Three-Dimensional Geologic Characterization of a Great Basin Geothermal System: Astor Pass, Nevada

Title: Three-Dimensional Geologic Characterization of a Great Basin Geothermal System: Astor Pass, Nevada

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Abstract

The Great Basin, western USA, exhibits anomalously high heat flow (~75±5 mWm-2) and active faulting and extension, resulting in ~430 known geothermal systems. Recent studies have shown that steeply dipping normal faults in transtensional pull-aparts are a common structural control of these Great Basin geothermal systems. The Astor Pass blind (no surface expression) geothermal system, Nevada, lies along the boundary between the Basin and Range to the east and the Walker Lane to the west. Across this boundary, strain is transferred from dextral shear in the Walker Lane to west-northwest directed extension in the Basin and Range, resulting in a transtensional setting consisting of both northwest-striking, left-stepping dextral faults and northerly striking normal faults. Previous studies indicate that Astor Pass was controlled by the intersection of a northwest-striking dextral normal fault and north-northwest striking normal-dextral fault bounding the western side of the Terraced Hills. Drilling (to ~1200 m) has revealed fluid temperatures of ~94°C, confirming a blind geothermal system. Expanding upon previous work and employing interpretation of 2D seismic reflection data, additional detailed geologic mapping, and well cuttings analysis, a 3-dimensional geologic model of the Astor Pass geothermal system was constructed. The 3D model indicates a complex interaction/intersection area ofmore »« less

Authors:: Mayhew, Brett; Siler, Drew L; Faulds, James E

Publication Date:: 2013-09-30

Research Org.:: Rocky Mountain Rendezvous Student Expo

Sponsoring Org.:: USDOE; USDOE EE Office of Geothermal Technologies (EE-2C)

Contributing Org.:: Nevada Bureau of Mines and Geology, University of Nevada, Reno Mackay School of Earth Science and Engineering, University of Nevada, Reno

OSTI Identifier:: 1110510

Report Number(s):: DOE-Pyramid-2842-bm2

DOE Contract Number:: EE0002842

Resource Type:: Conference

Resource Relation:: Conference: Rocky Mountain Rendezvous of Geoscience Students and Employers

Country of Publication:: United States

Language:: English

Subject:: 15 GEOTHERMAL ENERGY; Geothermal, faults, Astor Pass, Pyramid Lake Paiute, 3D Geologic Model, structural controls, Great Basin

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                    Mayhew, Brett, Siler, Drew L, and Faulds, James E. Three-Dimensional Geologic Characterization of a Great Basin Geothermal System: Astor Pass, Nevada.  United States: N. p., 2013. 
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                    Mayhew, Brett, Siler, Drew L, & Faulds, James E. Three-Dimensional Geologic Characterization of a Great Basin Geothermal System: Astor Pass, Nevada.  United States.

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                    Mayhew, Brett, Siler, Drew L, and Faulds, James E. Mon .  
        "Three-Dimensional Geologic Characterization of a Great Basin Geothermal System: Astor Pass, Nevada".  United States.  https://www.osti.gov/servlets/purl/1110510.

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@article{osti_1110510,

  title        = {Three-Dimensional Geologic Characterization of a Great Basin Geothermal System: Astor Pass, Nevada},

  author       = {Mayhew, Brett and Siler, Drew L and Faulds, James E},

  abstractNote = {The Great Basin, western USA, exhibits anomalously high heat flow (~75±5 mWm-2) and active faulting and extension, resulting in ~430 known geothermal systems. Recent studies have shown that steeply dipping normal faults in transtensional pull-aparts are a common structural control of these Great Basin geothermal systems. The Astor Pass blind (no surface expression) geothermal system, Nevada, lies along the boundary between the Basin and Range to the east and the Walker Lane to the west. Across this boundary, strain is transferred from dextral shear in the Walker Lane to west-northwest directed extension in the Basin and Range, resulting in a transtensional setting consisting of both northwest-striking, left-stepping dextral faults and northerly striking normal faults. Previous studies indicate that Astor Pass was controlled by the intersection of a northwest-striking dextral normal fault and north-northwest striking normal-dextral fault bounding the western side of the Terraced Hills. Drilling (to ~1200 m) has revealed fluid temperatures of ~94°C, confirming a blind geothermal system. Expanding upon previous work and employing interpretation of 2D seismic reflection data, additional detailed geologic mapping, and well cuttings analysis, a 3-dimensional geologic model of the Astor Pass geothermal system was constructed. The 3D model indicates a complex interaction/intersection area of three discrete fault zones: a northwest-striking dextral-normal fault, a north-northwest-striking normal-dextral fault, and a north-striking west-dipping normal fault. These two discrete, critically-stressed intersection areas plunge moderately to steeply to the NW-NNW and probably act as conduits for upwelling geothermal fluids.},

  doi          = {},

  url          = {https://www.osti.gov/biblio/1110510},
  journal      = {},
number       = ,

  volume       = ,

  place        = {United States},

  year         = {2013},

  month        = {9}

}

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3D characterization of a Great Basin geothermal system: Astor Pass, NV

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The Great Basin exhibits both anomalously high heat flow (~75±5 mWm-2) and active faulting and extension resulting in robust geothermal activity. There are ~430 known geothermal systems in the Great Basin, with evidence suggesting that undiscovered blind geothermal systems may actually represent the majority of geothermal activity. These systems employ discrete fault intersection/interaction areas as conduits for geothermal circulation. Recent studies show that steeply dipping normal faults with step-overs, fault intersections, accommodation zones, horse-tailing fault terminations and transtensional pull-aparts are the most prominent structural controls of Great Basin geothermal systems. These fault geometries produce sub-vertical zones of high fault andmore »« less
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