EVALUATING A DEEP-CIRCULATION, FAULT-HOSTED HYDROTHERMAL SYSTEM: GREENFIELD EXPLORATION AT THE CARVERS GEOTHERMAL AREA, NEVADA, USA

Many hydrothermal systems worldwide are hosted by structural discontinuities along young or active faults. These structural features host higher density faulting and fracturing relative to the surrounding crust, and therefore serve as sub-vertical conduits for convective upwelling of geothermal fluids. In early-stage exploration for hydrothermal resources, characterizing the structural setting of upflow is critical to develop testable conceptual models of hydrothermal processes, estimate the size of the system, and guide future exploration. Here, we present the results of early-stage multidisciplinary geoscience exploration at the Carvers geothermal area in central Nevada. This work serves as a real-world case study of an exploration program as it progressed from review of legacy data and gap analysis, to implementation of additional exploration activities to fill key data gaps, to development of conceptual models and an exploration plan designed to test those models. The Carvers geothermal area is located in Big Smokey Valley in central Nevada and is associated with a ~2 km-long spring complex with spring discharge at ~40 – 100 °C from dozens of locations. Legacy data analyzed included temperature and temperature gradients of relatively shallow wells, spring and well fluid geochemistry data, gravity, ground magnetics, audio magnetotellurics (AMT) and active seismic geophysical data, and one relatively high flow rate (~1400 GPM) artesian well with a maximum flowing temperature of ~105 °C. The legacy data were augmented with new data collected and analyzed in 2023, which included LiDAR, gravity, magnetotelluric (MT), and fluid geochemistry data. Interpretation and integration of these datasets has yielded two equally permissible structurally-controlled conceptual models. Each model suggests that fluids with estimated temperatures of 150°C upwell in structural discontinuities along a newly defined fault system. In one model, the structural complexity is a stepover within the fault system, whereas in the other model, the northern termination of the fault localizes sub-vertical fluid flow. Future exploration will focus on differentiating between the two structurally-controlled conceptual models and moving the project further towards commercial development.