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[Scientist] William C Evans [Research Area] Geochemistry of Hydrothermal Systems show details View Publications [Science Topics] Geothermal Resources; Metals; Volcanic Hazards [Last Name] Evans [Details] 
Reconnaissance and chemical and isotope sampling of thermal springs in the western United States has not generally provided information of sufficient detail to permit the geothermal potential of most individual areas to be determined with any certainty. This is especially true in the Cascade Mountain Range, where the chemical geothermometers indicate much lower temperatures of water-rock equilibrium than the sulfate-isotope geothermometer and the geologic setting seem to require. This discrepancy could be due to simple mixing of thermal and fresh water or rapid equilibration of water with the surrounding country rock as the fluids rise to the surface; alternatively, the sulfate-isotopic composition could be an artifact reflecting the original source. In this project, the origin of the dissolved constituents, water, and gases discharging in the hot springs will be investigated, their relationship to the fumaroles and cold mineral springs ascertained, and recharge areas for the thermal springs and the amount of mixing of thermal and nonthermal waters will be determined. For additional informaition, see the Dynamics of Volcano-Hydrothermal Systems web site.
USGS National Research Program: NRP Scientists
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