Granulite Facies Metamorphism
Understanding the processes and magnitude of partial melting in crustal rocks is crucial for evaluating magmatic arc processes, the contribution of crustal melts to batholiths, and growth and evolution of continental crust. Lower crustal rocks may record the influx of magma from subcrustal depths and the local generation of magma from partial melting. My work in the lower crust of the Cretaceous Fiordland magmatic arc is focused on documenting the timing and conditions of diorite to monzodiorite magma intrusion into the lower crust and subsequent garnet granulite metamorphism. Results suggest that widespread garnet granulite occurred less than 5 m.y. after a high flux intrusive event in the lower crust (Stowell and others, Journal of Metamorphic Geology, 2014; Schwartz and others, Geosphere, in press). This work has been funded by the U.S. National Science Foundation Tectonics, the New Zealand Royal Society, and New Zealand GNS Science. Work in progress will establish the spatial extent of this relationship and focus on testing whether garnet granulite metamorphism resulted from high heat flow following lithospheric delamination.
