Origin and chemical evolution of the Geysers, California, hydrothermal fluids: Implications from fluid inclusion gas compositions
- Univ. of Utah, Salt Lake City, UT (United States)
- New Mexico Tech, Socorro, NM (United States); and others
The compositions of fluid-inclusion gases from hydrothermally altered rocks at The Geysers were determined to evaluate their origins. Samples dominated by magmatic fluids have N{sub 2}/Ar ratios much greater than air and high {sup 3}He/{sup 4}He ratios. Fluid inclusion populations dominated by connate waters also have high N{sub 2}/Ar ratios but are enriched in CH{sub 4}. A noble gas analysis of one sample indicates that it has high contents of radiogenic He and a low R/Ra ratio. These samples are found mainly in the northwest Geysers. Samples from the southeast and central Geysers generally have N{sub 2}/Ar ratios between air and air-saturated water indicating a significant component of meteoric recharge, and lower CH{sub 4} contents. Despite their meteoric signature, He isotopic compositions record the influence of a magmatic input. Similar N{sub 2}-Ar-CH{sub 4} ratios characterize the modem steam.
- DOE Contract Number:
- AC03-76SF00098
- OSTI ID:
- 602784
- Report Number(s):
- CONF-971048--
- Country of Publication:
- United States
- Language:
- English
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