Filters: Tags: Miocene volcanics (X)3 results (68ms)
Data release for Geologic Map of the Homestake Reservoir 7.5' quadrangle, Lake, Pitkin, and Eagle Counties, Colorado
The Homestake Reservoir 7.5' quadrangle lies at the northwestern end of the Upper Arkansas Valley, and headwaters of the Arkansas River, and the Roaring Fork, Fryingpan, and Eagle Rivers of the Colorado River system. The quadrangle lies within tectonic provinces of the 1.4 Ga Picuris Orogeny, the late Paleozoic Ancestral Rockies, Late Cretaceous-Paleocene Laramide orogeny, Oligocene to Miocene, and Pliocene?, volcanism, and Miocene to the present Rio Grande rift extensional tectonics. In the eastern half of the quadrangle, high-angle, east-dipping, Neogene normal faults displace Proterozoic rocks, and locally Mio-Pliocene? volcanic rocks. Many quartz veins and hydrothermally altered zones are exposed along the eastern...
Digital geologic map and map database of parts of Marin, SanFrancisco, Alameda, Contra Costa, and Sonoma Counties, California
This digital map database, compiled from previously published andunpublished data, and new mapping by the authors, represents thegeneral distribution of bedrock and surficial deposits in the mapped area.Together with the accompanying text file (mageo.txt, mageo.pdf, ormageo.ps), it provides current information on the geologic structure andstratigraphy of the area covered. The database delineates map units thatare identified by general age and lithology following the stratigraphicnomenclature of the U.S. Geological Survey. The scale of the source mapslimits the spatial resolution (scale) of the database to 1:62,500 orsmaller.
Data release for Surficial Geology of the Northern San Luis Valley, Saguache, Fremont, Custer, Alamosa, Rio Grande, Conejos, and Costilla Counties, Colorado
The San Luis Valley and associated underlying basin of south-central Colorado and north-central New Mexico is the largest structural and hydrologic basin of the Rio Grande Rift and fluvial system. The surrounding San Juan and Sangre de Cristo Mountains reveal evidence of widespread volcanism and transtensional tectonism beginning in the Oligocene and continuing to the present, as seen in fault displacement of Pleistocene to Holocene deposits along the eastern basin-bounding Sangre de Cristo fault system and fault zones along the western margin of the basin. The San Luis basin can generally be subdivided into northern and southern basins at the structural and physiographic high terrain of the San Luis Hills in the...