bedrock geologic map of the northern alaska peninsula area ... · list of map units [see...
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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°
60°57'30"
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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