Microbial impacts on geothermometry temperature predictions

Abstract

Conventional geothermometry approaches assume that the composition of a collected water sample originating in a deep geothermal reservoir still reflects chemical equilibration of the water with the deep reservoir rocks. However, for geothermal prospecting samples whose temperatures have dropped to 5 orders of magnitude. As a first test with actual field samples, the assay was applied to DNA extracted from water collected at springs located in and around the town of Soda Springs, Idaho. Soda Springs is located in the fold and thrust belt on the eastern boundary of the track of the Yellowstone Hotspot, where a deep carbon dioxide source believed to originate from Mississippian limestone contacts acidic hydrothermal fluids at depth. Both sulfate and sulfide have been measured in samples collected previously at Soda Springs. Preliminary results indicate that sulfate reducing genes were present in each of the samples tested. Our work supports evaluation of the potential for microbial processes to have altered water chemistry in geothermal exploration samples