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Electrical conductivity images of Quaternary faults and Tertiary detachments in the California Basin and Range

Park, Stephen K. and Wernicke, Brian (2003) Electrical conductivity images of Quaternary faults and Tertiary detachments in the California Basin and Range. Tectonics, 22 (4). Art. No. 1030. ISSN 0278-7407. doi:10.1029/2001TC001324.

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Comparison of an electrical resistivity section derived from magnetotelluric (MT) data to a geologic section extending eastward from the Sierra Nevada near latitude 36°20′N shows that the crust is dominated by steeply dipping conductive features that correlate with active strike-slip faults. While there is a subhorizontal conductor at a depth ∼20 km beneath some of the profile, it is broken by vertical structures associated with the active strike-slip faults. The continuous subhorizontal anomalies in the lower crust typically observed in extensional regions are therefore absent in the resistivity section. The present-day strike-slip tectonic regime as indicated by geodetic data in this part of the Basin and Range is not producing features that could be inferred to indicate subhorizontal shear zones resulting from lateral crustal flow during extension. Because the Miocene tectonic regime resulted in the formation of metamorphic core complexes and thus was accompanied by such flow, the present regime appears to represent a fundamental transition in the mode of crustal deformation in the region. A serendipitous result of our study was the identification on resistivity sections of carbonate aquifers in the upper crust. Comparison of resistivities from the MT section to measured fluid resistivities from springs and boreholes suggests that the aquifers must be heterogeneous, with more saline brines occupying the deepest portions of the carbonates.

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Wernicke, Brian0000-0002-7659-8358
Additional Information:© 2003 The American Geophysical Union. Received 4 September 2001; Revised 4 August 2002; Accepted 27 August 2002; Published 9 July 2003. Support from the National Science Foundation’s Continental Dynamics Programs under grants EAR9526992 (S. K. Park) and EAR9526895 (B. Wernicke) is gratefully appreciated. Broadband data acquisition was supervised by George Jiracek for MT stations 101– 130. Robert Bielinski, Scott Elrick, and Richard Funk helped in the data acquisition for the long period stations in 1997. We also thank Death Valley National Park and Sequoia-Kings Canyon National Park scientists for their assistance in this study. Reviews by Phillip Wannamaker, John Booker, and Associate Editor Darrel Cowan helped improve this manuscript greatly.
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Subject Keywords:magnetotellurics; Basin and Range; Death Valley; detachment faults
Issue or Number:4
Record Number:CaltechAUTHORS:20140718-152004214
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Official Citation:Park, S. K., & Wernicke, B. (2003). Electrical conductivity images of Quaternary faults and Tertiary detachments in the California Basin and Range. Tectonics, 22(4), 1030. doi: 10.1029/2001tc001324
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:47351
Deposited On:21 Jul 2014 16:57
Last Modified:10 Nov 2021 17:38

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