Heat Flow and Geothermal Assessment of the Escalante Desert, Southwestern Utah, With Emphasis on the Newcastle KGRA
Twenty-five new regional heat flow measurements are presented for the Escalante Desert region within the Great Basin of the western U.S. Heat flow excluding geothermal areas ranges from 42 to 350 mW m -2 but much of the variability may be caused by deeply circulating groundwater redistributing the regional flux. A subset of 10 sites drilled specifically to characterize the heat flow of the region yielded a mean of 100 mW m -2 with a standard deviation of 22 mW m -2. An analysis of thermal conductivities of solid cylindrical discs and rock chips of rhyolite to andesite tuffs emphasized the importance of porosity corrections to thermal conductivity measurements.
A "blind" geothermal system southwest of Newcastle, Utah, situated within the Escalante Desert has also been studied. Heat flow results from 11 local drillholes yield values between 163 and 3065 mW m -2. The 500 mW m -2 coutour encloses an area of 0.4 km2. By integrating the anomalous flux above background over the thermal anomaly, a thermal power loss of 12.8 MW and corresponding subsurface mass discharge of 32 kg s -1 are calculated for this geothermal system.