Partial melting of preexisting materials of the continental crust (anatexis) is an important process leading to long-term crustal differentiation and to the generation and evolution of evolved magmas in a number of important tectonic settings. Various isotope systems are commonly used as tracers of anatectic processes and source compositions, but the success of this approach depends on an assessment of equilibrium during partial melting in the continental crust. However, recent experimental and field investigations suggest that the assumption of isotopic equilibrium may not be valid for anatectic melts generated in some crustal environments. The objective of this project is to contribute to our understanding of the isotope systematics of Sr during dehydration melting of muscovite, biotite, and hornblende-bearing crustal assemblages. The Sr isotopic compositions of experimental partial melts segregated from their source using diamond aggregates will be measured by thermal ionization mass spectrometry. This technique provides a unique opportunity to investigate (1) the isotopic evolution of anatectic melts as a function of reaction progress and mineral stabilities and (2) mechanisms and time scales of melt-source equilibration during the generation and segregation of crustal melts.
