Hydrothermal alteration of basin sediments and the chemical evolution of an extensional geothermal system, Humboldt House geothermal area, Pershing County, Nevada

Humboldt House geothermal area (HHGA), located in Pershing County Nevada, is part of an extensional Basin and Range geothermal system formed by deep-sourced hydrothermal fluids upwelling along a range-bounding fault zone. Mineralogical and geochemical analysis, conducted on the core from the P3-1 geothermal well to evaluate the hydrochemical processes that occurred during the evolution of the geothermal system, indicate that both advanced argillic alteration and silicic alteration have occurred at HHGA as a result of reducing, neutral hydrothermal fluids that spread laterally through the permeable alluvial sediments to form a boiling water table. Overprinting of steamheated, advanced argillic alteration by extensive silicic alteration suggests a vertical flow component to the hydrothermal fluids in the area around the P3-1 well. This indicates the area may have been closer to the fault zone than the other two geothermal well cores (P10-1 and P32-2) taken at HHGA.