Detailed Analysis of Geothermal Potential in Crescent Valley, North-Central Nevada
AuthorMcConville, Emma Grace
AdvisorFaulds, James E
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This study has synthesized geological, geochemical, and geophysical data sets to elucidate the structural architecture and history of the Crescent basin in order to assess its geothermal potential. The Crescent basin is a complex composite basin, consisting primarily of multiple east-tilted half grabens and horst blocks bounded by several major faults of variable strike. Fault kinematic data indicate a present-day west-northwest-trending least principal stress, which in turn suggests that north-northeast-striking normal faults have relatively high slip and dilation tendency. However, a protracted history of changing Cenozoic extension directions has produced a mosaic of fault patterns, which has generated both segmented fault geometries and multiple fault intersections. These structural complexities have ultimately primed the basin for geothermal activity. Detailed analyses and application of the play fairway methodology have respectively denoted and ranked 12 favorable structural settings capable of hosting geothermal fluids in the Crescent basin. Of the 12 favorable structural settings, five were identified as having a higher likelihood of hosting a relatively high-temperature (>130°C) geothermal system, including Hand-Me-Down Creek, Hot Springs Point, and three other unnamed areas. The Hand-Me-Down Creek hybrid structural setting along the Crescent Valley fault is the only documented relatively high temperature geothermal system identified in the basin. It contains an active 87°C hot spring actively depositing sinter and geothermometry greater than 170°C (possibly >180°C). Future exploration efforts at Hand-Me-Down Creek would benefit from focusing on targeting high permeability zones at depth utilizing densely spaced electromagnetic surveys, fluid flow modeling, and selective drilling that targets specific fault intersections within the greater step-over at depth. The Hot Springs Point hybrid structural setting along the Dry Hills fault hosts a geothermal system, but geothermometry, spring temperatures, and well temperatures indicate that fluids do not exceed ~100°C. Three other relatively promising areas include a fault intersection in the central part of the basin and two step-overs (relay ramps) along the Crescent Valley fault, but additional exploration is needed at these sites, such as 2-m temperature surveys in the dry season, measuring deeper subsurface temperatures through temperature-gradient drilling, and collecting water samples through geoprobe drilling to estimate geothermometry.