Grain growth control of isotope exchange between rocks and fluids

Michihiko Nakamura, Hisayoshi Yurimoto, E. Bruce Watson

Research output: Contribution to journalArticlepeer-review

19 Citations (Scopus)

Abstract

Isotope exchange between fluid and rocks has been traditionally considered to be rate limited by two elementary processes: lattice diffusion in the matrix minerals and dissolution into the fluid followed by precipitation from it. In this study we show the results of high-pressure experiments on 18O-water infiltration into quartzite that point to a third, highly efficient process: grain growth accompanied by migration of the grain boundaries (GBs) that are isotopically enriched by GB diffusion and surface exchange. We predict on the basis of a mass-transfer mechanism discrimination diagram that this GB sweeping is the primary control on isotopic equilibration under hydrothermal conditions in various fine-grained rocks with low fluid fraction. Grain growth should be considered when interpreting and simulating isotope and chemical composition of rocks and fluids.

Original languageEnglish
Pages (from-to)829-832
Number of pages4
JournalGeology
Volume33
Issue number10
DOIs
Publication statusPublished - 2005 Oct

Keywords

  • Diffusion
  • Fluid flow
  • Grain boundary
  • Oxygen isotope
  • Quartzite

ASJC Scopus subject areas

  • Geology

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