Entry_ID: (required) Entry_Title: Geologic map of the Frisco quadrangle, Summit County, Colorado Group: Data_Set_Citation Originator(s): Kellogg, Karl S.; Bartos, Paul, J.; Williams, Cindy L. Title: Geologic map of the Frisco quadrangle, Summit County, Colorado Publication: U.S. Geological Survey Miscellaneous Field Studies Map Publication_Date: 2002 Publication_Place: Denver, Colorado Publisher: U.S. Geological Survey URL: http://pubs.usgs.gov/mf/2002/mf-2340/ End_Group Keyword: geology Keyword: geologic maps Keyword: bedrock geologic units Keyword: surficial geologic units Keyword: geologic structure Keyword: geospatial datasets Keyword: earthquake occurrences Keyword: Maroon Keyword: Chinle Keyword: Entrada Keyword: Morrison Keyword: Dakota Keyword: Benton Keyword: Niobrara Keyword: Pierre Group: Temporal_Coverage Start_date: 2000 Stop_date: 2000 End_Group Data_Set_Progress: Complete Group: Spatial_Coverage Southernmost_Latitude: 39.50 Northernmost_Latitude: 39.612 Westernmost_Longitude: -106.125 Easternmost_Longitude: -106.0 End_Group Location: USA Location: Colorado Location: Summit County Group: Data_Resolution Latitude_Resolution: 20 Longitude_Resolution: 20 End_Group Access_Constraints: none Use_Constraints: none. Acknowledgment of the U.S. Geological Survey would be appreciated in products derived from these data. Originating_Center: (required) Group: Data_Center Data_Center_Name: U.S. Geological Survey Information Services Group: Data_Center_Contact Last_name: U.S. Geological Survey Information Services First_name: N/A Phone: 1-888-ASK-USGS Group: Address Box 25286 Denver Federal Center Denver, CO 80225 United States End_Group End_Group End_Group Group: Distribution Distribution_Media: online Distribution_Format : ARCE Fees: none End_Group Group: Distribution Distribution_Media: online Distribution_Format : Shapefile Fees: none End_Group Group: Multimedia_Sample URL: http://pubs.usgs.gov/mf/2002/mf-2340/mf-2340.gif Format: GIF Caption: Reduced-size image of the entire map sheet; 288x277 pixels, 42k bytes. End_Group Group: Multimedia_Sample URL: http://pubs.usgs.gov/mf/2002/mf-2340/mf-2340.pdf Format: PDF Group: Description Printable representation of map layout; includes correlation, cross sections, list of map units, and index maps, 3.6 megabytes. End_Group End_Group Group: Reference End_Group Group: Summary To update and reinterpret earlier geologic mapping, and to achieve a uniform regional geologic database. New 1:24,000-scale geologic mapping along the Interstate-70 urban corridor in western Colorado, in support of the USGS Central Region State/USGS Cooperative Geologic Mapping Project, is contributing to a more complete understanding of the stratigraphy, structure, tectonic evolution, and hazard potential of this rapidly developing region. The 1:24,000-scale Frisco quadrangle is near the headwaters of the Blue River and straddles features of the Blue River graben (Kellogg, K.S., 1999, Neogene basins of the northern Rio Grande rift—partitioning and asymmetry inherited from Laramide and older uplifts: Tectonophysics, v. 305, p. 141-152.), part of the northernmost reaches of the Rio Grande rift, a major late Oligocene to recent zone of extension that extends from Colorado to Mexico. The Williams Range thrust fault, the western structural margin of the Colorado Front Range, cuts the northeastern corner of the quadrangle. The oldest rocks in the quadrangle underlie the Tenmile Range and include biotite-sillimanite schist and gneiss, amphibolite, and migmatite that are intruded by granite inferred to be part of the 1,667-1,750 Ma Routt Plutonic Suite (Tweto, Ogden, 1987, Rock units of the Precambrian- basement in Colorado: U.S. Geological Survey Professional Paper 1321-A, 54 p.). The oldest sedimentary unit is the Pennsylvanian Maroon Formation, a sequence of red sandstone, conglomerate, and interbedded shale. The thickest sequence of sedimentary rocks is Cretaceous in age and includes at least 500 m of the Upper Cretaceous Pierre Shale. The sedimentary rocks are intruded by sills and dikes of dacite porphyry sills of Swan Mountain, dated at 44 Ma (Marvin, R.F., Mehnert, H.H., Naeser, C.W., and Zartman, R.E., 1989, U.S. Geological Survey radiometric ages, compilation “C”—Part five—Colorado, Montana, Utah, and Wyoming: Isochron/West, no. 53, p. 14-19. Simmons, E.C., and Hedge, C.E., 1978, Minor-element and Sr-isotope geochemistry of Tertiary stocks, Colorado mineral belt: Contributions to Mineralogy and Petrology, v. 67, p. 379-396.). Surficial deposits include (1) an old, deeply dissected landslide deposit, possibly as old as Tertiary, on the south flank of Tenderfoot Mountain, (2) deeply weathered, very coarse gravel deposits, mostly along Gold Run and underlying Mesa Cortina; the gravels are gold bearing and were mined by hydraulic methods in the 1800's, (3) glacial deposits of both Bull Lake (middle Pleistocene) and Pinedale (late Pleistocene) that were derived from large valley glaciers that flowed down Tenmile and North Tenmile Creeks; the town of Frisco is underlain mostly by Pinedale-age glacial outwash, (4) recent landslide deposits, including one large (about 1 square kilometer) area just downslope from Lilly Pad Lake, west of I-70, and (5)extensive colluvial and alluvial deposits. The latest seismic events appear to be middle Pliestocene in age and are associated with small scarps that cut Bull Lake till but do not cut Pinedale till. Compilation scale: 1:24,000 Geology mapped in 1997 and 1998. End_Group Group: DIF_Author Last_name: Schweitzer First_name: Peter Middle_name: N Email: pschweitzer@usgs.gov Phone: 703-648-6533 Group: Address Mail Stop 954 12201 Sunrise Valley Dr Reston, VA 20192-0002 USA End_Group End_Group DIF_Revision_Date: 20150202 Science_Review_Date: