Oxygen Isotope Geothermometry of Diagenetically Altered Shales

Abstract

The maximum temperature to which a shale has been heated as a result of burial can, in some instances, be estimated using oxygen isotope geothermometry. The isotopic fractionation, or difference between O^(18)/O^(16) ratios of two coexisting minerals which have reached isotopic equilibrium with one another, is temperature dependent. Hence, if two coexisting minerals, which have isotopically equilibrated with one another, can be separated from a shale, and if the variation of the equilibrium isotopic fractionation between these minerals is known, the temperature of equilibration can-be estimated.

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