Geothermal exploration with Hymap hyperspectral data at Brady–Desert Peak, Nevada

Abstract

We explore the use of Hymap (hyperspectral mapper) to remotely map unique geothermal indicator minerals over the Brady–Desert Peak geothermal fields. Geothermal-related minerals and rocks such as sinter, tufa, and sulfates, display diagnostic characteristics in the visible and shortwave infrared; their presence and distribution can be used to guide more detailed field work for geothermal exploration. The Brady–Desert Peak geothermal fields are located about 80 km east of Reno, Nevada in the Hot Springs Mountains. North–northeast-striking en-echelon faults offset Tertiary volcanic and lacustrine rocks. Two geothermal power plants produce electricity from two separate geothermal systems, one with numerous fumaroles and mudpots, the other showing no active surface expression of geothermal activity. Surface occurrences of gypsum, calcium–carbonate, hematite, and opaline silica were identified at both sites with the hyperspectral data; these minerals when considered together are indicative of geothermal activity at both sites. Mapping results were synthesized with other spatial data in a geographic information systems (GIS) database that was used to help draw structural interpretations of faulting and fault controls at the Brady–Desert Peak area. The same processing methods can be applied to new hyperspectral data sets for future exploration in the Great Basin, especially in areas that lack obvious thermal expressions.