Current Research at the Great Basin Center
                                                     

Research at the Great Basin Center focuses on causative factors that control the formation of high-temperature geothermal systems in the Great Basin, which include tectonic strain, faulting, heat flow, and proximity to young silicic volcanic centers. In addition, remote sensing techniques and sampling geothermal waters provide insight into the location and characteristics of these hydrothermal systems. Our approach has been to find new ways to measure these processes, and then use sophisticated spatial modeling techniques to determine exactly how these factors combine to form geothermal systems. This is the first step in coming up with a predictive model that can identify high-temperature geothermal systems in locations where they either do not reach the surface or are masked by other near-surface geologic phenomena.
                                                     

Recent advances in GPS technology allow for very precise location measurements, which in turn can be used to detect subtle crustal movements and thus directly measure current ongoing crustal strain. Geoff Blewitt, Corne Kreemer, and Bill Hammond of the Nevada Geodetic Laboratory are accomplishing this by synthesizing data from several GPS networks and producing maps of shear and dilational strain for the Great Basin. Click here for more information.

            
                                   
                                                     
                  Gravity data can be filtered to emphasize near-surface gravity differences that help identify major through-going faults that serve as conduits for geothermal fluids. Similarly, satellite radar imagery (InSAR) can show areas of local ground subsidence or swelling associated with the removal or injection of geothermal fluids. Gary Oppliger of the Arthur Brant Laboratory for Exploration Geophysics ('ABLE Lab') is the primary researcher exploring this avenue.    
         
                                                     
       
Multispectral and hyperspectral satellite and airborne imagery can target geothermal systems by identifying the telltale reflectance patterns of characteristic minerals or vegetation. Wendy Calvin, Mark Coolbaugh, and Chris Kratt are establishing baseline readings at known geothermal systems and using this data to explore for undiscovered geothermal systems.      
                                                     
  The geochemistry of springs and wells can yield information about the temperature of the aquifer or reservoirs from which they came. Lisa Shevenell, Larry Garside, Mark Coolbaugh, and Paul Lechler continue to sample groundwater in the Great Basin to identify new thermal anomalies and establish reservoir geothermometer temperatures.      
                                                     
Mobile compounds such as mercury, carbon dioxide, helium, and ammonia occurring in geothermal systems can rise through pore spaces and up to the surface. This provides a potential method of detecting "blind" systems that have no obvious surface expression. Paul Lechler of the Nevada Bureau of Mines and Geology  used silver wires inside inverted funnels to detect mercury soil gas above the Desert Peak geothermal system (see Power Point presentation). Current research is directed towards refining the mercury technique and determining the effectiveness of measuring other gases in geothermal exploration.
       
                       
                                                     
Crustal strain and regional extension causes normal faulting, which serve as conduits for hot, deep geothermal fluids to reach the surface. James Faulds of the Nevada Bureau of Mines and Geology studies the relationship between large scale tectonics and the smaller but locally very important structural controls to geothermal systems.    
                       
                 
                                                     
  What is the thickness of the crust underneath the Great Basin? Are there areas where thinner crust corresponds to higher heat flow and high-temperature geothermal systems? John Louie of the UNR Seismological Laboratory is finding out.    
                                                     
  A new spin on an old technique: Mark Coolbaugh, Chris Sladek, Chris Kratt, and Richard Zehner of the Great Basin Center are perfecting a method to rapidly measure temperatures at a two meter depth, below the zone of daily temperature variation. The method consists of pounding 1/2" hollow steel rods into the ground using a demolition hammer, inserting a resistive temperature device (RTD) into the rod, and then measuring the temperature after a short equilibration time (see Coolbaugh and others, 2007 and Sladek and others, 2007). This method works well in areas with thick soil horizons, such as alluvial valleys, but the rods have difficulty penetrating through cobbly soils or bedrock.

A pilot study was conducted in the Desert Queen geothermal area east of Desert Peak, where an old temperature gradient hole identified a thermal aquifer at ~70 m depth. A survey delineated a strong, consistent temperature anomaly at 2 meter depth in the vicinity of the temperature gradient hole. Work in other areas have discovered thermal anomalies in areas lacking thermal springs or wells. Click here for more information.

  
                                           
                                                     
    Last but not least, Mark Coolbaugh and Rick Zehner put these diverse data sets into a Geographic Information System (GIS) where it can be viewed and analyzed spatially. By comparing these data with known high-temperature geothermal systems using statistical models such as Weights of Evidence and logistic regression, predictive maps can be built showing areas of high geothermal potential.  
                   
 

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to see a list of current and past projects that have been funded by the Department of Energy.