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Three-dimensional geologic map of the Brady geothermal area, Nevada

April 15, 2021

The three-dimensional (3D) geologic map characterizes the subsurface in the Brady geothermal area in the northern Hot Springs Mountains of northwestern Nevada. We built the 3D map by integrating the results from detailed geologic mapping, seismic-reflection, potential-field-geophysical, and lithologic well-logging investigations completed in the study area. This effort was undertaken to investigate the geologic structure in the geothermal field and geologic controls on hydrothermal circulation. This characterization of the controls on hydrothermal circulation is applicable to the assessment, exploration, and development of analogous geothermal resources. The 3D map area is 4 kilometers (km) wide along the west-northwest-to-east-southeast axis and 6 km wide along the north-northeast-to-south-southwest axis and extends to 1.0 km below sea level, approximately 2.5 km below the land surface. We describe the geologic units and structures in the map area, discuss the methods used to integrate the geologic and geophysical information into the 3D geologic interpretation, and calculate several geologic factors that may aid in our understanding of hydrothermal circulation. Map sheet 1 provides horizontal and vertical section views and oblique perspective views from several angles of the 3D geologic map. Map sheet 2 provides views of derivative calculations based on the 3D geologic data, 3D density of faults, 3D density of fault intersections and terminations, slip tendency on 3D faults, and dilation tendency on 3D faults. We provide digital data for all elements of the map, such as individual 3D fault and stratigraphic surfaces, 3D fault density, 3D fault intersection density, 3D slip tendency on fault surfaces, and 3D dilation tendency on fault surfaces. A brief movie displaying the 3D map is available at https://doi.org/10.3133/sim3469.