Preliminary Geologic Map of the Sloan Quadrangle, Clark County, Nevada
Authors: Nicholas H. Hinz, Alan R. Ramelli, and Seth Dee
Series: Open-File Report 15-7
Format: plate: 37 x 26 inches, color, includes 1 cross section; text: 4 pages, b/w
A 1:24,000 scale, preliminary geologic map of the Sloan 7.5-minute quadrangle in Clark County, Nevada. This quadrangle straddles Interstate Highway 15 along the south side of Las Vegas Valley and abuts the drainage divide with Ivanpah Valley. The actively managed Sloan Quarry is located in the NW quarter of the quadrangle. The north half of the quadrangle includes new housing developments in the City of Henderson, the Henderson Executive Airport, and new developments in the unincorporated communities of Paradise, Enterprise, and Sloan. The southeastern margin of this map area covers the north end of Hidden Valley and contains parts of each of the following land use features: the Sloan Canyon National Conservation Area, the Sloan Canyon Rock Art Site, and the Sloan Rock Art Area of Critical Environmental Concern.
The bedrock exposures in the quadrangle consist of Paleozoic carbonate basement and Tertiary volcanic and sedimentary rocks. The Paleozoic stratigraphy includes the Early to Middle Devonian Sultan Limestone, the Late Devonian to Early Mississippian Crystal Pass Limestone, the Mississippian Monte Cristo Group, and the Late Mississippian to Early Permian Bird Spring Formation. Four sub-units in the commonly undivided lower part the Bird Spring Formation were distinguished in the Sloan quadrangle. The Tertiary section includes a complex section of fluvial gravels and volcanic rocks. The fluvial gravels reach 350 m thick, fill a previously unrecognized paleovalley segment with as much as 500 m of preserved paleotopography. The volcanic rocks include middle Miocene basalt, basaltic andesite, andesite, and dacite that were locally erupted. The lower-most volcanic rocks are intercalated with the uppermost fluvial gravels. The Paleozoic section was initially deformed during the Sevier and/or Laramide orogenies and were displaced along reverse faults, thrust faults, and strike-slip faults. Normal faults associated with Basin and Range extension cut the Paleozoic strata and the lower half of the Tertiary section. Faults were not observed cutting the upper half of the Tertiary strata or the Quaternary surficial deposits.
This map was prepared as a part of the STATEMAP component of the National Cooperative Geologic Mapping Program in cooperation with the U.S. Geological Survey.
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