Data release for Geologic Map of the Leadville North 7.5' quadrangle, Eagle and Lake Counties, Colorado

The Leadville North 7.5' quadrangle lies at the northern end of the Upper Arkansas Valley, where the Continental Divide at Tennessee Pass creates a low drainage divide between the Colorado and Arkansas River watersheds. In the eastern half of the quadrangle, the Paleozoic sedimentary section dips generally 20–30 degrees east. At Tennessee Pass and Missouri Hill, the core of the Sawatch anticlinorium is mapped as displaying a tight hanging-wall syncline and foot-wall anticline within the basement-cored structure. High-angle, west-dipping, Neogene normal faults cut the eastern margin of the broad, Sawatch anticlinorium. Minor displacements along high-angle, east- and west-dipping Laramide reverse faults occurred in...

Tags: 10Be, 26Al, Belden Formation, Buckeye Peak, Bull Lake glaciation, Camp Hale, All tags... Chaffee Group, Chicago Ridge, Colorado, Colorado River, Cooper Hill, Dotsero Formation, Eagle County, Eagle River, East Fork Arkansas River, Geomorphology, Gray porphyry group, Hornblende Latite Porphyry, Lake County, Laramide, Leadville, Leadville Limestone, Leadville Quadrangle, Lincoln Porphyry, Manitou Dolomite, Minturn Formation, Missouri Hill, Mosquito Range, Mount Zion, No Name Gulch, Pinedale Glaciation, Rio Grande rift, Sawatch Quartzite, Sawatch Range, Sawatch anticlinorium, South Park, St. Kevin Granite, Structural Geology, Tennessee Creek, Tennessee Park, Tennessee Pass, Turquoise Lake, USA, USGS Science Data Catalog (SDC), United States, Upper Arkansas River, Upper Arkansas Valley, White Porphyry Group, cosmogenic nuclide, neotectonics, pre-Bull Lake glaciation, Fewer tags

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...

Categories: Data; Types: Downloadable, GeoTIFF, Map Service, Raster; Tags: 10Be, 26Al, 10th Mountain Division Hut, Bald Eagle Mountain, Bear Lake, Brady Lake, All tags... Bull Lake glaciation, Busk Creek, Camp Hale, Carlton Tunnel, Colorado, Colorado River, Eagle County, Eagle River, Economic Geology, Galena Lake, Galena Mountain, Geomorphology, Glaciology, Hagerman Pass, Hagerman Tunnel, Homestake Creek, Homestake Peak, Homestake Reservoir, Homestake shear zone, Hydrology, Isolation Lake, Lake County, Lake Esther, Laramide, Leadville, Leadville Mining District, Leadville Quadrangle, Lincoln Porphyry, Longs Gulch, Mill Creek, Mineral Resources, Miocene volcanics, Mount Massive Wilderness, Mount of the Holy Cross Wilderness, Oligocene volcanics, Paradise Lakes, Pinedale Glaciation, Pitkin County, Pliocene volcanics, Porcupine Gulch, Rio Grande rift, San Isabel National Forest, Sawatch Range, Sawatch anticlinorium, Slide Lake, Soil Sciences, Sopris Creek, South Park, St. Kevin Granite, St. Kevin Mining District, Structural Geology, Tennessee Creek, Tennessee Park, Tennessee Pass, Timberline Lake, Turquoise Lake, USA, USGS Science Data Catalog (SDC), Uncle Bud’s Cabin, United States, Upper Arkansas River, Upper Arkansas Valley, Water Resources, White River National Forest, cosmogenic nuclide, landslides, metalamprophyre, neotectonics, pre-Bull Lake glaciation, pseudotachylite, sakungen, Fewer tags

Synoptic reconstruction of a major ancient lake system: Eocene Green River Formation, western United States

Numerous 40Ar/39Ar experiments on sanidine and biotite from 22 ash beds and 3 volcaniclastic sand beds from the Greater Green River, Piceance Creek, and Uinta Basins of Wyoming, Colorado, and Utah constrain ~8 m.y. of the Eocene Epoch. Multiple analyses were conducted per sample using laser fusion and incremental heating techniques to differentiate inheritance, 40Ar loss, and 39Ar recoil. When considered in conjunction with existing radioisotopic ages and lithostratigraphy, biostratigraphy, and magnetostratigraphy, these new age determinations facilitate temporal correlation of linked Eocene lake basins in the Laramide Rocky Mountain region at a significantly increased level of precision. To compare our results...

Categories: Publication; Types: Citation, Journal Citation; Tags: Ar-Ar, Geological Society of America Bulletin, Green River Formation, Piceance Creek Basin, Uinta Basin, All tags... absaroka, eocene, lake type, land-mammal ages, laramide, Fewer tags