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 language | English |
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Pages (from-to) | 829-832 |
Number of pages | 4 |
Journal | Geology |
Volume | 33 |
Issue number | 10 |
DOIs | |
Publication status | Published - 2005 Oct |
Keywords
- Diffusion
- Fluid flow
- Grain boundary
- Oxygen isotope
- Quartzite
ASJC Scopus subject areas
- Geology