Prepared in cooperation with the National Park Service Geologic Map of the Great Smoky Mountains National Park Region, Tennessee and North Carolina By Scott Southworth, Art Schultz, John N. Aleinikoff, and Arthur J. Merschat Pamphlet to accompany Scientific Investigations Map 2997 Supersedes USGS Open-File Reports 03–381, 2004–1410, and 2005–1225 2012 U.S. Department of the Interior U.S. Geological Survey U.S. Department of the Interior KEN SALAZAR, Secretary U.S. Geological Survey Marcia K. McNutt, Director U.S. Geological Survey, Reston, Virginia: 2012 For more information on the USGS—the Federal source for science about the Earth, its natural and living resources, natural hazards, and the environment, visit http://www.usgs.gov or call 1–888–ASK–USGS. 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ISBN 978-1-4113-2403-9 Cover: Looking northeast toward Mount Le Conte, Tenn., from Clingmans Dome, Tenn.-N.C. iii Contents Introduction ....................................................................................................................................................1 Previous Investigations.................................................................................................................................1 Methodology ...................................................................................................................................................3 Field Mapping .......................................................................................................................................3 Digitization and Base Map ..................................................................................................................3 General Geologic Setting and Physiography ...........................................................................................3 Introduction............................................................................................................................................3 Central Blue Ridge Province ..............................................................................................................3 Highlands of the Western Blue Ridge Province ..............................................................................3 Foothills of the Western Blue Ridge Province .................................................................................4 Northern Foothills ........................................................................................................................4 Central Foothills............................................................................................................................5 Southern Foothills ........................................................................................................................5 Tennessee Valley of the Valley and Ridge Province .......................................................................5 Rocks of the Central Blue Ridge Province .................................................................................................5 Rocks of the Highlands of the Western Blue Ridge Province ................................................................5 Mesoproterozoic Basement Complex ...............................................................................................5 Paragneisses ................................................................................................................................7 Ultramafic Rocks .................................................................................................................8 Amphibolite ..........................................................................................................................9 Hornblende-Biotite Gneiss ..............................................................................................10 Orthogneisses.............................................................................................................................10 Migmatitic Biotite Gneiss ...............................................................................................10 Spring Creek Metagranitoid ...........................................................................................10 Metamonzogranite ..........................................................................................................11 Mylonitic Monzogranite ..................................................................................................11 Megacrystic Metagranite ..............................................................................................11 Metagranodiorite .............................................................................................................11 Biotitic Porphyritic Metagranitoid ................................................................................11 Neoproterozoic Ocoee Supergroup ................................................................................................12 Introduction.................................................................................................................................12 Snowbird Group .........................................................................................................................12 Introduction .......................................................................................................................12 Wading Branch Formation ..............................................................................................12 Longarm Quartzite ............................................................................................................12 Roaring Fork Sandstone ..................................................................................................12 Pigeon Siltstone ................................................................................................................13 Metcalf Phyllite .................................................................................................................13 Rich Butt Sandstone .........................................................................................................13 Great Smoky Group ...................................................................................................................14 Introduction .......................................................................................................................14 Elkmont Sandstone ...........................................................................................................14 iv Thunderhead Sandstone .................................................................................................14 Cades Sandstone ..............................................................................................................15 Anakeesta Formation .......................................................................................................15 Copperhill Formation .......................................................................................................16 Wehutty Formation ..........................................................................................................17 Grassy Branch Formation ................................................................................................17 Ammons Formation ...........................................................................................................17 Dean Formation .................................................................................................................17 Rocks of the Murphy Belt .........................................................................................................17 Tusquitee Quartzite and Nantahala Formation ............................................................17 Intrusive Rocks ....................................................................................................................................18 Metadiorite, Metadiabase, and Altered Rocks .....................................................................18 Pegmatite ....................................................................................................................................18 Trondhjemite ...............................................................................................................................19 Vein Quartz .................................................................................................................................19 Rocks of the Foothills of the Western Blue Ridge Province .................................................................19 Neoproterozoic Walden Creek Group .............................................................................................19