Pore pressure during metamorphism of carbonate rock: Effect of volumetric properties of H2O-CO2 mixtures

Theodore C. Labotka, Lawrence M. Anovitz, James G. Blencoe

Research output: Contribution to journalArticlepeer-review

9 Scopus citations

Abstract

The molar volume of mixtures of CO2 and H2O is a strong function of the fluid composition. Both CO2 and H2O participate in the metamorphism of carbonate rocks, resulting in a change in the fluid composition during reaction. One of the effects of the change in composition is the increase in pore-fluid pressure with only small increase in extent of reaction, ξ. Pressure calculated from the volumetric properties of CO2-H2O mixtures at 400 °C increases greatly with small increases of ξ but drops at greater values because of the increase in pore volume as a result of Δ solid. The pore pressure increase at small values of ξ, though, readily exceeds the reported tensile strength of carbonate rocks, and the rock cannot sustain significant reaction without fracturing. The result of a small amount of reaction is a fractured rock with increased permeability, which promotes fluid transport.

Original languageEnglish
Pages (from-to)305-313
Number of pages9
JournalContributions to Mineralogy and Petrology
Volume144
Issue number3
DOIs
StatePublished - Dec 2002

Funding

Acknowledgements Research on the properties of metamorphic fluids has been supported in part by National Science Foundation grant EAR-0106990. Funding for J.G.B. was provided by the Division of Chemical Sciences, Geosciences, and Biosciences, Office of Basic Energy Sciences, US Department of Energy under contract DE-AC05-00OR22725, Oak Ridge National Laboratory, managed and operated by UT-Battelle, LLC. Sincere thanks go to B. Dutrow and an anonymous reviewer whose comments have greatly helped clarify the paper.

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