Geophysical investigation of hot springs within the vicinity of Shoshone, California

Abstract:

Hot springs in the Death Valley Region of California lie along the Amargosa River with distinct centers in Saratoga, Tecopa, Shoshone, and Beatty. A geophysical investigation of the hot springs in Tecopa and Saratoga led Wamalwa and other (2011) to hypothesize that deep faults must intersect with a specific orientation relative to the regional stress field in order to support hot springs along the Amargosa River. The inferred that one set of faults parallels the Amargosa River and trends northerly and the other set trends WNW to create an opening in the NW-SE oriented extensional stress field of the region. This research tests that hypothesis in the vicinity of Shoshone using magnetic and gravity data. Three isolated basalt mounds were identified in the area of the Shoshone hot springs. Two of these mounds are characterized by low magnetic and low Bouguer gravity anomalies. The third mound has high Bouguer gravity and high magnetic anomaly. This observation suggests that the basalt mounds were formed at different times and/or from different eruptive sequences. The alignment of the mounds and geophysical trends observed in the data support the earlier hypothesis and suggest there is a pair of faults trending north and west-northwest, respectively, in the area of the Shoshone hot springs. No other hot springs were located in the area but similar intersecting faults with the appropriate orientations were indicated by the geophysical data. We infer that either the basin sediments are sufficiently thick to prevent the springs from flowing to the surface or that the faults are not deep enough to tap the hot water that would produce a hot spring.