Geothermal Exploration Using Hyperspectral Analysis Over Dixie Valley and Fairview Valleys, Nevada

Authors: Lamb, Amie; Kratt, Chris; Calvin, Wendy
Keywords: Hyperspectral remote sensing; HyMap; Hydrothermal mineralogy; Elevenmile Canyon; Dixie Meadows; Pirouette Mountain
Conference: Geothermal Resources Council Transactions Session: Exploration; Remote sensing; Geological surveys; Hydrotherma
Year: 2011 Language: English
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Abstract: Two hyperspectral data sets were acquired over Dixie Valley and several other smaller adjacent basins that totaled more than 1700 km2 of coverage. Hyperspectral analysis permits rapid identification of geothermal indicators such as hydrothermal alteration minerals and evaporite deposits over large surface areas. The hyperspectral data were acquired at 3m spatial resolution with 125 channels across the visible-near infrared and short-wave infrared wavelength regions. Data were collected over the northern portion of the valley in 2002 as part of a program sponsored by Lawrence Livermore National Lab. Our analysis of the 2002 data focuses on areas that have not been previously mapped. The second data set was funded by the Department of the Navy Geothermal Program Office, and acquired in September of 2010. Mineral maps were provided by the data vendor for the area covered in 2010 and augmented by our own analysis. The study area spans the southern portion of Dixie Valley and northern Fairview Valley, located in Churchill County, Nevada approximately 60 air kilometers northeast of Fallon. Eleven geothermal prospects have been identified by high temperatures in shallow temp gradient wells, hot springs, and fumaroles along the entire extent of Dixie Valley. The Dixie Valley Geothermal System is the hottest known system in Nevada with temperatures above 285?C at 3 km depth and a 63 MW power plant in the northern part of the valley that has been operational for over 30 years. Dixie Meadows and Coyote Canyon prospects are in exploratory drilling stages with plans for powerplant construction by Ormat, Inc. and Terra-gen, respectively, each with a predicted 62 MW output. Stillwater and Salt Wells geothermal plants are also within 25 km to the west of our study areas, though the geothermal systems are not necessarily related to the Dixie Valley prospects. Comparing the hyperspectral data with known areas of high heat flow and analysis from other data sets (shallow-temperature surveys and LiDAR) we identified three regions for initial detailed examination, Elevenmile Canyon, Pirouette Mountain and Fairview Peak. Hyperspectral mineral mapping indicated two additional areas of interest in La Plata Canyon and eastern Dixie Meadows. We identified areas with hydrothermal alteration including kaolinite, alunite, opal, chlorite, and gypsum.
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