Abstract
Measurements were made of the amounts of D,18O, and H2O+ in fault gouge collected over a depth of 400 m in the San Andreas fault of California. The amounts and isotopic compositions of the pore fluids, also analyzed, suggest that formation waters from adjacent Franciscan rocks have migrated into the gouge and mixed with local meteoric water. Thus the gouge is an open system permeable to fluid flow. This permeability has important implications concerning heat flow along the fault zone.
Analyses of the fault gouge itself give information on the amounts, timing, and conditions of formation of the clay minerals.
Stable-isotope analyses of materials from fault zones are good indicators of water-rock interactions that bear importantly on processes taking place in seismically active regions.
Similar content being viewed by others
References
Clauer, N. (1981),Rb−Sr and K−Ar Dating of Precambrian Clays and Glauconites, Precamb. Res.15, 331–352.
Craig, H. (1961),Isotopic Variations in Meteoric Waters, Science133, 1702–1703.
Dansgaard, W. (1964),Stable Isotopes in Precipitation, Tellus116, 436–467.
Lawrence, J. R., Gieskes, J. M., andBroecker, W. S. (1975),Oxygen Isotope and Cation Composition of DSDP Pore Waters and the Alteration of Layer II Basalts, Earth Planet. Sci. Lett.27, 1–10.
Lawrence, J. R., andTaylor, H. P., Jr. (1971),Deuterium and Oxygen-18 Correlation: Clay Minerals and Hydroxides in Quaternary Soils Compared to Meteoric Waters, Geochim. Cosmochim. Acta35, 993–1003.
Masi, U., O'Neil, J. R., andKistler, R. W. (1981),Stable Isotope Systematics in Mesozoic Grani Central and Northern California and Southwestern Oregon, Contrib. Min. Pet.76, 116–126.
Morrow, C. A., Shi, L. Q., andByerlee, J. D. (1982),Strain Hardening and Strength of Clay-Rich Fault Gouges, J. Geophys. Res.87, 6771–6780.
O'Neil, J. R.,Stable Isotope Geochemistry of Rocks and Minerals, in Lectures in Isotope Geology (eds E. Jager and J. C. Heinziker) (Springer-Verlag, Heidelberg, 1979), pp. 235–263.
O'Neil, J. R., andKharaka, Y. K. (1976),Hydrogen and Oxygen Isotope Exchange Reactions Between Clay Minerals and Water, Geochim. Cosmochim. Acta40, 241–246.
Savin, S. M., andEpstein, S. (1970),The Oxygen and Hydrogen Isotope Geochemistry of Clay Minerals, Geochim. Cosmochim. Acta34, 25–42.
White, D. E., Barnes, I., andO'Neil, J. R. (1973),Thermal and Mineral Waters of Non-Meteoric Origin, California Coast Ranges, Geol. Soc. Amer. Bull.84, 547–560.
Author information
Authors and Affiliations
Rights and permissions
About this article
Cite this article
O'Neil, J.R. Water-rock interactions in fault gouge. PAGEOPH 122, 440–446 (1984). https://doi.org/10.1007/BF00874610
Received:
Revised:
Accepted:
Issue Date:
DOI: https://doi.org/10.1007/BF00874610