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Exploring for fault-hosted geothermal systems using low temperature thermochronometry and thermo-kinematic modeling

False-colored shaded relief map of major fault system in western Alaska selected for pilot study (image courtesy of Zanskar Geothermal & Minerals, Inc.).

Elizabeth Miller and Martin Grove, Geological Sciences 

Geothermal energy is a vastly underutilized source of carbon-free power whose development remains hindered by significant pre-drilling uncertainty. Many of the fault-hosted geothermal systems producing power today had no obvious surface manifestation such as hot springs, fumaroles, or sinter mounds, and were discovered only by accident. A critical uncertainty when exploring for these types of “blind” geothermal systems is whether a recently active fault mapped at the surface remains permeable at depth and is acting as a dominant pathway for hydrothermal circulation or whether natural processes have sealed the fault since its last rupture. Mineral thermochronometry, which can deduce the temperature history of rocks, when paired with thermo-kinematic modeling offers a promising means to constrain the extent and duration of even blind and/or transient hydrothermal events within a fault zone. This study will apply these methods to a regional fault system in western Alaska which has not been tested for its blind geothermal potential. If successful, this study would aid ongoing exploration work in the region aimed at meeting the energy needs of remote Arctic communities. And, more broadly, it would help refine and demonstrate this potentially cost-effective exploration tool for use in geothermal exploration programs around the globe.

Awarded 2019