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- James E. Faulds, Garrett S. Vice, Melissa L. Edwards, Mark F. Coolbaugh, "Characterizing Structural Controls of Geothermal Fields in the Northwestern Great Basin: A Progress Report,"
- Abstract: Considering a lack of recent volcanism, the abundant geothermal activity in the northwestern Great Basin is somewhat anomalous. The prolific activity may result from enhanced dilation on N- to NNE-striking normal faults induced by a transfer of NW-directed dextral shear from the Walker Lane to NW-directed extension in the Great Basin. Although faults control most geothermal activity in the Great Basin, few detailed investigations have been conducted on the specific structural controls of individual fields. Because knowledge of such structures would facilitate exploration models, we have embarked upon a regional study of the controls on geothermal activity, which includes detailed analysis of several fields, reconnaissance studies of many other fields, and compilation of existing data. Our findings from the Bradys, Desert Peak, Needle Rocks, Salt Wells, and Gerlach geothermal systems suggest that many fields occupy discrete steps in fault zones or lie in belts of intersecting, overlapping, and/or terminating faults. In addition, most fields are associated with steeply dipping faults and, in many cases, with Quaternary faults. The structural settings favoring geothermal activity all involve subvertical conduits of highly fractured rock along fault zones oriented approximately perpendicular to the least principal stress. Features indicative of these settings that may be helpful in guiding exploration include: 1) major steps in range-fronts, 2) interbasinal highs, 3) mountain ranges consisting of relatively low, discontinuous ridges, and 4) lateral terminations of mountain ranges.