Publisher： John Wiley & Sons Inc
E-ISSN： 2156-2202|92|B10|10427-10441
ISSN： 0148-0227
Source： Journal Of Geophysical Research, Vol.92, Iss.B10, 1987-09, pp. : 10427-10441
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Abstract
Gravity, magnetic, seismic refraction, electrical resistivity, and magnetotelluric measurements in northern Panamint Valley indicate that the alluvial and pluvial fill in the basin is thin and that basement under the valley floor lies at a shallow depth. Contours of the Bouguer gravity anomaly field do not define a low over the valley and do not mimic the mapped boundaries of alluvial fill. Electrical resistivity and seismic refraction measurements indicate that the playa in northern Panamint Valley is underlain by no more than about 200 m of sediment. This is consistent with the absence of any local lows in the Bouguer gravity anomaly field over the valley exceeding about 15 mGal in amplitude. There are no anomalies more than 50 nT in amplitude along an east‐west magnetic profile across the valley floor. In contrast, upward continuations of magnetic profiles measured across basalt outcrops present at the valley margins still contain anomalies exceeding 75 nT in amplitude at heights of 300 m. Because the inferred thickness of sediment under a width between 5 and 9 km of the valley is less than 300 m, it is insufficient to conceal the signal expected from such magnitized basalt buried under the sediment. We interpret this finding as indicating that the valley is not underlain by basalt except at its margins, which implies that the west side of the valley has moved between 6 and 10 km away from the Panamint Range, in a direction parallel to the Hunter Mountain fault (∼N55°W). A balanced cross section across the valley constrains the required low‐angle normal fault to be between 0.5 and 3 km beneath the valley floor.
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