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Geologic map of the Fish Creek Reservoir 7.5' quadrangle, Blaine County, Idaho

May 25, 2012

The Fish Creek Reservoir quadrangle in south-central Idaho lies on the north-central margin of the Cenozoic Snake River Plain at the southern end of the Pioneer Mountains. Rocks exposed in the quadrangle range in age from Paleozoic through Cenozoic. Mesozoic rocks are absent. Though Triassic and Jurassic sedimentary rocks may have been deposited in this area, they have been removed by erosion following uplift and thrusting of the Late Cretaceous to early Tertiary Sevier orogeny. The Late Devonian to Early Mississippian Antler orogeny preceded the Sevier. Ordovician through Devonian rocks of western-derived shale and sandstone facies and eastern carbonate shelf facies are unconformably overlain respectively by Pennsylvanian-Permian Wood River and Mississippian Copper Basin Formations. These two sequences are exposed in structural windows juxtaposed by the Sevier-age Pioneer thrust fault. Interpretive cross-sections accompany the map. Volcanic rocks of the Eocene Challis Volcanic Group, Miocene Idavada Volcanics, and Pleistocene Snake River Group cover parts of the area that remains tectonically active.

Citation Information

Publication Year 2012
Title Geologic map of the Fish Creek Reservoir 7.5' quadrangle, Blaine County, Idaho
DOI 10.3133/sim3191
Authors Betty Skipp, Theodore R. Brandt
Publication Type Report
Publication Subtype USGS Numbered Series
Series Title Scientific Investigations Map
Series Number 3191
Index ID sim3191
Record Source USGS Publications Warehouse
USGS Organization Central Mineral and Environmental Resources Science Center