Intersecting Fault Trends and Crustal-Scale Fluid Pathways Below the Dixie Valley Geothermal Area, Nevada, Inferred from 3d Magnetotelluric Surveying

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Conference Paper: Intersecting Fault Trends and Crustal-Scale Fluid Pathways Below the Dixie Valley Geothermal Area, Nevada, Inferred from 3d Magnetotelluric Surveying

Abstract
Geothermal systems may occur in zones of structural dilatency which create the crustal plumbing that al-lows concentration of high-temperature fluids from surrounding volumes. While structural orientations of the U.S. Great Basin are dominated visually by the NNE-oriented horst-graben morphology, other alignments are apparent, perhaps principally a NNW-trending grain related to early-stage Great Basin ex-tension. As part of an integrative research project to establish Engineered Geothermal Systems (EGS) methodology at district scales for high-enthalpy ex-tensional systems, a 3D magnetotelluric (MT) resis-tivity survey of 94 tensor stations was acquired over the Dixie Valley geothermal system and has under-gone 3D inversion analysis. Part of the motivation for the MT study was the observation in earlier 2D MT transect data of a large-scale, low-resistivity (conduc-tive), presumably fluidized crustal fault zone con-necting interpreted deep magmatic underplating nearby to the west under Buena Vista Valley with the Dixie Valley geothermal system, consistent with he-lium isotope studies. The 3D inversion model largely confirms the 2D structure, albeit not surprisingly with a more complicated geometry. Primarily, the 3D model exhibits an intersection of NNE graben fill and range-bounding conductive trends with deeper, NNW conductors. These conductors are believed to repre-sent zones of saline fluids whose collection is pro-moted by opening of these structural trends with the ongoing extension of the Great Basin through this area. The collection of intersections as a group equates to the previously identified 2D crustal break and plunge steeply west beneath the Stillwater Range. Visually, these structural conduits coalesce toward the lower crust and dip westward toward Buena Vista valley and the deep magmatic activity.

Authors 
Phil Wannamaker, Virginie Maris, Jon Sainsbury and Joe Iovenitti






Conference 
PROCEEDINGS, Thirty-Eighth Workshop on Geothermal Reservoir Engineering; Stanford University; 2013


Published 
PROCEEDINGS, Thirty-Eighth Workshop on Geothermal Reservoir Engineering;, 2013





DOI 
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Online 
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Citation

Phil Wannamaker,Virginie Maris,Jon Sainsbury,Joe Iovenitti. 2013. Intersecting Fault Trends and Crustal-Scale Fluid Pathways Below the Dixie Valley Geothermal Area, Nevada, Inferred from 3d Magnetotelluric Surveying. In: PROCEEDINGS, Thirty-Eighth Workshop on Geothermal Reservoir Engineering. PROCEEDINGS, Thirty-Eighth Workshop on Geothermal Reservoir Engineering; 2013; Stanford University. Stanford University: (!) ; p. (!)


Related Geothermal Exploration Activities
Activities (1)


Areas (1)
  1. Dixie Valley Geothermal Area
Regions (0)