Dissolved gases in the DOSECC Cajon Pass well: First year results

Geophysical Research Letters
By: , and 

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Abstract

Fluid sampled from granitic rock near the 2 km depth in the DOSECC Cajon Pass well contained He, H2, CH4, C2H6, and C2H4 in concentrations much greater than in air-saturated water. The dissolved helium, which ranged in concentration from 0.6 to 0.8 µmole/kg-fluid, was almost entirely radiogenic (³He/4He = 0.06 Ra). The δ13C-CH4 value (−36 per mil) and (C2H6 + C2H4)/CH4 ratios (0.02 - 0.05) indicate that the dissolved methane (50-55 µmoles/kg-fluid) was produced by thermogenic breakdown of organic matter. Measured pCO2 values were very low, about 10−5 atm., and the carbon isotopes (δ13C = −18.9 per mil) point to an organic source such as plant root respiration for the dissolved carbonate species. No evidence of mantle volatiles was found despite proximity of the well to the San Andreas fault.

Publication type Article
Publication Subtype Journal Article
Title Dissolved gases in the DOSECC Cajon Pass well: First year results
Series title Geophysical Research Letters
DOI 10.1029/GL015i009p01041
Volume 15
Issue 9
Year Published 1988
Language English
Publisher American Geophysical Union
Description 4 p.
First page 1041
Last page 1044
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