Geochemical Evaluation of Geothermal Resources of Camas Prairie, Idaho

Abstract

The Camas Prairie in Blaine, Camas, and Elmore Counties, Idaho has long been identified as an area with geothermal potential, and is one of several promising geothermal prospects that were identified by play fairway analysis of the Snake River Plain region. The geothermal activity in the area is manifested by the presence of several hot springs. Moreover, a number of groundwater wells with elevated temperatures have been identified in the area. However, the location of geothermal resources within the basin is poorly constrained, as they are concealed by Quaternary and Neogene sedimentary deposits and volcanic rocks. The prairie is likely formed by failed rifting or extensional faulting as a response to the down warping of the central Snake River Plain to the south. Young volcanic activity and faulting are evident within the prairie and along its margins. As a part of a more comprehensive effort to assess the geothermal resource potential of the area, we present new water chemical and isotope results from the area in the context of existing water chemistry data. We applied conventional and multicomponent geothermometry tools to estimate the reservoir temperatures for the area. Specifically, our geochemical and geothermometry analysis indicated two interesting areas, one in the central-west northern side and other in the central-west southern side of prairie. Our results show that the Camas Prairie area could potentially host resources with temperatures as high as 200 ºC. Water chemical and isotopic results suggest that the highest temperature resource is a mixture between deeply circulated fluids with a magmatic affinity and local meteoric recharge. The water geochemistry suggests that there are two potential geothermal resource types: one associated with the Idaho Batholith to the north, and a second related to elevated heat flow associated with Quaternary volcanism and intrusions within the Snake River Plain province. Ongoing geophysical, geological, and geochemical investigation of the area could be instrumental in defining the Camas Prairie geothermal resource.