This 27-page report analyzes new detailed (1:12,000 scale) geologic mapping of a 14 square mile area centered by the high-temperature (350°F) Sulphurdale heat source, which at the surface makes up a circular area about a mile in diameter that is likely caused by a magma body at depth. A former small steam-driven geothermal electric power plant in the circular area is being replaced by a larger plant (Enel Green Power North America) that will use binary technology. Five cross sections tied to and at the same scale as the map help interpret the likely extent of the geothermal resource. Sulfur derived from evaporites at depth was initially mined at a solfatara above the heat source; associated sulfuric acid seeped downward to remove the Kaibab Limestone and Toroweap Formation from the subsurface.

This 23 page report is an initial investigation into the role that low-angle faulting may play in the formation of the Thermo Hot Springs Known Geothermal Area (KGRA), within the Sevier geothermal anomaly of southwestern Utah. The stratigraphy and structures exposed in the southern mineral mountains are used as an analog for studying the subsurface stratigraphy and the detachment fault within the Thermo Hot Springs KGRA.

Past exploration in low- and moderate-temperature systems of the Great Basin shows that the relatively small area associated with fluid upflow and elevated temperatures is often difficult to detect by drilling widely spaced temperature-gradient holes or by other methods. By studying the Newcastle geothermal system, we hoped to develop a basic understanding of the concealed hydrothemlal system as a tool for assessing other geothermal areas of the Great Basin. The emphasis of our work centered on determining (1) the distribution of subsurface heat and the movement of thermal fluid, (2) the location and geometry of bedrock structures that might control fluid movements, (3) the chemical character of the geothermal water, and (4) the geometry of the bedrock beneath the Escalante Desert. Field studies included: (1) drilling and monitoring temperatures in shallow themlal-gradient boreholes, (2) mapping geologic units and performing structural studies in the adjacent mountains, (3) conducting detailed gravity surveys, (4) conducting electrical resistivity and self-potential (SP) surveys, (5) collecting water samples for detennining major ions and light stable isotope analyses, and (6) mapping Quaternary units.

This CD contains a 63 p. report of the task force to identify and promote the development of renewable energy resources to meet the goal of 20 percent of Utah's electrical retail sales by 2025. Work groups were established to identify energy zones for wind, solar, and geothermal energy resources. The Phase I report identifies energy zones (approx. 13,262 sq. miles) and an estimated 837 gigawatts of electrical generating capacity.

This report describes the geology of the central Virgin River basin in southwestern Utah, and characterizes the structure and lithology of the Jurassic Navajo Sandstone and the thickness and stratigraphy of Quaternary-late Tertiary unconsolidated deposits, the two main aquifers in the region. Southwestern Utah has experienced rapid population growth and increased demand on water supplies during the past 15 years, and the purpose of this report is to better define the ground-water resources of the area. Ground water provides approximately half of the public water supply in southwestern Utah, so future decisions regarding water use must be based on careful geologic characterization of the aquifers and their relation to the regional hydrologic system. The results of this study will be applied to ground-water modeling, evaluating regional and local hydrogeologic conditions, and assessing sites for development of ground water. 53 pages + 7 plates