Geologic Map of the eastern half of the Vail 30' x 60' Quadrangle, Eagle, Summit, and Grand Counties, Colorado By Karl S. Kellogg, Ralph R. Shroba, Wayne R. Premo, and Bruce Bryant 2011 Scientific Investigations Map 3170 ABSTRACT Recent mapping and geochronologic studies for the eastern half of the Vail 1:100,000-scale quadrangle have significantly improved our understanding of (1) Paleoproterozoic history of the basement rocks of the Gore Range and Williams Fork Mountains (western margin of the Front Range), (2) the Late Paleozoic history of the Gore fault system, (3) Laramide contractional tectonism, including deformation along the Gore fault and Williams Range thrust, (4) Oligocene and younger extensional history of the Blue River half graben (The northern extent of the Rio Grande rift), and (5) late Neogene and Quaternary surficial history. The recently active Gilman mining district, a major producer of zinc and lead, is in the southwestern corner of the map area. Marine sediments and mafic to felsic volcanic rocks deposited between about 1,740 and 1,780 m.y. were generally metamorphosed to amphibolite grade and intruded and deformed by mostly calc-alkalic granitic rocks during an orogenic episode that lasted about 110 m.y. The distribution of well-studied Upper Cambrian to thick Upper Cretaceous platform sediments is now greatly improved, which allows a better definition of the late Paleozoic uplift, erosion, and flanking sedimentation of the ancestral Front Range. Detailed mapping has also better defined the geometry of Late Cretaceous to early Tertiary Laramide deformation along both the Gore fault system and Williams Range thrust, as well as increased understanding of the details of mostly Neogene extension along the Blue River normal fault system (the western margin of the Blue River half graben). Scarps along the latter fault system indicate movement may be as young as Holocene. Detailed mapping of surficial deposits has defined and described (1) six ages of terrace alluvium, (2) three general ages of landslides, (3) glacial and periglacial deposits, and (4) fan, pediment, talus, and debris-flow deposits. Purpose: The map is intended as a database for a variety of land-use and scientific purposes, including (1) assessment of geologically stable building sites, (2) planning for road and highway construction, (3) assessment of groundwater resources, (4) assessment of mineral resources, (5) determining geologic-hazard potential (flooding, landslide, rockfall, and seismic risk), (6) evaluating the structure of the northern Rio Grande rift in the Blue River valley, (7) improvement in understanding of the sedimentary section, which spans the period from the Cambrian to the Holocene, and (8) new insights into the geologic history of the Proterozoic basement rocks, including a number of new radiometric dates. DISCLAIMERS This database, identified as SIM3170, has been approved for release and publication by the Director of the USGS. Although this database has been subjected to rigorous review and is substantially complete, the USGS reserves the right to revise the data pursuant to further analysis and review.Furthermore, it is released on condition that neither the USGS nor the United States Government may be held liable for any damages resulting from its authorized or unauthorized use. Although these data have been processed successfully on a computer system at the U.S. Geological Survey, no warranty, expressed or implied is made regarding the display or utility of the data on any other system, or for general or scientific purposes, nor shall the act of distribution constitute such warranty. The U.S.Geological Survey shall not be held liable for improper or incorrect use of the data described and/or contained herein. Any use of trade, product or firm names is for descriptive purposes only and does not imply endorsement by the U.S. Geological Survey. Although this information product, for the most part, is in the public domain, it also contains copyrighted material as noted in the text. Permission to reproduce copyrighted items for other than personal use must be secured from the copyright owner. DATA FILES The database can be downloaded via the Web from http://pubs.usgs.gov/sim/3170/. ArcInfo export files, ArcView shapefiles, and an ArcGIS geodatabase may be extracted from a zip-compressed file (SIM3170_GIS.zip). In addition, an Adobe Portable Document Format (PDF) file (SIM3170_map.pdf, or SIM3170_map_hillshade) can be downloaded, from which paper copies may be printed. The database contact is: Karl S. Kellogg (303) 236-1305 kkellogg@usgs.gov U.S. Geological Survey Box 25046, Mail Stop 913 Denver, CO 80225 The data were compiled from both published and unpublished mapping. Jack Reed Marith Reheis (USGS), reviewed the geologic map. This geospatial database, SIM3170_GIS.gdb, consists of ArcInfo export files (.e00), ArcView shapefiles, and ArcGIS geodatabase files.See the list below. Please refer to the file SIM3170.met for detailed metadata documentation for this geospatial database. List of files: 00ReadMe.txt SIM3170_pamphlet.pdf SIM3170_map.pdf SIM3170.met vaileast.tif vaileast.tfw SIM3170_datafiles.zip: SIM3170.gdb directory (contains GIS data as geodatabase feature classes) geology: boundary_clp_poly vaileast_geo_label vaileast_geo_line vaileast_geo_line2 vailest_geo_pnt vaileast_geo_poly vaileast_geo_shearzone vaileast_xsection shapefiles directory: vaileast_clp_poly.shp (.shx/dbf./prj./sbn./sbx./shp.xml/) vaileast_geo_label.shp (.shx/dbf./prj./sbn./sbx./shp.xml/) vaileast_geo_line.shp (.shx/dbf./prj./sbn./sbx./shp.xml/) vaileast_geo_line2.shp (.shx/dbf./prj./sbn./sbx./shp.xml/) vaileast_geo_pnt.shp (.shx/dbf./prj./sbn./sbx./shp.xml/) vaileast_geo_poly.shp (.shx/dbf./prj./sbn./sbx./shp.xml/) vaileast_geo_shearzone.shp (.shx/dbf./prj./sbn./sbx./shp.xml/) vaileast_xsection.shp (.shx/dbf./prj./sbn./sbx./shp.xml/) HOW TO OBTAIN THE DIGITAL FILES The digital files constituting the geologic map database of this report can be obtained via the Internet from the U.S.Geological Survey publications website. Go to the web page at http://pubs.usgs.gov/sim/3170/ and follow the directions to download the files. The main product is a Portable Document Format (.pdf) map, which requires Adobe Acrobat for viewing. Acrobat software runs on a variety of systems, and is available for download free of charge from Adobe at http://www.adobe.com.