPatton, W.W., Jr., Wilson, F.H., Labay, K.A., and Shew, Nora, in prep., Reconnaissance geologic map and digital data for the Yukon-Koyukuk basin, Alaska - (Integrated digital geologic map databases of the United States): U.S. Geological Survey Scientifi 1940Kss Shallow marine sandstone, siltstone, and shale Late Cretaceous Fine-to medium-grained, thinly cross-bedded, fossiliferous sandstone and poorly exposed dark siltstone and shale. Clasts composed of 40 to 45 percent quartz, 45 to 50 percent volcanic and sedimentary lithic fragments, and 5 to 15 percent feldspar, chiPatton, W.W., Jr., Wilson, F.H., Labay, K.A., and Shew, Nora, in prep., Reconnaissance geologic map and digital data for the Yukon-Koyukuk basin, Alaska - (Integrated digital geologic map databases of the United States): U.S. Geological Survey Scientifi 1941Ks Fluvial and shallow marine sandstone and shale, undivided Cretaceous Nonmarine, fluvial, delta-plain deposits that grade downward into marine delta-front deposits. Fluvial deposits are characterized by fine-grained, locally cross-bedded quartzose sandstone interbedded with micaeous shale and siltstone. Near the base, the Patton, W.W., Jr., Wilson, F.H., Labay, K.A., and Shew, Nora, in prep., Reconnaissance geologic map and digital data for the Yukon-Koyukuk basin, Alaska - (Integrated digital geologic map databases of the United States): U.S. Geological Survey Scientifi 1942Ksu Shale, siltstone, and sandstone, undivided Cretaceous Chiefly dark carbonaceous, generally nonfossilferous shale, siltstone and fine-grained sandstone. Poorly exposed except where altered to a dark slaty hornfels in the vicinity of plutonic and hypabyssal intrusive rocks. Locally includes a limestone-clastPatton, W.W., Jr., Wilson, F.H., Labay, K.A., and Shew, Nora, in prep., Reconnaissance geologic map and digital data for the Yukon-Koyukuk basin, Alaska - (Integrated digital geologic map databases of the United States): U.S. Geological Survey Scientifi 1970Ksu Shale, siltstone, and sandstone, undivided Cretaceous Chiefly dark carbonaceous, generally nonfossilferous shale, siltstone and fine-grained sandstone. Poorly exposed except where altered to a dark slaty hornfels in the vicinity of plutonic and hypabyssal intrusive rocks. Locally includes a limestone-clastPatton, W.W., Jr., Wilson, F.H., Labay, K.A., and Shew, Nora, in prep., Reconnaissance geologic map and digital data for the Yukon-Koyukuk basin, Alaska - (Integrated digital geologic map databases of the United States): U.S. Geological Survey Scientifi 1971Kss Shallow marine sandstone, siltstone, and shale Late Cretaceous Fine-to medium-grained, thinly cross-bedded, fossiliferous sandstone and poorly exposed dark siltstone and shale. Clasts composed of 40 to 45 percent quartz, 45 to 50 percent volcanic and sedimentary lithic fragments, and 5 to 15 percent feldspar, chiPatton, W.W., Jr., Wilson, F.H., Labay, K.A., and Shew, Nora, in prep., Reconnaissance geologic map and digital data for the Yukon-Koyukuk basin, Alaska - (Integrated digital geologic map databases of the United States): U.S. Geological Survey Scientifi 1985Ksc Fluvial and shallow marine sandstone and conglomerate Late Cretaceous Fine- to coarse-grained, thinly cross-bedded sandstone and quartz-chert pebble conglomerate interbedded with dark shale and siltstone. Sandstone clasts composed of as much as 45 percent quartz and chert, 25 to 45 percent metamorphic rock, as much as 1Patton, W.W., Jr., Wilson, F.H., Labay, K.A., and Shew, Nora, in prep., Reconnaissance geologic map and digital data for the Yukon-Koyukuk basin, Alaska - (Integrated digital geologic map databases of the United States): U.S. Geological Survey Scientifi 1990Kqc Quartz- and metagraywacke-clast conglomerate, sandstone, and shale Cretaceous Composed chiefly of well-sorted and well-rounded clasts of white quartz and/or metagraywacke in a quartzose and micaceous matrix; schist, chert, greenstone, and limestone clasts occur in subordinate amounts. Conglomerate is interbedded with quartzose, cPatton, W.W., Jr., Wilson, F.H., Labay, K.A., and Shew, Nora, in prep., Reconnaissance geologic map and digital data for the Yukon-Koyukuk basin, Alaska - (Integrated digital geologic map databases of the United States): U.S. Geological Survey Scientifi 2020Ks Fluvial and shallow marine sandstone and shale, undivided Cretaceous Nonmarine, fluvial, delta-plain deposits that grade downward into marine delta-front deposits. Fluvial deposits are characterized by fine-grained, locally cross-bedded quartzose sandstone interbedded with micaeous shale and siltstone. Near the base, the Patton, W.W., Jr., Wilson, F.H., Labay, K.A., and Shew, Nora, in prep., Reconnaissance geologic map and digital data for the Yukon-Koyukuk basin, Alaska - (Integrated digital geologic map databases of the United States): U.S. Geological Survey Scientifi 2021Ks Fluvial and shallow marine sandstone and shale, undivided Cretaceous Nonmarine, fluvial, delta-plain deposits that grade downward into marine delta-front deposits. Fluvial deposits are characterized by fine-grained, locally cross-bedded quartzose sandstone interbedded with micaeous shale and siltstone. Near the base, the Patton, W.W., Jr., Wilson, F.H., Labay, K.A., and Shew, Nora, in prep., Reconnaissance geologic map and digital data for the Yukon-Koyukuk basin, Alaska - (Integrated digital geologic map databases of the United States): U.S. Geological Survey Scientifi 2023TKic Complexes of shallow intrusive rocks and altered Cretaceous sedimentary rocks of the Yukon-Koyukuk basin, undivided early Tertiary and Cretaceous Complexes are composed of small, closely-spaced rhyolite, dacite, andesite, granite, granodiorite, tonalite, and monzonite porphyry bodies, which intrude Cretaceous sedimentary deposits of the Yukon-Koyukuk basin. Intrusive bodies are too small and too Patton, W.W., Jr., Wilson, F.H., Labay, K.A., and Shew, Nora, in prep., Reconnaissance geologic map and digital data for the Yukon-Koyukuk basin, Alaska - (Integrated digital geologic map databases of the United States): U.S. Geological Survey Scientifi 2030Kmc Mafic igneous-clast conglomerate, sandstone, and mudstone Cretaceous Consists of massive poorly stratified and poorly sorted conglomerate composed of pebble- to cobble-size clasts in a graywacke and mudstone matrix. Clasts predominately mafic intrusive and extrusive rocks, varied colored chert, and locally metagraywacke.Wilson, F.H., Dover, J.H., Bradley, D.C., Weber, F.R., Bundtzen, T.K., and Haeussler, P.J., 1998, Geologic map of Central (Interior) Alaska: U.S. Geological Survey Open-File Report 98-133, 3 sheets, scale 1:500,000, 63 p. pamphlet, 13 p. appendix. 2101Kms Marine sandstone and siltstone Cretaceous The shallow marine deposits in the lower part of the unit Ks are mapped separately along the Yukon River and in a belt to the west extending from the southern edge of the Norton Bay quadrangle to the western Kateel River quadrangle. These deposits compoPatton, W.W., Jr., Wilson, F.H., Labay, K.A., and Shew, Nora, in prep., Reconnaissance geologic map and digital data for the Yukon-Koyukuk basin, Alaska - (Integrated digital geologic map databases of the United States): U.S. Geological Survey Scientifi 2105Kvgm Volcanic graywacke and mudstone Cretaceous, Albian Chiefly dark-greenish-gray, fine-grained to gritty, poorly sorted turbiditic graywacke composed largely of first- and second-cycle volcanic debris, but locally containing abundant granitic and metamorphic rock debris. Dark-gray mudstone interbeds. GradWilson, F.H., Dover, J.H., Bradley, D.C., Weber, F.R., Bundtzen, T.K., and Haeussler, P.J., 1998, Geologic map of Central (Interior) Alaska: U.S. Geological Survey Open-File Report 98-133, 3 sheets, scale 1:500,000, 63 p. pamphlet, 13 p. appendix. 2106Kvc Volcanic-clast conglomerate, sandstone, and shale Cretaceous Massive, poorly stratified pebble to boulder conglomerate, interbedded with dark graywacke and dark finely laminated mudstone. Unit composed of debris flows and alluvial fan deposits. Consists chiefly of andesitic volcanic rock detritus, but locally inPatton, W.W., Jr., Wilson, F.H., Labay, K.A., and Shew, Nora, in prep., Reconnaissance geologic map and digital data for the Yukon-Koyukuk basin, Alaska - (Integrated digital geologic map databases of the United States): U.S. Geological Survey Scientifi 2115Kwcf Wilber Creek flysch Cretaceous, Albian Interlayered siltstone, shale, sandstone, and conglomerate originally subdivided into coarse- and fine-grained units (Weber and others, 1992). Siltstone and sandstone are medium- to medium-dark-gray and greenish-gray, moderately sorted and very fine- toWilson, F.H., Dover, J.H., Bradley, D.C., Weber, F.R., Bundtzen, T.K., and Haeussler, P.J., 1998, Geologic map of Central (Interior) Alaska: U.S. Geological Survey Open-File Report 98-133, 3 sheets, scale 1:500,000, 63 p. pamphlet, 13 p. appendix. 2125Kqs Quartz-carbonate sandstone Early Cretaceous Fine- to coarse-grained quartz-carbonate sandstone and conglomerate, quartzose limestone, and pebbly mudstone and siltstone. Sandstone clasts composed chiefly of quartz, carbonate rock, and quartz-mica schist debris. Unit contains abundant marine mollPatton, W.W., Jr., Wilson, F.H., Labay, K.A., and Shew, Nora, in prep., Reconnaissance geologic map and digital data for the Yukon-Koyukuk basin, Alaska - (Integrated digital geologic map databases of the United States): U.S. Geological Survey Scientifi 2152Kcs Offshore calcareous sandstone, siltstone, and shale Cretaceous Fine- to coarse-grained, moderately to highly calcareous, turbiditic sandstone interbedded with dark-gray shale and siltstone. The sandstone occurs in beds 20 to 40 inches (50 to 100 centimeters) thick grading upward into finely cross-laminated, muscovPatton, W.W., Jr., Wilson, F.H., Labay, K.A., and Shew, Nora, in prep., Reconnaissance geologic map and digital data for the Yukon-Koyukuk basin, Alaska - (Integrated digital geologic map databases of the United States): U.S. Geological Survey Scientifi 2170 Ungalik Conglomerate Obsolete map unit 2180Kvg Volcanic-clast graywacke and mudstone Cretaceous Hard, fine-grained to conglomeratic, locally tuffaceous, graywacke and dark-gray finely laminated mudstone. The graywacke is composed of matrix-supported clasts of intermediate and mafic volcanic and intrusive rocks and chert. Clasts of quartz and of mePatton, W.W., Jr., Wilson, F.H., Labay, K.A., and Shew, Nora, in prep., Reconnaissance geologic map and digital data for the Yukon-Koyukuk basin, Alaska - (Integrated digital geologic map databases of the United States): U.S. Geological Survey Scientifi 2181Kvm Volcanic graywacke and conglomerate early Late or late Early Cretaceous?) Poorly sorted, fine- to coarse-grained graywacke, sandstone, grit, and pebble- to cobble conglomerate composed chiefly of volcanic rock and chert detritus in the Medfra and Ophir quadrangles (Patton and others, 1980; Chapman and others, 1985)). ContainsWilson, F.H., Dover, J.H., Bradley, D.C., Weber, F.R., Bundtzen, T.K., and Haeussler, P.J., 1998, Geologic map of Central (Interior) Alaska: U.S. Geological Survey Open-File Report 98-133, 3 sheets, scale 1:500,000, 63 p. pamphlet, 13 p. appendix. 2182Kgc Volcanic graywacke and conglomerate Early Cretaceous? Poorly sorted fine- to coarse-grained graywacke sandstone, grit, and pebble to cobble conglomerate composed chiefly of volcanic rock and chert detritus. Interbedded dark mudstone. Unit is tentatively assigned an Early Cretaceous age. It locally containPatton, W.W., Jr., Wilson, F.H., Labay, K.A., and Shew, Nora, in prep., Reconnaissance geologic map and digital data for the Yukon-Koyukuk basin, Alaska - (Integrated digital geologic map databases of the United States): U.S. Geological Survey Scientifi 2210Krd Rhyolite, dacite, and trachyte lava flows and volcaniclastic rocks Late Cretaceous Rhyolite, dacite, and trachyte flows and crystal and lithic tuffs, felsic ash-fall tuffs, tuffaceous graywacke, and volcanic conglomerate. One K/Ar isotopic determination from this unit gave a cooling age of 87 Ma Patton, W.W., Jr., Wilson, F.H., Labay, K.A., and Shew, Nora, in prep., Reconnaissance geologic map and digital data for the Yukon-Koyukuk basin, Alaska - (Integrated digital geologic map databases of the United States): U.S. Geological Survey Scientifi 2260Kvl Volcanic rocks Late Cretaceous Largely dacite, andesite, and basalt and subordinate andesitic to basaltic subvolcanic rocks. Ranges from flows, including agglomerate, to tuff and also dikes and sills; all are variably hydrothermally(?) altered. Subvolcanic rocks are chiefly found inWilson, F.H., Dover, J.H., Bradley, D.C., Weber, F.R., Bundtzen, T.K., and Haeussler, P.J., 1998, Geologic map of Central (Interior) Alaska: U.S. Geological Survey Open-File Report 98-133, 3 sheets, scale 1:500,000, 63 p. pamphlet, 13 p. appendix. 2320Ktg Tuff, volcanic graywacke, and mudstone Early Cretaceous Chiefly crystal and lithic tuffs and volcanic graywacke interbedded with laminated mudstone. Tuffs and graywacke characterized by abundant potassium feldspar crystals and potassium-rich volcanic rocks fragments. Unit contains rare mafic and intermediaPatton, W.W., Jr., Wilson, F.H., Labay, K.A., and Shew, Nora, in prep., Reconnaissance geologic map and digital data for the Yukon-Koyukuk basin, Alaska - (Integrated digital geologic map databases of the United States): U.S. Geological Survey Scientifi 2330Kv Andesite and basalt lava flows and volcaniclastic rocks Early Cretaceous Flows of andesite and basalt, interbedded with tuff, tuff breccia, agglomerate, volcanic conglomerate, and volcanic graywacke. Flows typically have phenocrysts of plagioclase and pyroxene set in a matrix of devitrified glass, altered plagioclase micrPatton, W.W., Jr., Wilson, F.H., Labay, K.A., and Shew, Nora, in prep., Reconnaissance geologic map and digital data for the Yukon-Koyukuk basin, Alaska - (Integrated digital geologic map databases of the United States): U.S. Geological Survey Scientifi 2335Kbd Spilitic basalt and diabase Early Cretaceous Fine-grained, amygdaloidal, spilitic pillow basalt flows and medium- to coarse-grained spilitic diabase intrusive rocks. Contains subordinate andesitic and basaltic tuffs. Appears to overlie unit Kv and to underlie unit Krd Patton, W.W., Jr., Wilson, F.H., Labay, K.A., and Shew, Nora, in prep., Reconnaissance geologic map and digital data for the Yukon-Koyukuk basin, Alaska - (Integrated digital geologic map databases of the United States): U.S. Geological Survey Scientifi 2336Kft Shoshonitic tuffs and lava flows Early Cretaceous Lithic tuffs, pillowed andesite flows, diabase, and volcanic conglomerate of shoshonitic composition, characterized chemically by very high K20, Rb, and Ba contents and low TiO2 content. Tuffs consists of coarse-grained volcanic rock fragments, crystalPatton, W.W., Jr., Wilson, F.H., Labay, K.A., and Shew, Nora, in prep., Reconnaissance geologic map and digital data for the Yukon-Koyukuk basin, Alaska - (Integrated digital geologic map databases of the United States): U.S. Geological Survey Scientifi 2410Kgu Granitic rocks of uncertain affinities Cretaceous? Medium to coarse-grained granitic intrusive and hypabyssal rocks Patton, W.W., Jr., Wilson, F.H., Labay, K.A., and Shew, Nora, in prep., Reconnaissance geologic map and digital data for the Yukon-Koyukuk basin, Alaska - (Integrated digital geologic map databases of the United States): U.S. Geological Survey Scientifi 2420Kgd Granodiorite and granite Late Cretaceous Generally fine- to medium-grained equigranular, but locally porphyritic, hornblende-biotite granodiorite, and alaskitic biotite granite. Locally includes tonalite and quartz monzodiorite. K/Ar isotopic cooling ages range from 89 to 78 Ma Patton, W.W., Jr., Wilson, F.H., Labay, K.A., and Shew, Nora, in prep., Reconnaissance geologic map and digital data for the Yukon-Koyukuk basin, Alaska - (Integrated digital geologic map databases of the United States): U.S. Geological Survey Scientifi 2440Kmum Mafic and ultramafic rocks Cretaceous Gabbro, diorite, serpentinite, and mafic volcaniclastic rocks. Ranges from small, structurally bounded, pervasively sheared, discordant bodies of serpentinized ultramafic rocks wholly enclosed in pelitic schist in the Anchorage quadrangle (Winkler (1992Wilson, F.H., Dover, J.H., Bradley, D.C., Weber, F.R., Bundtzen, T.K., and Haeussler, P.J., 1998, Geologic map of Central (Interior) Alaska: U.S. Geological Survey Open-File Report 98-133, 3 sheets, scale 1:500,000, 63 p. pamphlet, 13 p. appendix. 2450Kgd Granodiorite and granite Late Cretaceous Generally fine- to medium-grained equigranular, but locally porphyritic, hornblende-biotite granodiorite, and alaskitic biotite granite. Locally includes tonalite and quartz monzodiorite. K/Ar isotopic cooling ages range from 89 to 78 Ma Patton, W.W., Jr., Wilson, F.H., Labay, K.A., and Shew, Nora, in prep., Reconnaissance geologic map and digital data for the Yukon-Koyukuk basin, Alaska - (Integrated digital geologic map databases of the United States): U.S. Geological Survey Scientifi 2460Ksm Syenite and monzonite Late Cretaceous Consists chiefly of hornblende syenite, biotite-hornblende monzonite, and monzodiorite, and lesser amounts of biotite diorite and biotite quartz monzonite. One K/Ar isotopic determination yielded a cooling age of 76 Ma Patton, W.W., Jr., Wilson, F.H., Labay, K.A., and Shew, Nora, in prep., Reconnaissance geologic map and digital data for the Yukon-Koyukuk basin, Alaska - (Integrated digital geologic map databases of the United States): U.S. Geological Survey Scientifi 2470Kg Granitic rocks Cretaceous Largely granitic, but range from tourmaline-bearing granite to diorite. Intrusions range from dikes and sills, to small and large plutons. Widely distributed includes granite plutons in the Mount Hayes quadrangle, and quartz monzonite and granodiorite Wilson, F.H., Dover, J.H., Bradley, D.C., Weber, F.R., Bundtzen, T.K., and Haeussler, P.J., 1998, Geologic map of Central (Interior) Alaska: U.S. Geological Survey Open-File Report 98-133, 3 sheets, scale 1:500,000, 63 p. pamphlet, 13 p. appendix. 2510Kmum Mafic and ultramafic rocks Cretaceous Gabbro, diorite, serpentinite, and mafic volcaniclastic rocks. Ranges from small, structurally bounded, pervasively sheared, discordant bodies of serpentinized ultramafic rocks wholly enclosed in pelitic schist in the Anchorage quadrangle (Winkler (1992Wilson, F.H., Dover, J.H., Bradley, D.C., Weber, F.R., Bundtzen, T.K., and Haeussler, P.J., 1998, Geologic map of Central (Interior) Alaska: U.S. Geological Survey Open-File Report 98-133, 3 sheets, scale 1:500,000, 63 p. pamphlet, 13 p. appendix. 2515Kgr Granite and granodiorite Early Cretaceous Unit consists chiefly of biotite and muscovite-biotite granite and granodiorite. K/Ar isotopic cooling ages range from 112 to 96 Ma and two U/Pb zircon analyses give crystallization ages of 112 and 109 Ma Patton, W.W., Jr., Wilson, F.H., Labay, K.A., and Shew, Nora, in prep., Reconnaissance geologic map and digital data for the Yukon-Koyukuk basin, Alaska - (Integrated digital geologic map databases of the United States): U.S. Geological Survey Scientifi 2530Kgr Granite and granodiorite Early Cretaceous Unit consists chiefly of biotite and muscovite-biotite granite and granodiorite. K/Ar isotopic cooling ages range from 112 to 96 Ma and two U/Pb zircon analyses give crystallization ages of 112 and 109 Ma Patton, W.W., Jr., Wilson, F.H., Labay, K.A., and Shew, Nora, in prep., Reconnaissance geologic map and digital data for the Yukon-Koyukuk basin, Alaska - (Integrated digital geologic map databases of the United States): U.S. Geological Survey Scientifi 2535Knsy Syenite, monzonite, and nepheline syenite; nepheline syenite unit Early Cretaceous large bodies of nepheline syenite and related rocks shown separately on the map Patton, W.W., Jr., Wilson, F.H., Labay, K.A., and Shew, Nora, in prep., Reconnaissance geologic map and digital data for the Yukon-Koyukuk basin, Alaska - (Integrated digital geologic map databases of the United States): U.S. Geological Survey Scientifi 2545Ksy Syenite, monzonite, and nepheline syenite Early Cretaceous Unit composed of syenite, monzonite, and subordinate quartz monzonite, monzodiorite, quartz syenite, and nepheline syenite and related mafic alkaline rocks including malignite, ijolite, shonkinite, and pyroxenite. K/Ar isotopic cooling ages from units Patton, W.W., Jr., Wilson, F.H., Labay, K.A., and Shew, Nora, in prep., Reconnaissance geologic map and digital data for the Yukon-Koyukuk basin, Alaska - (Integrated digital geologic map databases of the United States): U.S. Geological Survey Scientifi 2812KJwc Wilber Creek flysch and Wolverine quartzite, undivided Early Cretaceous or Late Jurassic Locally mapped unit consisting of units KJwc and Kwcf in the Tanana quadrangle Wilson, F.H., Dover, J.H., Bradley, D.C., Weber, F.R., Bundtzen, T.K., and Haeussler, P.J., 1998, Geologic map of Central (Interior) Alaska: U.S. Geological Survey Open-File Report 98-133, 3 sheets, scale 1:500,000, 63 p. pamphlet, 13 p. appendix. 2815KJw Wolverine quartzite Early Cretaceous or Late Jurassic Light- to dark-gray, very fine- to medium-grained, well-sorted, quartzite containing interbedded black to dark-gray shale and medium-light- to medium-gray siltstone. Rare coquina-like beds contain poorly preserved fragments of Buchia and other fossils tWilson, F.H., Dover, J.H., Bradley, D.C., Weber, F.R., Bundtzen, T.K., and Haeussler, P.J., 1998, Geologic map of Central (Interior) Alaska: U.S. Geological Survey Open-File Report 98-133, 3 sheets, scale 1:500,000, 63 p. pamphlet, 13 p. appendix. 2816KJw Wolverine quartzite Early Cretaceous or Late Jurassic Light- to dark-gray, very fine- to medium-grained, well-sorted, quartzite containing interbedded black to dark-gray shale and medium-light- to medium-gray siltstone. Rare coquina-like beds contain poorly preserved fragments of Buchia and other fossils tWilson, F.H., Dover, J.H., Bradley, D.C., Weber, F.R., Bundtzen, T.K., and Haeussler, P.J., 1998, Geologic map of Central (Interior) Alaska: U.S. Geological Survey Open-File Report 98-133, 3 sheets, scale 1:500,000, 63 p. pamphlet, 13 p. appendix. 2817KJw Wolverine quartzite Early Cretaceous or Late Jurassic Light- to dark-gray, very fine- to medium-grained, well-sorted, quartzite containing interbedded black to dark-gray shale and medium-light- to medium-gray siltstone. Rare coquina-like beds contain poorly preserved fragments of Buchia and other fossils tWilson, F.H., Dover, J.H., Bradley, D.C., Weber, F.R., Bundtzen, T.K., and Haeussler, P.J., 1998, Geologic map of Central (Interior) Alaska: U.S. Geological Survey Open-File Report 98-133, 3 sheets, scale 1:500,000, 63 p. pamphlet, 13 p. appendix. 3380Jgt Trondhjemite and tonalite Late and Middle Jurassic Trondhjemite, tonalite, and subordinate quartz diorite, diorite, and gabbro. Trondhjemite consists of 50 to 60 percent plagioclase, 25 to 45 percent quartz, 4 to 8 percent mafic minerals (chiefly biotite and subordinate amphibole). Tonalite has 50 to Patton, W.W., Jr., Wilson, F.H., Labay, K.A., and Shew, Nora, in prep., Reconnaissance geologic map and digital data for the Yukon-Koyukuk basin, Alaska - (Integrated digital geologic map databases of the United States): U.S. Geological Survey Scientifi 3496MzPzumMafic-ultramfic complexes Mesozoic and Paleozoic? The complexes consist of: 1) a cumulate magmatic suite composed of interlayered dunite, wehrlite, olivine clinopyroxenite, and gabbro, 2) a mantle suite composed of harzburgite, dunite, and minor clinopyoxenite, and 3) a metamorphic sole consisting of a Patton, W.W., Jr., Wilson, F.H., Labay, K.A., and Shew, Nora, in prep., Reconnaissance geologic map and digital data for the Yukon-Koyukuk basin, Alaska - (Integrated digital geologic map databases of the United States): U.S. Geological Survey Scientifi 3497MzPzumMafic-ultramfic complexes Mesozoic and Paleozoic? The complexes consist of: 1) a cumulate magmatic suite composed of interlayered dunite, wehrlite, olivine clinopyroxenite, and gabbro, 2) a mantle suite composed of harzburgite, dunite, and minor clinopyoxenite, and 3) a metamorphic sole consisting of a Patton, W.W., Jr., Wilson, F.H., Labay, K.A., and Shew, Nora, in prep., Reconnaissance geologic map and digital data for the Yukon-Koyukuk basin, Alaska - (Integrated digital geologic map databases of the United States): U.S. Geological Survey Scientifi 3498MzPzumMafic-ultramfic complexes Mesozoic and Paleozoic? The complexes consist of: 1) a cumulate magmatic suite composed of interlayered dunite, wehrlite, olivine clinopyroxenite, and gabbro, 2) a mantle suite composed of harzburgite, dunite, and minor clinopyoxenite, and 3) a metamorphic sole consisting of a Patton, W.W., Jr., Wilson, F.H., Labay, K.A., and Shew, Nora, in prep., Reconnaissance geologic map and digital data for the Yukon-Koyukuk basin, Alaska - (Integrated digital geologic map databases of the United States): U.S. Geological Survey Scientifi 3851JMc Chert, cherty tuff, argillite, crystal-lithic tuff, volcanic breccia, and conglomerate Jurassic? to Mississippian Chiefly banded radiolarian chert interbedded with argillite, cherty tuff, fine- to coarse-grained crystal and lithic tuff, and volcanic breccia and conglomerate. Breccia and conglomerate are composed of poorly sorted clasts of mafic volcanic rocks andPatton, W.W., Jr., Wilson, F.H., Labay, K.A., and Shew, Nora, in prep., Reconnaissance geologic map and digital data for the Yukon-Koyukuk basin, Alaska - (Integrated digital geologic map databases of the United States): U.S. Geological Survey Scientifi 4032Trs Spiculite and sandy limestone Late Triassic Composed of quartz-carbonate sandstone and conglomerate in the lower part of unit and spiculitic chert in the upper part. Sandstone and conglomerate consist of detrital carbonate, quartz, and chert clasts, and calcareous fossil debris. Spiculite is comPatton, W.W., Jr., Wilson, F.H., Labay, K.A., and Shew, Nora, in prep., Reconnaissance geologic map and digital data for the Yukon-Koyukuk basin, Alaska - (Integrated digital geologic map databases of the United States): U.S. Geological Survey Scientifi 4340Trc Carbonatite Triassic Intensely magnetic dolomite-calcite-magnetite-apatite-rich rock in two sill-like bodies in the southeastern Tanana quadrangle. 40Ar/39Ar age of about 200 Ma reported on contact metamorphic mica reported by Reifenstuhl and others (1998) and interpreted aWilson, F.H., Dover, J.H., Bradley, D.C., Weber, F.R., Bundtzen, T.K., and Haeussler, P.J., 1998, Geologic map of Central (Interior) Alaska: U.S. Geological Survey Open-File Report 98-133, 3 sheets, scale 1:500,000, 63 p. pamphlet, 13 p. appendix. 4880Mzi Intrusive rocks Mesozoic? Undated parts of the Alaska-Aleutian Range batholith in the Tyonek quadrangle. Chiefly quartz diorite, diorite, and gabbro (Reed and Elliott, 1970) Wilson, F.H., Dover, J.H., Bradley, D.C., Weber, F.R., Bundtzen, T.K., and Haeussler, P.J., 1998, Geologic map of Central (Interior) Alaska: U.S. Geological Survey Open-File Report 98-133, 3 sheets, scale 1:500,000, 63 p. pamphlet, 13 p. appendix. 5012TrPs Sedimentary rocks, undivided Triassic to Permian Dominantly dark gray, typically phyllitic, siliceous to carbonaceous argillite and shale, with subordinate but characteristic clast-supported chert-rich conglomerate, greenish-gray chert, tuffaceous volcaniclastic rocks, yellowish- to reddish-brown highlWilson, F.H., Dover, J.H., Bradley, D.C., Weber, F.R., Bundtzen, T.K., and Haeussler, P.J., 1998, Geologic map of Central (Interior) Alaska: U.S. Geological Survey Open-File Report 98-133, 3 sheets, scale 1:500,000, 63 p. pamphlet, 13 p. appendix. 5020TrMts Tozitna assemblage (north): Sedimentary rocks Triassic to Mississippian Chert, metachert, metatuff, quartzite, phyllite, and other associated incipiently metamorphosed sedimentary rocks; includes basalt and amygdaloidal pillow basalt in places. Corresponds to the Rampart Group of Brosge and others (1969) in the Tanana quadrWilson, F.H., Dover, J.H., Bradley, D.C., Weber, F.R., Bundtzen, T.K., and Haeussler, P.J., 1998, Geologic map of Central (Interior) Alaska: U.S. Geological Survey Open-File Report 98-133, 3 sheets, scale 1:500,000, 63 p. pamphlet, 13 p. appendix. 5021TrMg Graywacke, grit, and argillite Triassic? to Mississippian? Fine- to medium-grained, commonly calcareous graywacke and granule conglomerate, which contain clasts of chert, shale, argillite, and volcanic rocks. Graywacke and conglomerate are interbedded with argillite. Unit contains microfossils and bryozoan anPatton, W.W., Jr., Wilson, F.H., Labay, K.A., and Shew, Nora, in prep., Reconnaissance geologic map and digital data for the Yukon-Koyukuk basin, Alaska - (Integrated digital geologic map databases of the United States): U.S. Geological Survey Scientifi 5112TrMicaInnoko assemblage: Chert, argillite, and volcaniclastic rocks Triassic to Mississippian Dominantly medium-dark- to dark-gray, thin-banded, bedded radiolarian-bearing chert having thin interbeds of slaty argillaceous rocks, including argillite, slate, and phyllite. Also includes subordinate intermediate to basaltic volcanic and volcaniclastWilson, F.H., Dover, J.H., Bradley, D.C., Weber, F.R., Bundtzen, T.K., and Haeussler, P.J., 1998, Geologic map of Central (Interior) Alaska: U.S. Geological Survey Open-File Report 98-133, 3 sheets, scale 1:500,000, 63 p. pamphlet, 13 p. appendix. 5113JPztm Tozitna assemblage (south): Mafic and ultramafic rocks, undivided Jurassic? and/or Paleozoic? Gabbro sills and subordinate quartz diorite, quartz monzonite, and pyroxenite. Undated; age and assignment to the Tozitna assemblage based on lithologic associations and regional comparisons. Corresponds to informal Pzmi unit of Puchner (1984) in westeWilson, F.H., Dover, J.H., Bradley, D.C., Weber, F.R., Bundtzen, T.K., and Haeussler, P.J., 1998, Geologic map of Central (Interior) Alaska: U.S. Geological Survey Open-File Report 98-133, 3 sheets, scale 1:500,000, 63 p. pamphlet, 13 p. appendix. 5120MzPzi Intrusive and volcanic rocks, undivided Mesozoic or Paleozoic Granodiorite of Rainbow Mountain in the Mount Hayes quadrangle (unit grrm, Nokleberg and others, 1992a), diorite in the Circle and Bid Delta quadrangles (unit MzPzd, Foster and others, 1983; unit Pzd, Weber and others, 1978), and gabbro and quartz dioritWilson, F.H., Dover, J.H., Bradley, D.C., Weber, F.R., Bundtzen, T.K., and Haeussler, P.J., 1998, Geologic map of Central (Interior) Alaska: U.S. Geological Survey Open-File Report 98-133, 3 sheets, scale 1:500,000, 63 p. pamphlet, 13 p. appendix. 5130JTrtmuTozitna assemblage (north): Mafic and ultramafic rocks Jurassic? to Triassic Diabase, gabbro, leucogabbro, and greenstone; ultramafic rocks include serpentinized peridotite, harzburgite, and werhlite. Locally, may include minor associated sedimentary rocks. Tentative age range based on K-Ar age of 210+/-6 Ma reported by Brosge Wilson, F.H., Dover, J.H., Bradley, D.C., Weber, F.R., Bundtzen, T.K., and Haeussler, P.J., 1998, Geologic map of Central (Interior) Alaska: U.S. Geological Survey Open-File Report 98-133, 3 sheets, scale 1:500,000, 63 p. pamphlet, 13 p. appendix. 5131TrMbc Pillow basalt, chert, and minor agglomerate Triassic? to Mississippian? Altered aphanitic and porphyritic pillow basalt. Phenocrysts in the porphyritic basalt are composed chiefly of olivine and pyroxene. Basalt is interlayered with chert and subordinate beds of agglomerate containing clasts of basalt and chert. Chert conPatton, W.W., Jr., Wilson, F.H., Labay, K.A., and Shew, Nora, in prep., Reconnaissance geologic map and digital data for the Yukon-Koyukuk basin, Alaska - (Integrated digital geologic map databases of the United States): U.S. Geological Survey Scientifi 5132JMtru Tozitna assemblage (north): Greenstone, chert, and ultramafic rocks, undivided Jurassic? to Mississippian? Poorly dated spilitic basalt and diabase largely altered to greenstone. Locally, includes minor sedimentary rocks, generally low metamorphic grade cataclastic assemblage of generally dark gray chert and siliceous argillite. Also includes subordinate voWilson, F.H., Dover, J.H., Bradley, D.C., Weber, F.R., Bundtzen, T.K., and Haeussler, P.J., 1998, Geologic map of Central (Interior) Alaska: U.S. Geological Survey Open-File Report 98-133, 3 sheets, scale 1:500,000, 63 p. pamphlet, 13 p. appendix. 5133JMtu Tozitna assemblage (south): Mafic, ultramafic, and sedimentary rocks, undivided Jurassic to Mississippian Basalt, gabbro, diabase, basaltic tuff, and chert. May include minor ultramafic rocks and other associated low metamorphic grade metasedimentary rocks in the Nulato, Ophir, and Ruby quadrangles that resemble the Tozitna assemblage north of the Kaltag faWilson, F.H., Dover, J.H., Bradley, D.C., Weber, F.R., Bundtzen, T.K., and Haeussler, P.J., 1998, Geologic map of Central (Interior) Alaska: U.S. Geological Survey Open-File Report 98-133, 3 sheets, scale 1:500,000, 63 p. pamphlet, 13 p. appendix. 5140JDv Altered basalt, gabbro, chert, argillaceous rocks, tuff, graywacke, and carbonate rocks Jurassic to Devonian Variably altered and metamorphosed flows and shallow intrusives of basalt, diabase, and gabbro interbedded with varying proportions of chert, argillite, slate, phyllite, volcaniclastic rocks, graywacke, and carbonate rocks. The basalt, diabase, and gabbPatton, W.W., Jr., Wilson, F.H., Labay, K.A., and Shew, Nora, in prep., Reconnaissance geologic map and digital data for the Yukon-Koyukuk basin, Alaska - (Integrated digital geologic map databases of the United States): U.S. Geological Survey Scientifi 5145KJm Melange Early Cretaceous? and Jurassic Melange consists of blocks of carbonate rocks, chert, metagraywacke, and altered mafic volcanic and intrusive rocks in a matrix of phyllite. Within the melange unit the large blocks of carbonate rocks from units |ca and |cr and altered basalt, diabasePatton, W.W., Jr., Wilson, F.H., Labay, K.A., and Shew, Nora, in prep., Reconnaissance geologic map and digital data for the Yukon-Koyukuk basin, Alaska - (Integrated digital geologic map databases of the United States): U.S. Geological Survey Scientifi 5150MzPzumMafic-ultramfic complexes Mesozoic and Paleozoic? The complexes consist of: 1) a cumulate magmatic suite composed of interlayered dunite, wehrlite, olivine clinopyroxenite, and gabbro, 2) a mantle suite composed of harzburgite, dunite, and minor clinopyoxenite, and 3) a metamorphic sole consisting of a Patton, W.W., Jr., Wilson, F.H., Labay, K.A., and Shew, Nora, in prep., Reconnaissance geologic map and digital data for the Yukon-Koyukuk basin, Alaska - (Integrated digital geologic map databases of the United States): U.S. Geological Survey Scientifi 5190MzPzumMafic-ultramfic complexes Mesozoic and Paleozoic? The complexes consist of: 1) a cumulate magmatic suite composed of interlayered dunite, wehrlite, olivine clinopyroxenite, and gabbro, 2) a mantle suite composed of harzburgite, dunite, and minor clinopyoxenite, and 3) a metamorphic sole consisting of a Patton, W.W., Jr., Wilson, F.H., Labay, K.A., and Shew, Nora, in prep., Reconnaissance geologic map and digital data for the Yukon-Koyukuk basin, Alaska - (Integrated digital geologic map databases of the United States): U.S. Geological Survey Scientifi 5208TPza Amphibolite facies metamorphic rocks Earliest Tertiary to Paleozoic Dominantly medium- to medium-dark-gray garnetiferous quartz-mica schist and amphibolite, but includes slate and shale in the Livengood quadrangle. Locally has gneissic texture. Minor marble and very minor quartzite occur in unit in the Tanana quadranglWilson, F.H., Dover, J.H., Bradley, D.C., Weber, F.R., Bundtzen, T.K., and Haeussler, P.J., 1998, Geologic map of Central (Interior) Alaska: U.S. Geological Survey Open-File Report 98-133, 3 sheets, scale 1:500,000, 63 p. pamphlet, 13 p. appendix. 5241MzZma Metabasite Mesozoic? to Proterozoic? Varies from thinly layered greenschist to more massively layered greenstone bodies representing altered mafic and intermediate volcanic and shallow intrusive rocks. The characteristic mineral are chlorite, albite, actinolite, and epidote. Unit may inclPatton, W.W., Jr., Wilson, F.H., Labay, K.A., and Shew, Nora, in prep., Reconnaissance geologic map and digital data for the Yukon-Koyukuk basin, Alaska - (Integrated digital geologic map databases of the United States): U.S. Geological Survey Scientifi 5242MzZmr Metabasite Mesozoic? to Proterozoic? Massive greenstone to thinly layered greenschist bodies that probably represent metamorphosed mafic to ultramafic intrusive rocks and mafic to intermediate flows and tuffs. Unit is intercalated with with units PzZsr Pzcr, and Dgnr. Patton, W.W., Jr., Wilson, F.H., Labay, K.A., and Shew, Nora, in prep., Reconnaissance geologic map and digital data for the Yukon-Koyukuk basin, Alaska - (Integrated digital geologic map databases of the United States): U.S. Geological Survey Scientifi 5243MzZms Metabasite Mesozoic? to Proterozoic? Greenstone and greenschist bodies representing altered mafic and intermediate volcanic and intrusive rocks Patton, W.W., Jr., Wilson, F.H., Labay, K.A., and Shew, Nora, in prep., Reconnaissance geologic map and digital data for the Yukon-Koyukuk basin, Alaska - (Integrated digital geologic map databases of the United States): U.S. Geological Survey Scientifi 5280JDv Altered basalt, gabbro, chert, argillaceous rocks, tuff, graywacke, and carbonate rocks Jurassic to Devonian Variably altered and metamorphosed flows and shallow intrusives of basalt, diabase, and gabbro interbedded with varying proportions of chert, argillite, slate, phyllite, volcaniclastic rocks, graywacke, and carbonate rocks. The basalt, diabase, and gabbPatton, W.W., Jr., Wilson, F.H., Labay, K.A., and Shew, Nora, in prep., Reconnaissance geologic map and digital data for the Yukon-Koyukuk basin, Alaska - (Integrated digital geologic map databases of the United States): U.S. Geological Survey Scientifi 5285Pzrmi Ruby metamorphic complex -- Metamorphosed mafic igneous rocks Paleozoic? Metamorphosed mafic igneous rocks, ranging from metagabbro and metadiabase to greenstone, amphibolite, and garnet amphibolite. Variable intensity of sheared within unit. Unit Pzm of Dover (unpublished mapping, 1997), not mapped separately by Chapman anWilson, F.H., Dover, J.H., Bradley, D.C., Weber, F.R., Bundtzen, T.K., and Haeussler, P.J., 1998, Geologic map of Central (Interior) Alaska: U.S. Geological Survey Open-File Report 98-133, 3 sheets, scale 1:500,000, 63 p. pamphlet, 13 p. appendix. 5295MzZfm Metabasite (MzZma) and felsic schist (Df), undivided Mesozoic? to Proterozoic? Metabasite (MzZma) and felsic schist (Df), undivided Patton, W.W., Jr., Wilson, F.H., Labay, K.A., and Shew, Nora, in prep., Reconnaissance geologic map and digital data for the Yukon-Koyukuk basin, Alaska - (Integrated digital geologic map databases of the United States): U.S. Geological Survey Scientifi 5310DCd East Fork Hills Formation Devonian to Cambrian Deep-water deposits of finely laminated limestone and dolomitic limestone. Subordinate chert and siliceous siltstone. Formation was originally assigned an Ordovician to Devonian age on the basis of a sparse conodont fauna (Dutro and Patton, 1982. More Patton, W.W., Jr., Wilson, F.H., Labay, K.A., and Shew, Nora, in prep., Reconnaissance geologic map and digital data for the Yukon-Koyukuk basin, Alaska - (Integrated digital geologic map databases of the United States): U.S. Geological Survey Scientifi 5320Pzcs Carbonate rocks Paleozoic Chiefly massively bedded light gray to tan dolomitic and calcareous marble. Locally interbedded black to dark gray calcareous marble and subordinate impure marble and calcareous schist. Unit locally contains an abundant conodont fauna of Ordovician to Patton, W.W., Jr., Wilson, F.H., Labay, K.A., and Shew, Nora, in prep., Reconnaissance geologic map and digital data for the Yukon-Koyukuk basin, Alaska - (Integrated digital geologic map databases of the United States): U.S. Geological Survey Scientifi 5321PzZus Pelitic schist, calc schist, and quartzite (PzZss) and carbonate rocks (Pzcs), undivided Paleozoic and Proterozoic? Scattered exposures along the western edge of the map area extending from the Norton Bay quadrangle to the southwestern part of the Selawik quadrangle 5322PzZss Pelitic schist, calc schist, and quartzite Paleozoic and Proterozoic? Quartz-muscovite-graphite schist, calc schist, quartzofeldspathic schist, phyllite, and quartzite. Unit is locally interlayered with unit |cs and is therefore, at least in part, Paleozoic in age. Some of the unit may be as old as Proterozoic. Samples Patton, W.W., Jr., Wilson, F.H., Labay, K.A., and Shew, Nora, in prep., Reconnaissance geologic map and digital data for the Yukon-Koyukuk basin, Alaska - (Integrated digital geologic map databases of the United States): U.S. Geological Survey Scientifi 5340Pzcr Carbonate rocks Paleozoic Gray to white, partly to wholly recrystallized limestone, marble, dark-gray dolomitic marble, and impure schistose limestone. Unit occurs in layers as much as 25m thick intercalated with quartz-mica schist, mica schist, graphitic schist, metabasite, andWilson, F.H., Dover, J.H., Bradley, D.C., Weber, F.R., Bundtzen, T.K., and Haeussler, P.J., 1998, Geologic map of Central (Interior) Alaska: U.S. Geological Survey Open-File Report 98-133, 3 sheets, scale 1:500,000, 63 p. pamphlet, 13 p. appendix. 5410Pzvs Volcanic and sedimentary rocks late or middle Paleozoic Dark-greenish-gray mafic volcanic rocks and interbeds of black phyllite, chert-pebble conglomerate, light-green tuff, and graywacke (Reed and Nelson, 1980). Volcanic rocks include pillow basalt, breccia agglomerate, tuff, and massive basalt flows. DistWilson, F.H., Dover, J.H., Bradley, D.C., Weber, F.R., Bundtzen, T.K., and Haeussler, P.J., 1998, Geologic map of Central (Interior) Alaska: U.S. Geological Survey Open-File Report 98-133, 3 sheets, scale 1:500,000, 63 p. pamphlet, 13 p. appendix. 5521MzZrc Complex of the Reindeer Hills Mesozoic to Proterozoic? Undivided assemblage of interlayered impure marble, quartz-mica schist, and quartzite intruded by aplite and amphibolite dikes. Includes some ductily deformed metasomatized contact marble with biotite- and epidote-rich bands. Field data are insufficiePatton, W.W., Jr., Wilson, F.H., Labay, K.A., and Shew, Nora, in prep., Reconnaissance geologic map and digital data for the Yukon-Koyukuk basin, Alaska - (Integrated digital geologic map databases of the United States): U.S. Geological Survey Scientifi 5525Pzca Carbonate rocks Paleozoic Ranges from light gray to white partly recrystallized limestone to coarsely crystalline marble. Dark finely crystalline dolomitic marble. Interbedded calc schist, chloritic schist, and quartzite in subordinate amounts. Unit ranges in age from OrdoviciPatton, W.W., Jr., Wilson, F.H., Labay, K.A., and Shew, Nora, in prep., Reconnaissance geologic map and digital data for the Yukon-Koyukuk basin, Alaska - (Integrated digital geologic map databases of the United States): U.S. Geological Survey Scientifi 5542MzPzq Quartzite, grit, argillite, and quartz-mica schist early Paleozoic and Proterozoic? Mixed assemblage of laminated fine-to coarse-grained quartzite, grit, and argillite grading upward into very fine-grained quartzite, argillite, phyllite, and chert. In southeast corner of Medfra quadrangle unit is metamorphosed to greenschist facies comPatton, W.W., Jr., Wilson, F.H., Labay, K.A., and Shew, Nora, in prep., Reconnaissance geologic map and digital data for the Yukon-Koyukuk basin, Alaska - (Integrated digital geologic map databases of the United States): U.S. Geological Survey Scientifi 5560Pzpa Phyllite and subordinate metagraywacke Paleozoic? Dark phyllite and minor metagraywacke that have a penetrative fabric ranging from slaty cleavage to weakly schistose. Unit locally contains slices of little deformed shallow-water Devonian carbonate rocks that are enveloped in basalt flows and debris-flPatton, W.W., Jr., Wilson, F.H., Labay, K.A., and Shew, Nora, in prep., Reconnaissance geologic map and digital data for the Yukon-Koyukuk basin, Alaska - (Integrated digital geologic map databases of the United States): U.S. Geological Survey Scientifi 5561Pzpr Phyllite Paleozoic? Phyllite and subordinate fine-grained metagraywacke cut by abundant vein quartz. The phyllite and metagraywacke are overprinted by a low-grade penetrative metamorphic fabric, but turbidite features, such as sole marks and graded bedding, are locally disPatton, W.W., Jr., Wilson, F.H., Labay, K.A., and Shew, Nora, in prep., Reconnaissance geologic map and digital data for the Yukon-Koyukuk basin, Alaska - (Integrated digital geologic map databases of the United States): U.S. Geological Survey Scientifi 5565Pzg Metagraywacke and subordinate phyllite Paleozoic? Fine- to medium-grained metagraywacke and metasiltstone composed chiefly of quartz and chert clasts, but in places containing a significant component of volcanic rock and feldspar clasts. Overprinted by low-grade penetrative metamorphic fabric, but turPatton, W.W., Jr., Wilson, F.H., Labay, K.A., and Shew, Nora, in prep., Reconnaissance geologic map and digital data for the Yukon-Koyukuk basin, Alaska - (Integrated digital geologic map databases of the United States): U.S. Geological Survey Scientifi 5615PDms Sedimentary rocks Permian? to Devonian? Indeterminate or poorly identified units in Livengood quadrangle. Black and greenish-gray siliceous slate, thinly interbedded gray chert, shaly chert, and minor breccia, siliceous, locally sandy siltstone displaying turbiditic sedimentary structures, reWilson, F.H., Dover, J.H., Bradley, D.C., Weber, F.R., Bundtzen, T.K., and Haeussler, P.J., 1998, Geologic map of Central (Interior) Alaska: U.S. Geological Survey Open-File Report 98-133, 3 sheets, scale 1:500,000, 63 p. pamphlet, 13 p. appendix. 5740Ps Sanstone, sandy limestone, and conglomerate Permian Fine- to coarse-grained sandstone, limy sandstone, sandy limestone, siltstone and shale. Sandstone ranges from clean quartz arenite to a lithic arenite containing as much as 25 percent muscovite and metamorphic rock fragments. Where unit unconformablyPatton, W.W., Jr., Wilson, F.H., Labay, K.A., and Shew, Nora, in prep., Reconnaissance geologic map and digital data for the Yukon-Koyukuk basin, Alaska - (Integrated digital geologic map databases of the United States): U.S. Geological Survey Scientifi 5745TrMg Graywacke, grit, and argillite Triassic? to Mississippian? Fine- to medium-grained, commonly calcareous graywacke and granule conglomerate, which contain clasts of chert, shale, argillite, and volcanic rocks. Graywacke and conglomerate are interbedded with argillite. Unit contains microfossils and bryozoan anPatton, W.W., Jr., Wilson, F.H., Labay, K.A., and Shew, Nora, in prep., Reconnaissance geologic map and digital data for the Yukon-Koyukuk basin, Alaska - (Integrated digital geologic map databases of the United States): U.S. Geological Survey Scientifi 6080TrDc Chert, argillite, and limestone Triassic? to Devonian Varicolored radiolarian chert, lenticular beds of fossiliferous limestone and interbedded argillite. Subordinate beds of sandy limestone, grit, and arkosic sandstone. Unit contains abundant radiolaria, condonts, and foraminifera that range in age from Patton, W.W., Jr., Wilson, F.H., Labay, K.A., and Shew, Nora, in prep., Reconnaissance geologic map and digital data for the Yukon-Koyukuk basin, Alaska - (Integrated digital geologic map databases of the United States): U.S. Geological Survey Scientifi 6522Dgnr Granitic gneiss Devonian Strongly foliated quartzofeldspathic gneiss. Consists of a coarse- to medium-grained porphyroclastic biotite-quartz-feldsparñmuscovite mylonite gneiss containing resistant augen of K-feldspar in a ductile matrix of mica, quartz, and feldspar. A U/Pb zPatton, W.W., Jr., Wilson, F.H., Labay, K.A., and Shew, Nora, in prep., Reconnaissance geologic map and digital data for the Yukon-Koyukuk basin, Alaska - (Integrated digital geologic map databases of the United States): U.S. Geological Survey Scientifi 6523Dgna Granitic gneiss Devonian Foliated gneissic granite composed of albite, potassium feldspar, quartz, muscovite, and biotite. Intruded by aplite dikes. Pluton yielded a probable Devonian U/Pb zircon crystallization age. Correlative in age with unit Dgnr in the Ruby terrane Patton, W.W., Jr., Wilson, F.H., Labay, K.A., and Shew, Nora, in prep., Reconnaissance geologic map and digital data for the Yukon-Koyukuk basin, Alaska - (Integrated digital geologic map databases of the United States): U.S. Geological Survey Scientifi 6530Mgq Globe quartzite Mississippian Light gray, massive or thinly laminated quartzite and medium- to dark-gray slate, phyllite, and laminated claystone. Unfossiliferous; age inferred on the basis of intrusion by Triassic rocks and by lithologic and stratigraphic similarity with the Keno HWilson, F.H., Dover, J.H., Bradley, D.C., Weber, F.R., Bundtzen, T.K., and Haeussler, P.J., 1998, Geologic map of Central (Interior) Alaska: U.S. Geological Survey Open-File Report 98-133, 3 sheets, scale 1:500,000, 63 p. pamphlet, 13 p. appendix. 6620DSp Paradise Fork Formation Early Devonian and Silurian Deep-water turbiditic and hemipelagic deposits of dark, thin-bedded, fissile to laminated limestone, limy shale, and siltstone. The formation has an abundant graptolite, conodont, and ostracod fauna. It was originally assigned an Early to Late SilurianPatton, W.W., Jr., Wilson, F.H., Labay, K.A., and Shew, Nora, in prep., Reconnaissance geologic map and digital data for the Yukon-Koyukuk basin, Alaska - (Integrated digital geologic map databases of the United States): U.S. Geological Survey Scientifi 6680SZa Amy Creek unit Silurian to Late Proterozoic In Livengood quadrangle were described by Weber and others (1992), consists chiefly of medium-grained gray dolostone, and light-gray, yellow-gray, or buff dolomitic mudstone, packstone, and wackestone. Coarser-grained rocks show abundant peloids and croWilson, F.H., Dover, J.H., Bradley, D.C., Weber, F.R., Bundtzen, T.K., and Haeussler, P.J., 1998, Geologic map of Central (Interior) Alaska: U.S. Geological Survey Open-File Report 98-133, 3 sheets, scale 1:500,000, 63 p. pamphlet, 13 p. appendix. 6910Dtr Troublesome unit and possibly correlative rocks Devonian? Rhythmically interbedded dark-gray to black cherty argillite to chert, and thin beds of black to gray, siliceous slate as mapped in the Livengood quadrangle. Associated with extensive mafic intrusive and extrusive rocks. Unidentified radiolaria are onlWilson, F.H., Dover, J.H., Bradley, D.C., Weber, F.R., Bundtzen, T.K., and Haeussler, P.J., 1998, Geologic map of Central (Interior) Alaska: U.S. Geological Survey Open-File Report 98-133, 3 sheets, scale 1:500,000, 63 p. pamphlet, 13 p. appendix. 6956Pzlsl Schist, phyllite, limestone, and greenstone Early Paleozoic Light- to medium-green chloritic schist, light- to medium-gray with silvery sheen phyllite, light- to medium-gray and greenish-gray, sandy in part, largely recrystallized limestone, and light- to medium-green greenstone. Schist and phyllite are partly cWilson, F.H., Dover, J.H., Bradley, D.C., Weber, F.R., Bundtzen, T.K., and Haeussler, P.J., 1998, Geologic map of Central (Interior) Alaska: U.S. Geological Survey Open-File Report 98-133, 3 sheets, scale 1:500,000, 63 p. pamphlet, 13 p. appendix. 6960DSw Whirlwind Creek Formation Devonian and late Silurian Shallow-water deposits consisting of several repeated cycles. In the lower part of the formation the cycles grade from algal laminated dolomite into pelletoidal limestone and then into silty limestone and siltstone. In the upper part the cycles grade Patton, W.W., Jr., Wilson, F.H., Labay, K.A., and Shew, Nora, in prep., Reconnaissance geologic map and digital data for the Yukon-Koyukuk basin, Alaska - (Integrated digital geologic map databases of the United States): U.S. Geological Survey Scientifi 6966DSt Tolovana Limestone Middle Devonian to Early Silurian Lower part of alternating green and maroon lime mudstone, succeeded by yellowish-brown weathering, silty to shaly lime mudstone and wackestone, and a main, upper part of light-weathering peloid- and ooid-rich lime packstone and grainstone and rare dolostWilson, F.H., Dover, J.H., Bradley, D.C., Weber, F.R., Bundtzen, T.K., and Haeussler, P.J., 1998, Geologic map of Central (Interior) Alaska: U.S. Geological Survey Open-File Report 98-133, 3 sheets, scale 1:500,000, 63 p. pamphlet, 13 p. appendix. 7261Df Felsic schist Devonian Schistose felsic volcanic rocks, including flows, tuffs, and porphyritic hypabyssal? rocks, interlayered with metasedimentary rocks belonging to units |