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Dilation brecciation: proposed mechanism of fracturing, petroleum expulsion, and dolomitization in Monterey formation, California

Conference · · Am. Assoc. Pet. Geol., Bull.; (United States)
OSTI ID:5592924
The Monterey formation has been replaced selectively by dolomite and subsequently fractured, brecciated, and relithified with several generations of dolomite cement. The 2 dolomite types are distinctive in morphology, color, stoichiometry, ..delta.. C/sup 13/, ..delta.. O/sup 18/, as well as insoluble and trace element content. Dilation breccias evidently originate in embrittled rocks through a distinctive sequence of steps induced by tectonism: dilatancy, fluid expulsion, natural hydraulic fracturing, brecciation, hydroplastic flow, injection, and dolomite precipitation. Development is most abundant in, but not restricted to, areas of strike-slip faulting. Tectonic stresses cause an initial compression and subsequent dilation (elastic) of rock microcracks and imperfections. With continued stress, the cracks are propagated inelastically and develop into major fracture networks. Fracturing associated with excess pore fluid pressures triggers an instantaneous flow of connate fluids across several hundred feet of newly fractured strata.
OSTI ID:
5592924
Report Number(s):
CONF-8105250-
Conference Information:
Journal Name: Am. Assoc. Pet. Geol., Bull.; (United States) Journal Volume: 65:5
Country of Publication:
United States
Language:
English