Analysis of remote sensing data for geothermal exploration over Fish Lake Valley, Esmeralda County, Nevada

The purpose of this study was to identify and map hydrothermal alteration and geothermal deposits in northern Fish Lake Valley, Nevada using both visible, near, shortwave infrared (0.4-2.5 µm) and thermal infrared (8-12 µm) remote sensing data. Visible, near, and shortwave infrared data were collected by four airborne instruments including NASA's Airborne Visible/Infrared Imaging Spectrometer (AVIRIS) and MODIS-ASTER (MASTER) instruments, HyVista Corporation's HyMap sensor, and SpecTIR Corporation's ProSpecTIR instrument. MASTER also collected thermal infrared data over Fish Lake Valley. Hydrothermal alteration minerals and hot spring deposits were identified using diagnostic spectra extracted from the remote sensing data. Mapping results were verified in the field using a portable spectrometer. Two areas of opaline sinter and travertine deposits were identified west of the Fish Lake Valley playa. Field observation reveals the alternating nature of these beds, which likely reflects fluctuating hot spring fluid chemistries. Sinter and travertine were likely deposited around fault-related hot springs during the Pleistocene when the water table was higher. Previously undiscovered Miocene crystalline travertine was identified within the Emigrant Hills near Columbus Salt Marsh. Argillic alteration was mapped in parts of the ranges surrounding Fish Lake Valley. Kaolinite, and to a lesser extent, muscovite and montmorillonite, were used as indicator minerals for argillic alteration. In these regions, thermal fluids were likely discharged from faults to alter rhyolite tuff. Mineral maps were synthesized with previously published geologic data and used to delineate four new targets for future geothermal exploration. The abundant hot spring deposits along the edge of the Volcanic Hills combined with argillic alteration minerals mapped in the ranges suggest geothermal influence throughout much of the valley