Geothermal Site Assessment using the National Geothermal Data System (NGDS), with Examples from the Hawthorne Ammunition Depot Area

Abstract

The Nevada Bureau of Mines and Geology and Great Basin Center for Geothermal Energy have compiled nearly 50,000 Great Basin groundwater samples into an Access database, encompassing all known spatial, physical, and geochemical features. The database schema is a partial template for the National Geothermal Data System (NGDS), a DOE-sponsored compendium of geothermal data spanning all 50 states. The database can be queried to produce worksheets customized to user requirements, greatly simplifying data extraction for other software applications (e.g., GoogleEarth). This paper examines the features and functionality of the existing database, its integration into the 50-state NGDS, and its usage in geothermal exploration and development. In particular, we examine the dataset for Hawthorne, NV, which has been supplemented extensively by the Naval Geothermal Program Office and subcontractor Epsilon Systems Solutions, Inc. As we demonstrate, a database user can identify Hawthorne-area thermal anomalies several ways: through spatial interpolation of database geothermometry, temperature gradient calculations, and other geochemical signatures. The ratios of B/Cl, Li/Cl, and As/Cl may identify zones of geothermal potential, as can regional patterns of total dissolved solids, Na-K-Ca ternary diagrams, and trace element ternary diagrams.