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LIST OF MAP UNITS

[See Description of Map Units (in pamphlet) for complete unit descriptions. Some exposures on the plotted map are too small to distinguish the color for identification. These units are labeled where possible, and unlabeled units are attributed in the database]

UNCONSOLIDATED DEPOSITS AND ROCKS NOT ASSIGNED TO A PROVINCESurficial deposits, undivided (Quaternary)

Bedrock unknown (age unknown)—Not shown in Correltation of Map Units

Kuskokwim Group, undivided (Cretaceous, Campanian(?) to Albian(?))

Nearshore facies (Cretaceous)

Volcanogenic rocks (Cretaceous(?))

AHKLUN MOUNTAINS PROVINCE

SEDIMENTARY ROCKSVolcanic and sedimentary rocks (Lower Cretaceous to Middle Jurassic)

Olivine basalt and fragmental volcanic rocks (Cretaceous or Jurassic)

Graywacke of Kulukak Bay (Upper to Middle Jurassic)

STRUCTURAL ASSEMBLAGETogiak-Tikchik Complex (Lower Cretaceous to Lower Paleozoic)

Melange (Mesozoic(?))

Argillite and graywacke, cut by dike swarms (Lower Cretaceous to Upper Triassic)

Argillite and graywacke (Lower Cretaceous to Upper Triassic)

Sedimentary rocks (Lower Jurassic)

Phyllite and chert (Lower Jurassic and Upper Triassic(?))

Chert and limestone (Upper Triassic)

Volcanic rocks (Upper Triassic)

Rainbow chert (Triassic(?) to Paleozoic(?))

Volcanic rocks (Permian(?))

Limestone (Permian)

Clastic rocks (Permian(?))

Greenstone and schist (Mississippian(?) and (or) Devonian(?))

Black chert (lower Paleozoic(?))

LIME HILLS PROVINCE

SEDIMENTARY ROCKSChert, sandstone, and siltstone (Lower Jurassic)

Limestone, silty limestone, and chert (Upper Triassic, Norian)

Farewell terrane, Nixon Fork subterrane of Decker and others (1994), undi-vided (Devonian(?) to Proterozoic)

Algal boundstone (Upper Silurian, Pridoli and Ludlow)

Lime mudstone (Upper Silurian, Wenlock to late Llandovery)

Tcherskidium-bearing limestone (Upper Ordovician, Ashgillian)

Shale (Ordovician)

Algal boundstone and lime mudstone (Lower Ordovician)

Lime mudstone (Lower Ordovician)

Limestone (Middle Cambrian)

Clastic and carbonate rocks (Lower Cambrian)

Dolostone, limestone, orthoquartzite, and minor chert (Neoproterozoic(?))

ALASKA-ALEUTIAN RANGE PROVINCE

SEDIMENTARY ROCKSSedimentary rocks (Tertiary, Pliocene or Miocene)

Kenai Group, Tyonek Formation, and Hemlock Conglomerate, undivided (Tertiary, Miocene and Oligocene)

West Foreland Formation (Tertiary, early Eocene and late Paleocene)

Copper Lake Formation, undivided (Tertiary, Eocene and Paleocene(?))

Saddle Mountain section of Magoon and others (1980) (Upper Cretaceous, Maastrichtian)

Kaguyak Formation (Upper Cretaceous, Maastrichtian and Campanian)

Koksetna River sequence of Wallace and others (1989) (Lower Cretaceous, Valanginian, to Upper Jurassic, Kimmeridgian)

Naknek Formation (Upper Jurassic, Tithonian to Oxfordian)

Pomeroy Arkose Member (Upper Jurassic, Kimmeridgian and Oxfordian(?))

Indecision Creek Sandstone Member (Upper Jurassic, Kimmeridgian and Oxfordian(?))

Snug Harbor Siltstone Member (Upper Jurassic, Kimmeridgian and Oxfordian)

Northeast Creek Sandstone Member (Upper Jurassic, Oxfordian)

Chisik Conglomerate Member (Upper Jurassic, Oxfordian)

Chinitna Formation (Middle Jurassic, Callovian)

Paveloff Siltstone Member

Tonnie Siltstone Member

Tuxedni Group (Middle Jurassic, Callovian to Bajocian)

Bowser Formation (Middle Jurassic, Callovian and Bathonian)

Twist Creek Siltstone (Middle Jurassic, Bajocian)

Cynthia Falls Sandstone (Middle Jurassic, Bajocian(?))

Fitz Creek Siltstone (Middle Jurassic, middle Bajocian)

Gaikema Sandstone (Middle Jurassic, lower middle Bajocian)

Red Glacier Formation (Middle Jurassic, lower middle Bajocian to lower Bajocian)

Talkeetna Formation, undivided (Lower Jurassic)

Horn Mountain Tuff Member

Portage Creek Agglomerate Member

Marsh Creek Breccia Member

Kamishak Formation, undivided (Upper Triassic, Norian)

Ursus Member

Middle Member

Bruin Limestone Member

Gray shale and gray volcaniclastic sandstone (Triassic)

STRUCTURAL ASSEMBLAGEKakhonak and Tlikakila Complexes (Jurassic, Triassic, and Permian(?) or

older(?))

IGNEOUS ROCKSVolcanic rocks, undivided (Quaternary)

Volcanic rocks (Quaternary, Holocene)

Debris-flow deposits (Quaternary, Holocene)

Volcanic rubble and mudflows (Quaternary, Holocene)

Andesite and dacite domes

Volcanic rocks, undivided (Quaternary, Pleistocene, or Tertiary, Pliocene)

Alaska-aleutian Range Batholith of Reed and Lamphere (1969)

Intrusive rocks, undivided (Tertiary)

Granite and aplite (Tertiary, Oligocene(?) and younger)

Peralkaline granite

Gabbronorite

Granodiorite and quartz monzodiorite (Tertiary, Oligocene and late Eocene)

Granite (Tertiary, late Eocene)

Older granite (Tertiary, Paleocene)

Granodiorite (Tertiary, Paleocene)

Mafic granitic rocks (Cretaceous and (or) Jurassic)

Trondhjemite (Late Jurassic)

Lamprophyre and basalt dikes (Jurassic)

Granodiorite and quartz monzonite (Jurassic)

Quartz diorite, tonalite, and diorite (Jurassic)

Mafic and ultramafic plutonic rocks (Early Jurassic)

Cottonwood Bay and Chilikadrotna Greenstones (Triassic)

METAMORPHIC ROCKSMetamorphosed mafic volcanic and sedimentary rocks (Mesozoic and (or)

Paleozoic)

IGNEOUS ROCKS, ALL PROVINCESVolcanic rocks, undivided (Tertiary)

Basaltic volcanic rocks (late Tertiary)

Gibraltar Lake Tuff (Tertiary, Pliocene(?) to Oligocene(?))

Felsic volcanic rocks

Volcanic rocks, undivided (Tertiary, Oligocene and Eocene)

Tuffaceous felsic volcanic rocks

Basalt and andesite

Ignimbrite (Tertiary, Paleocene)

Volcanic rocks (Tertiary and (or) Cretaceous)

Rhyolite and dacite flows, tuff, dikes, and sills

Basalt flows

Granitic rocks, undivided (Tertiary and (or) Cretaceous)

Granite and alaskite

Syenitic rocks

Quartz monzonite and quartz monzodiorite

Granodiorite

Monzodiorite and quartz diorite

Plutonic rocks, undivided (Cretaceous)

Quartz monzonite and syenite (Late Cretaceous)

Granodiorite (Late Cretaceous)

Granite

Granodiorite

Quartz diorite, tonalite, and diorite

Mafic igneous rocks (Mesozoic(?))

EXPLANATION OF MAP SYMBOLSContact—Solid where location is certain; long-dashed where location is approxi-

mate; short-dashed where location is inferred; dotted where location is concealed.

Fault—Solid where location is certain; long-dashed where location is approximate; short-dashed where location is inferred; dotted where location is concealed

Thrust fault—Solid where location is certain; long-dashed where location is approximate; short-dashed where location is inferred; dotted where location is concealed. Sawteeth on upper plate

High-angle thrust fault—Solid where location is certain; long-dashed where location is approximate; short-dashed where location is inferred; dotted where location is concealed. Sawteeth on upper plate

Caldera or crater rim—Solid where location is certain

Moraine—End, recessional, and lateral moraine limit; hachures point toward ice

Terrace, erosional, or wave-cut scarp—Hachures point toward water

Dike

Lineament

Contact metamorphosed rock

Community

QUATERNARY

CRETACEOUS

TRIASSIC

PERMIAN

PENNSILVANIAN

MISSISSIPPIAN

DEVONIAN

SILURIAN

ORDOVICIAN

TERTIARY

JURASSIC

CAMBRIAN

PROTEROZOIC

CORRELATION OF MAP UNITS

[See Description of Map Units (in pamphlet) for precise unit ages]

AHKLUN MOUNTAINS PROVINCE

SEDIMENTARY ROCKS

UNCONSOLIDATED DEPOSITS AND ROCKS NOT ASSIGNED

TO A PROVINCE

STRUCTURAL ASSEMBLAGE

LIME HILLS PROVINCE

SEDIMENTARYROCKS IGNEOUS ROCKS

STRUCTURALASSEMBLAGE

ALASKA ALEUTIAN RANGE PROVINCE IGNEOUS ROCKS, ALL PROVINCES

METAMORPHICROCKSSEDIMENTARY ROCKS

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156°156°7'30"156°15'156°22'30"156°30'156°37'30"156°45'156°52'30"157°157°07'30"61°

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U.S. Department of the InteriorU.S. Geological Survey

Scientific Investigations Map 2942Sheet 2 of 2

Pamphlet accompanies map

Figure 1. Enlarged part of map showing Paleozoic and Proterozoic rock units of the Lime Hills province in the northeastern Taylor Mountains quadrangle.

Bedrock Geologic Map of the Northern Alaska Peninsula Area, Southwestern AlaskaCompiled By

Frederic H. Wilson, Robert B. Blodgett, Charles D. Blome, Solmaz Mohadjer, Cindi C. Preller, Edward P. Klimasauskas, Bruce M. Gamble, and Warren L. Coonrad

2017

Any use of trade, product, or firm names in this publication is for descriptive purposes only and does not imply endorsement by the U.S. Government

This map was printed on an electronic plotter directly from digital files. Dimensional calibration may vary between electronic plotters and between X and Y directions on the same plotter, and paper may change size due to atmospheric conditions; therefore, scale and proportions may not be true on plots of this map.

For sale by U.S. Geological Survey, Information Services, Box 25286, Federal Center, Denver, CO 80225, 1–888–ASK–USGS

Digital files available at https://doi.org/10.3133/sim2942

Suggested citation: Wilson, F.H., Blodgett, R.B., Blome, C.D., Mohadjer, S., Preller, C.C., Klimasauskas, E.P., Gamble, B.M., and Coonrad, W.L., 2017, Bedrock geologic map of the Alaska Peninsula area, southwestern Alaska: U.S. Geological Survey Scientific Investigations Map 2942, pamphlet 43 p., scale 1:350,000, https://doi.org/10.3133/sim2942.

ISSN 2329-132X (online)

https://doi.org/10.3133/sim2942