We present 45 chemical and isotopic analyses from well discharges at The Geysers geothermal field and summarize the most notable geochemical trends. H2 and H2S concentrations are highest in the Southeast Geysers, where steam samples have δD and δ18O values that reflect replenishment by meteoric water. In the Northwest Geysers, samples are enriched in gas/steam, CO2, CH4, and N2/Ar relative to the rest of the field, and contain steam that is elevated in δD and δ18O, most likely due to substantial contributions from Franciscan-derived fluids. The δ13C of CO2, trends in CH4 vs. N2, and abundance of NH3 indicate that the bulk of the non-condensable gases are derived from thermal breakdown of organic materials in Franciscan meta-sediments.
|Title||Compilation of gas geochemistry and isotopic analyses from The Geysers geothermal field: 1978-1991|
|Authors||Jacob B. Lowenstern, Cathy Janik, Lynne Fahlquist, Linda S. Johnson|
|Publication Subtype||Journal Article|
|Series Title||Geothermal Resources Council Transactions|
|Record Source||USGS Publications Warehouse|