On the generation of isotopic disequilibrium during crustal anatexis of ancient metasedimentary and granitic rocks.

摘要

Partial melting of rocks may lead to the generation of melts in isotopic disequilibrium with their source rocks. To examine the amount of disequilibrium created during anatexis in the Sr, Nd, and Pb isotopic systems, a model was producing using results of partial melt experiments to constrain the breakdown of major minerals during melting. Experimentally derived mineral dissolution equations were employed to account for contributions from accessory phases. Based upon results from this study, partial melts, especially from ancient rocks, are likely to be in considerable disequilibrium. The behavior of important accessory minerals during anatexis appears to exert considerable control over the magnitude of disequilibrium. The results of this work may have important implications for models of mass transfer during magmatism and for reconstructing temperature-time scales during episodes of crustal heating.