Title: Geologic map of the South Bastian Spring quadrangle, White Pine County, Nevada
Author: Elizabeth L. Miller
Year: 2023
Series: Open-File Report 2023-04
Version:
Format: 28.5 x 27 inches, color
Scale: 1:24,000
The South Bastian Spring quadrangle includes the very southwestern tip of the northern Snake Range and the northwestern tip of the southern Snake Range. Bedrock exposure is minor compared to alluvium, but the geology of this quadrangle is an important component to the story of the northern Snake Range metamorphic core complex. North of Highway 50, exposures of Cambrian Prospect Mountain Quartzite and overlying Pioche Shale lie in low-angle fault contact with normal-faulted and tilted Paleozoic strata. The Prospect Mountain Quartzite is not lineated or foliated as is typical of the same unit in Snake Range metamorphic core complex, beneath the northern Snake Range detachment (NSRD) (e.g. Miller et al., 1999a). It is, however, highly brecciated, locally folded, and bedding readings show variability. We have interpreted the low-angle fault above the Pioche Shale in the South Bastian Spring quadrangle as the westernmost exposure of the northern Snake Range detachment fault. Here, unit contacts and foliation in the Pioche Shale beneath the mapped trace of the inferred NSRD are sub-parallel to it. To the south, in the northwestern exposures of rocks in the southern Snake Range, the Snake Range detachment fault as defined in the northern Snake Range ceases to exist, and Neoproterozoic to Cambrian age strata display original bedding (no mylonitic foliation or lineation) and are cut by normal faults. Faulting prevents knowledge of specific unit thicknesses in the South Bastian Spring quadrangle. Values cited are those listed in Miller et al. (1999b) based on previous stratigraphic work in the region.
This geologic map was funded in part by the USGS National Cooperative Geologic Mapping Program under STATEMAP award number G21AC10873, 2021.
Suggested citation:
Miller, E.L., 2023, Geologic map of the South Bastian Spring quadrangle, White Pine County, Nevada: Nevada Bureau of Mines and Geology Open-File Report 2023-04, scale 1:24,000, 3 p.
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