Modelling isotopic responses to disequilibrium melting in granitic systems

Abstract

Granite petrogenesis is an important component of crustal growth and evolution; however, the isotope systems commonly applied to investigations of such processes (Sr, Nd, Pb and Hf) may behave in a more complex manner during partial melting and crystallization than is often assumed in petrogenetic models. Using a range of experimentally determined melting reactions and accessory mineral dissolution equations, the Sr-, Nd- and Hf-isotopic compositions of melt, source (protolith), and restite (residual source material including peritectic phases) have been calculated for a variety of hypothetical melting scenarios, in which the protoliths have acquired an isotopically heterogeneous mineral ass..