Fluid inclusion gas analysis for wells in Salton Sea geothermal area, California. Analyses used in developing fluid inclusion stratigraphy for wells and defining fluids across the geothermal fields. Each sample has mass spectrum counts for 180 chemical species.

Fluid inclusion gas analysis for wells in Glass Mountain geothermal area, California. Analyses used in developing fluid inclusion stratigraphy for wells and defining fluids across the geothermal fields. Each sample has mass spectrum counts for 180 chemical species.

Fluid inclusion gas analysis for wells in Fallon geothermal area, Nevada. Analyses used in developing fluid inclusion stratigraphy for wells and defining fluids across the geothermal fields. Each sample has mass spectrum counts for 180 chemical species.

Fluid inclusion gas analysis for wells in Beowawe geothermal area, Nevada. Analyses used in developing fluid inclusion stratigraphy for wells and defining fluids across the geothermal fields. Each sample has mass spectrum counts for 180 chemical species.

Fluid inclusion gas analysis for wells in Iceland. Analyses used in developing fluid inclusion stratigraphy for wells and defining fluids across the geothermal fields. Each sample has mass spectrum counts for 180 chemical species.

Fluid inclusion gas analysis for wells in Karaha Telga Bodegas geothermal reservoir, Indonesia. Analyses used in developing fluid inclusion stratigraphy for wells and defining fluids across the geothermal fields. Each sample has mass spectrum counts for 180 chemical species.

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The U.S. Geological Survey (USGS) compiled and analyzed data for mapping groundwater total dissolved solids (TDS) at the San Ardo Oil Field in Monterey County, California. Data include groundwater TDS and bicarbonate concentration from oil well and groundwater well samples, formation resistivity from borehole geophysical logs, porosity from well logs and rock core samples, temperature from water samples and well logs, selected oil well injection volumes, and geological formation depths. The data reported here are used in an accompanying manuscript (Stephens and others, 2025) that describes methods and results of mapping groundwater TDS. The modeled values from the related manuscript are also provided. A portion of these data were found in archived scanned pages in raster format on the California Geologic Energy Management Division (CalGEM) website (CalGEM, 2022) and have been compiled into machine readable numerical format. Other data, such as the geological layers, were generated during this project by interpreting borehole geophysical data from CalGEM (2022). All the data analyzed are part of the California State Water Resources Control Board Oil and Gas Regional Monitoring Program and the USGS California Oil, Gas, and Groundwater (COGG) program.

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Gas chemical and isotopic compositions are reported for samples collected from 9 volcanic and geothermal areas in California: Medicine Lake Volcano, Mount Shasta, Lassen Volcanic Center, Clear Lake Volcanic Field, Mono Lake Volcanic Field, Long Valley Caldera, Mammoth Mountain, Coso Volcanic Field, and Salton Sea Geothermal Field. Beginning in 2014, gas samples were collected as part of the USGS California Volcano Observatory's newly established gas geochemical monitoring program for moderate to very-high-threat volcanoes. Data on gas samples collected prior to 2014 by this and previously published studies are also reported to provide longer-term records for some areas. Gas samples in this study were analyzed for chemical (CO2, H2S, He, H2, Ar, O2, N2, NH3, CH4, C2H6, CO, C3H8, and C4H10) and isotopic (R/RA, d13C-CO2, d13C-CH4, dD-steam, d18O-steam) compositions at USGS laboratories in Menlo Park, California, Denver, Colorado, and Reston, Virginia. The chemical and isotopic data are saved in three spreadsheets in the *.csv format.