Local mineral equilibria and P-T paths: Fundamental principles and applications to high-grade metamorphic terranes
Published:February 01, 2011
Leonid L. Perchuk, 2011. "Local mineral equilibria and P-T paths: Fundamental principles and applications to high-grade metamorphic terranes", Origin and Evolution of Precambrian High-Grade Gneiss Terranes, with Special Emphasis on the Limpopo Complex of Southern Africa, Dirk D. van Reenen, Jan D. Kramers, Stephen McCourt, Leonid L. Perchuk
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This paper is a review of fundamental principles and rules for reconstructing pressure-temperature (P-T) paths followed by crystalline rocks. The fundamental principles are (1) the Prigogine-Korzhinskii principle of local equilibrium, and (2) the phase correspondence principle for coexisting minerals (Perchuk, 1971, 1977). These principles have consequences (rules) that are particularly useful for the complex assemblages that occur in Precambrian high-grade terranes. The resulting methodology is the only rigorous means of unraveling the history of polymetamorphic rocks. To assure the accuracy of any thermobarometric methodology it is essential to consider geological structures, microstructural analysis, calculations of mineral modes in terms of temperature and pressure, fluid inclusion data, and numerical modeling of P-T paths. The sequence in which these different approaches are considered has important consequences for the accurate reconstruction of P-T paths for polymetamorphic high-grade rocks. Several examples of P-T path reconstructions for mono- and polymetamorphic granulite facies complexes are considered in detail.