Geologic Maps of the Eastern Alaska Range, Alaska, (44 Quadrangles, 1:63360 Scale)
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Report of Investigations 2015-6 GEOLOGIC MAPS OF THE EASTERN ALASKA RANGE, ALASKA, (44 quadrangles, 1:63,360 scale) descriptions and interpretations of map units by Warren J. Nokleberg, John N. Aleinikoff, Gerard C. Bond, Oscar J. Ferrians, Jr., Paige L. Herzon, Ian M. Lange, Ronny T. Miyaoka, Donald H. Richter, Carl E. Schwab, Steven R. Silva, Thomas E. Smith, and Richard E. Zehner Southeastern Tanana Basin Southern Yukon–Tanana Upland and Terrane Delta River Granite Jarvis Mountain Aurora Peak Creek Terrane Hines Creek Fault Black Rapids Glacier Jarvis Creek Glacier Subterrane - Southern Yukon–Tanana Terrane Windy Terrane Denali Denali Fault Fault East Susitna Canwell Batholith Glacier Maclaren Glacier McCallum Creek- Metamorhic Belt Meteor Peak Slate Creek Thrust Broxson Gulch Fault Thrust Rainbow Mountain Slana River Subterrane, Wrangellia Terrane Phelan Delta Creek River Highway Slana River Subterrane, Wrangellia Terrane Published by STATE OF ALASKA DEPARTMENT OF NATURAL RESOURCES DIVISION OF GEOLOGICAL & GEOPHYSICAL SURVEYS 2015 GEOLOGIC MAPS OF THE EASTERN ALASKA RANGE, ALASKA, (44 quadrangles, 1:63,360 scale) descriptions and interpretations of map units Warren J. Nokleberg, John N. Aleinikoff, Gerard C. Bond, Oscar J. Ferrians, Jr., Paige L. Herzon, Ian M. Lange, Ronny T. Miyaoka, Donald H. Richter, Carl E. Schwab, Steven R. Silva, Thomas E. Smith, and Richard E. Zehner COVER: View toward the north across the eastern Alaska Range and into the southern Yukon–Tanana Upland highlighting geologic, structural, and geomorphic features. View is across the central Mount Hayes Quadrangle and is centered on the Delta River, Richardson Highway, and Trans-Alaska Pipeline System (TAPS). Major geologic features, from south to north, are: (1) the Slana River Subterrane, Wrangellia Terrane; (2) the Maclaren Terrane containing the Maclaren Glacier Metamorphic Belt to the south and the East Susitna Batholith to the north; (3) the Windy Terrane; (4) the Aurora Peak Terrane; and (5) the Jarvis Creek Glacier Subterrane of the Yukon–Tanana Terrane. Major structural features, from south to north, are: (1) the young (late Pleistocene) McCallum–Slate Creek Thrust along which Tertiary sedimentary rocks are being thrust under the Wrangellia Terrane; (2) the Late Cretaceous Broxson Gulch Thrust along which the Wrangellia Terrane is thrust under the Maclaren Terrane; (3) the Late Cretaceous Meteor Peak Fault along which the Maclaren Glacier Metamorphic Belt is thrust under the East Susitna Batholith; (4) the active Denali Fault that separates the Maclaren and Wrangellia Terranes to the south from the Windy, Aurora Peak, and Yukon–Tanana Terranes to the north; and (5) the late Pleistocene Hines Creek Fault that separates the Aurora Peak Terrane to the south from the Yukon–Tanana Terrane to the north and along which the Yukon–Tanana Terrane is being thrust over Pleistocene glacial moraines. Major geomorphic features, from south to north, are: (1) the east–west-trending Eastern Alaska Range; (2) Rainbow Mountain along the southern margin of the Alaska Range; (3) Canwell and Black Rapids Glaciers that occur mainly along the Denali Fault, which cuts through the center of the Eastern Alaska Range; (4) the southeastern part of the Tanana Basin; and (5) the Southern Yukon–Tanana Upland; and (5) the Delta River that flows northward across the Alaska Range. Report of Investigations 2015-6 State of Alaska Department of Natural Resources Division of Geological & Geophysical Surveys STATE OF ALASKA Bill Walker, Governor DEPARTMENT of NATURAL RESOURCES Mark Myers, Ph.D., Commissioner diVision of GEOLOGICAL & GEOPHYsical surVeYs Steve Masterman, State Geologist and Director Publications produced by the Division of Geological & Geophysical Surveys (DGGS) are available for free download from the DGGS website (www.dggs.alaska.gov). Publications on hard-copy or digital media can be examined or purchased in the Fairbanks office: alaska division of geological & geophysical surveys 3354 college rd., fairbanks, alaska 99709-3707 phone: (907) 451-5020 fax (907) 451-5050 dggspubs@alaska.gov www.dggs.alaska.gov Alaska State Library Alaska Resource Library & Information State Office Building, 8th Floor Services (ARLIS) 333 Willoughby Avenue 3150 C Street, Suite 100 Juneau, Alaska 99811-0571 Anchorage, Alaska 99503-3982 Elmer E. Rasmuson Library University of Alaska Anchorage Library University of Alaska Fairbanks 3211 Providence Drive Fairbanks, Alaska 99775-1005 Anchorage, Alaska 99508-4614 CONTENTS INTRODUCTION .......................................................................................................................... 1 General information and topographic setting of the eastern Alaska Range ......................................................................... 1 Geologic setting of the eastern Alaska Range ...................................................................................................................... 1 Terranes north of the Denali fault ................................................................................................................................. 1 Terranes along the Denali fault ..................................................................................................................................... 1 Terranes south of the Denali fault ................................................................................................................................. 3 Late Mesozoic to middle Tertiary granitic plutonic belts ............................................................................................... 3 Tertiary sedimentary and volcanic rocks ....................................................................................................................... 3 Quaternary surficial deposits, glaciers, and ice fields ................................................................................................... 3 Major faults ................................................................................................................................................................... 4 Tectonic summary ......................................................................................................................................................... 4 Description of geologic mapping .......................................................................................................................................... 4 Prior geologic mapping......................................................................................................................................................... 5 Data quality .......................................................................................................................................................................... 5 Acknowledgments ................................................................................................................................................................ 5 summarY of map UNITS ......................................................................................................... 6 DESCRIPTION of map UNITS ................................................................................................... 11 Surficial units ...................................................................................................................................................................... 11 Glacial deposits .................................................................................................................................................................. 11 Tertiary sedimentary and volcanic rocks — north of Denali Fault ...................................................................................... 12 Post-accretionary alkalic mafic and associated plutonic rocks — north of Denali Fault .................................................... 13 Post-accretionary granitic plutonic rocks — north of Denali Fault .................................................................................... 14 Post-accretionary mafic plutonic rocks — north of Denali Fault ........................................................................................ 16 Terranes — north of Denali Fault (from north to south) .................................................................................................... 17 Yukon–Tanana terrane................................................................................................................................................. 17 Macomb subterrane — South of Tanana River fault and north of Elting Creek fault ........................................... 18 Jarvis Creek Glacier subterrane — South of Elting Creek fault and north of Hines Creek and Mount Gakona faults ...................................................................................................................................................... 19 Pingston terrane — South of Hines Creek fault and north of Nenana Glacier and Denali faults ................................ 23 Aurora Peak terrane — South of Nenana Glacier fault and north of Denali fault ....................................................... 25 Windy terrane — In splays of Denali fault ................................................................................................................... 27 Tertiary sedmentary rocks — south of Denali Fault ........................................................................................................... 28 Tertiary volcanic and intrusive