Reduced Gas from Fracture Waters in Deep Gold Mines

Dissolved H2 concentrations up to the mM range and H2 levels up to 9 to 58% by volume in the free gas phase have been found in fractures waters 2 to 3 km below surface in the Precambrian crystalline rocks of Canada, Finland and South Africa.

Witwatersand Basin gold minesDissolved H2 concentrations up to the mM range and H2 levels up to 9 to 58% by volume in the free gas phase have been found in fractures waters 2 to 3 km below surface in the Precambrian crystalline rocks of Canada, Finland and South Africa. Along with previously reported dissolved H2 concentrations up to 7.4 mM for ground waters from the Witwatersrand Basin, South Africa, these findings indicate that deep Precambrian Shield fracture waters contain some of the highest levels of dissolved H2 ever reported and represent a important source of energy that sustains both the production of abiogenic organic synthesis through processes such as the Fischer-Tropsch synthesis, as well as supporting subsurface microbial life. In the Witwatersand Basin gold mines (pictured here), radiolysis has been demonstrated to be an important mechanism producing H2, while in the Archean greenstone belts of Canada and Finland, serpentinization of ultramafic rocks may be ancient analogs for serpentinite-hosted gases recently reported at the Lost City Hydrothermal Field and other active hydrothermal sea-floor deposits.

Credit T.C. Onstott Princeton University

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