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Geologic Map of the Upper Arkansas River Valley Region, North-Central Colorado

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Geologic Map of the Upper Arkansas River Valley Region, North-Central Colorado Geologic Map of the Upper Arkansas River Valley Region, North-Central Colorado Pamphlet to accompany Scientific Investigations Map 3382 U.S. Department of the Interior U.S. Geological Survey Cover front. View toward the southwest from the valley of the Arkansas River to Mount Elbert (middle skyline), the highest peak in the Sawatch Range as well as the highest in the State of Colorado. Sagebrush-covered terraces barely visible at the bottom of the photograph are underlain by outwash gravel of the Bull Lake glaciation. The tree-covered area, near the western margin of photograph, includes moraines composed of tills of the Pinedale, Bull Lake, and pre-Bull Lake age. Photograph by Ralph R. Shroba, September 18, 2011. Cover back. Bighorn sheep on a large outcrop of Langhoff Gulch Granite, about 5 km north of the town of Granite, Colo. Photograph by K.S. Kellogg, July 2013. Geologic Map of the Upper Arkansas River Valley Region, North-Central Colorado By Karl S. Kellogg, Ralph R. Shroba, Chester A. Ruleman, Robert G. Bohannon, William C. McIntosh, Wayne R. Premo, Michael A. Cosca, Richard J. Moscati, and Theodore R. Brandt Pamphlet to accompany Scientific Investigations Map 3382 U.S. Department of the Interior U.S. Geological Survey U.S. Department of the Interior RYAN K. ZINKE, Secretary U.S. Geological Survey William H. Werkheiser, Acting Director U.S. Geological Survey, Reston, Virginia: 2017 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 https://www.usgs.gov or call 1–888–ASK–USGS. For an overview of USGS information products, including maps, imagery, and publications, visit https://store.usgs.gov. Any use of trade, firm, or product names is for descriptive purposes only and does not imply endorsement by the U.S. Government. Although this information product, for the most part, is in the public domain, it also may contain copyrighted materials as noted in the text. Permission to reproduce copyrighted items must be secured from the copyright owner. Suggested citation: Kellogg, K.S., Shroba, R.R., Ruleman, C.A., Bohannon, R.G., McIntosh, W.C., Premo, W.R., Cosca, M.A., Moscati, R.J.,and Brandt, T.R., 2017, Geologic map of the upper Arkansas River valley region, north-central Colorado: U.S. Geological Survey Scientific Investigations Map 3382, pamphlet 70 p., 2 sheets, scale 1:50,000, https://doi.org/10.3133/sim3382. ScienceBase GIS data release files available at https://doi.org/10.5066/F75B00XQ ISSN 2329-132X (online) iii Contents Abstract ...........................................................................................................................................................1 Introduction.....................................................................................................................................................1 Geologic History .............................................................................................................................................2 Proterozoic History ...............................................................................................................................2 The Gunnison-Salida Volcano-Plutonic Belt ...........................................................................2 Paleoproterozoic Sedimentation, Volcanism, and Intrusive Activity ..................................6 Mesoproterozoic Plutonism .......................................................................................................6 Paleozoic and Early Cretaceous Sedimentary History ...................................................................7 The Laramide Orogeny .........................................................................................................................8 Late Cretaceous to Early Miocene Igneous Activity ......................................................................8 Magmatism Associated with Early Formation of the Northern Rio Grande Rift and the Upper Arkansas River Valley ...............................................................................11 Tectonism and Deposition Associated with Rio Grande Rifting.........................................11 Quaternary History..............................................................................................................................12 Glaciation and Glacial Deposits ..............................................................................................12 Catastrophic Outwash Floods and Their Deposits ...............................................................13 Landslide Deposits and Sackung Features ...........................................................................14 Neotectonics and Seismic Hazards .........................................................................................................14 Hydrologic and Mass-Movement Hazards ..............................................................................................15 Mineral Deposits ..........................................................................................................................................16 Leadville Mining District ....................................................................................................................16 Western Alma Mining District ..........................................................................................................16 Two Bits and Granite Mining Districts .............................................................................................16 Placer Gold Mining Areas Near Granite and Balltown ................................................................17 Weston Pass Mining District ............................................................................................................17 Twin Lakes Mining District ................................................................................................................17 Sugar Loaf and St. Kevin Mining Districts ......................................................................................17 Mount Antero Mining District ...........................................................................................................17 Garfield Mining District ......................................................................................................................17 Sedalia Copper-Zinc Mining District ...............................................................................................18 Browns Canyon Fluorspar Mining District .....................................................................................18 Sand and Gravel Resources .............................................................................................................18 Description of Map Units ............................................................................................................................19 Surficial Deposits ................................................................................................................................19 Anthropogenic Deposits ...........................................................................................................19 Alluvial Deposits.........................................................................................................................19 Glacial Deposits .........................................................................................................................24 Alluvial and Mass-Movement Deposits .................................................................................27 Mass-Movement Deposits .......................................................................................................27 Eolian and Alluvial Deposits .....................................................................................................28 Mass-Movement and (or) Glacial Deposits ..........................................................................29 Wetland Deposits .......................................................................................................................29 Basin-Fill Deposits ..............................................................................................................................29 iv Oligocene and Eocene Volcanic and Mixed Volcanic, Volcaniclastic, and Sedimentary Rocks ............................................................................31 Volcanic Rocks Associated with Early Rio Grande Rifting .................................................31 Pre-Rift Volcanic, Volcaniclastic, and Sedimentary Rocks ................................................34 Upper Eocene Volcanic Rocks of Buffalo Peaks Center .....................................................38 Tertiary and Late Cretaceous Intrusive Rocks ...............................................................................40 Rocks Associated with Early Rio Grande Rifting ..................................................................40 Leucogranite Suite of Mount Antero .............................................................................40 Pre-Rift Intrusive Rocks ............................................................................................................41 Rocks of the Mount Aetna Caldera (Early Oligocene or Late Eocene) ....................42 Rocks of the Mount Princeton Batholith .......................................................................43 Eocene and Paleocene Intrusive Intermediate and Felsic Rocks ............................44
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