Prospecting for a Blind Geothermal System Utilizing Geologic and Geophysical Data, Seven Troughs Range, Northwestern Nevada
GRC Transactions, Vol. 38, 2014 Prospecting for a Blind Geothermal System Utilizing Geologic and Geophysical Data, Seven Troughs Range, Northwestern Nevada Corina Forson1, James E. Faulds1, and Phil Wannamaker2 1Nevada Bureau of Mines and Geology, University of Nevada, Reno NV 2Energy and Geoscience Institute, University of Utah, Salt Lake City UT Keywords resources. Researchers estimate that only ~20% of the accessible Nevada, Basin and Range, structural controls, Seven Troughs geothermal resources in the Great Basin have been discovered, Range, blind geothermal system, exploration, geologic map- suggesting that opportunities abound for discovering blind or ping, Magnetotelluric, two-meter survey hidden geothermal systems (Brook et al., 1979; Richards and Blackwell, 2002). If prospecting for a truly blind geothermal system, it becomes Abstract important to distinguish between a blind, hidden, and conventional geothermal resource. All geothermal systems have three main The Seven Troughs Range in Pershing County, Nevada, has elements: heat source (magmatic or high geothermal gradient in been identified as an area with high potential for hosting a blind amagmatic settings), reservoir (to hold and sustain the hot water), geothermal system. A reconnaissance 2D magnetotelluric (MT) and fluid, which is the medium that transfers the heat. Conven- survey across the western U.S. has shown a possible correlation tional geothermal systems exhibit fluid surface manifestations, between broad low resistivity anomalies, extending from the up- such as fumaroles or hot springs. Hidden geothermal systems per to deep crust, and loci of high enthalpy geothermal systems. lack fluid features on the surface but contain more subtle features Where MT surveys have been conducted across the Basin and (or paleo manifestations), such as siliceous sinter, travertine, tufa Range, anomalous zones of high conductivity strongly correlate deposits, and/or hydrothermally altered rocks.
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