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 flank of the quadrangle,
indicative of the multiple tectonic episodes the region has
experienced. Within the western half of the quadrangle, Meso-
and Paleoproterozoic igneous and 	metamorphic rocks of 1.4 Ga
St. Kevin Granite and 1.7-1.8 Ga Biotite gneiss and schist,
respectively, are uplifted along the generally east-dipping,
high-angle Sawatch fault system. In the northwest portion of the
quadrangle, strands of the Homestake shear zone have been mapped,
dated and assigned to the 1.4 Ga Picuris orogeny of northern New
Mexico. 10Be and 26Al cosmogenic nuclide ages of the youngest
glacial deposits indicate a last glacial maximum age of about
21â22 kilo-annum and complete deglaciation by about 14 kilo-annum,
supported by chronologic studies in adjacent drainages. The
Turquoise Lake impounding lateral and terminal moraine complex
was deposited during late Pleistocene glacial maximum ~22-21 ka.
No late Pleistocene tectonic activity is apparent within the
quadrangle.

Tags: 10be-26al, 10th-mountain-division-hut, bald-eagle-mountain, bear-lake, brady-lake, bull-lake-age, bull-lake-glaciation, busk-creek, camp-hale, carlton-tunnel, colorado, colorado-river, cosmogenic-nuclide, cretaceous, eagle-county, eagle-river, eocene, galena-lake, galena-mountain, hagerman-pass, hagerman-tunnel, holocene, homestake-creek, homestake-peak, homestake-reservoir, homestake-shear-zone, isolation-lake, lake-county, lake-esther, landslides, laramide, leadville, leadville-mining-district, leadville-quadrangle, lincoln-porphyry, longs-gulch, mesoproterozoic, metalamprophyre, mill-creek, miocene, miocene-volcanics, mount-massive-wilderness, mount-of-the-holy-cross-wilderness, neotectonics, oligocene, oligocene-volcanics, paleocene, paleoproterozoic, paradise-lakes, pinedale-age, pinedale-glaciation, pitkin-county, pleistocene, pliocene, pliocene-volcanics, porcupine-gulch, pre-bull-lake-age, pre-bull-lake-glaciation, proterozoic, pseudotachylite, quaternary, rio-grande-rift, sakungen, san-isabel-national-forest, sawatch-anticlinorium, sawatch-range, slide-lake, sopris-creek, south-park, st-kevin-granite, st-kevin-mining-district, tennessee-creek, tennessee-park, tennessee-pass, tertiary, timberline-lake, turquoise-lake, uncle-budas-cabin, united-states, upper-arkansas-river, upper-arkansas-valley, usa, usgs-5e1c94a8e4b0ecf25c5efd0f, white-river-national-forest
Organization: Department of the Interior