Geologic map of the Mound Spring quadrangle, Nye and Clark Counties, Nevada, and Inyo County, California
March 1, 2003
The Mound Spring quadrangle, the southwestern-most 7.5' quadrangle of the area of the Las Vegas 1:100,000-scale quadrangle, is entirely within the Pahrump Valley, spanning the Nevada/California State line. New geologic mapping of the predominantly Quaternary materials is combined with new studies of gravity and geochronology in this quadrangle. Eleven predominantly fine-grained units are delineated, including playa sediment, dune sand, and deposits associated with several cycles of past groundwater discharge and distal fan sedimentation. These units are intercalated with 5 predominantly coarse-grained alluvial-fan and wash gravel units mainly derived from the Spring Mountains. The gravel units are distinguished on the basis of soil development and associated surficial characteristics. Thermoluminescence and U-series geochronology constrain most of the units to the Holocene and late and middle Pleistocene. Deposits of late Pleistocene groundwater discharge in the northeast part of the quadrangle are associated with a down-to-the-southwest fault zone that is expressed by surface fault scarps and a steep gravity gradient. The gravity field also defines a northwest-trending uplift along the State line, in which the oldest sediments are poorly exposed. About 2 km to the northeast a prominent southwest-facing erosional escarpment is formed by resistant beds in middle Pleistocene fine-grained sediments that dip northeast away from the uplift. These sediments include cycles of groundwater discharge that were probably caused by upwelling of southwesterly groundwater flow that encountered the horst.
Citation Information
Publication Year | 2003 |
---|---|
Title | Geologic map of the Mound Spring quadrangle, Nye and Clark Counties, Nevada, and Inyo County, California |
DOI | 10.3133/mf2339 |
Authors | Scott C. Lundstrom, Shannon Mahan, Richard J. Blakely, James B. Paces, Owen D. Young, Jeremiah B. Workman, Gary L. Dixon |
Publication Type | Report |
Publication Subtype | USGS Numbered Series |
Series Title | Miscellaneous Field Studies Map |
Series Number | 2339 |
Index ID | mf2339 |
Record Source | USGS Publications Warehouse |
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Scott C Lundstrom, Ph.D.
Scientist Emeritus
Scientist Emeritus
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Shannon Mahan
Research Geologist, TRIGA Reactor System Administrator
Research Geologist, TRIGA Reactor System Administrator
Email
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Richard Blakely
Scientist Emeritus
Scientist Emeritus
Email
Phone
James Paces
Scientist Emeritus
Scientist Emeritus
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Phone
Jeremiah Workman
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Phone
Related
Scott C Lundstrom, Ph.D.
Scientist Emeritus
Scientist Emeritus
Email
Phone
Shannon Mahan
Research Geologist, TRIGA Reactor System Administrator
Research Geologist, TRIGA Reactor System Administrator
Email
Phone
Richard Blakely
Scientist Emeritus
Scientist Emeritus
Email
Phone
James Paces
Scientist Emeritus
Scientist Emeritus
Email
Phone
Jeremiah Workman
Email
Phone