Collaborative Research: Geochemistry of Ultramafic Xenoliths From the Mantle Wedge of the Kamchatka Arc

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This is a study of mantle-derived rocks found as xenoliths in three subduction-related volcanoes located on the Kamchatka Peninsula in the Russian Far East. The rock types of interest in this study are harzburgites and dunites that have been chemically altered (metasomatized) by hydrous fluids or melts derived from the down-going subducted plate, which produced millimeter and centimeter-scale veins and mineralized zones of pyroxene and amphibole or phlogopite in the mantle. The objective of the study is to understand the nature of the metasomatic process and its relationship to magma genesis in Kamchatka and other subduction systems. The project involves the collection of diverse geochemical data, including several of the gas-phase and light-element isotope systems (3He/4He, 3He/CO2, 13C, 18O, D) as well as heavy-element isotope ratios (Sr, Nd, Pb and Hf) that play a key role in our understanding of subduction-metasomatic processes. Trace element analyses will be done by ICPMS on whole-rock and mineral solutions. These data will be augmented by high-precision, isotope-dilution measurements of some high field strength element (Ta, Nb, Zr and Hf) concentrations. Graduate and undergraduate students from the University of Rochester and the University of South Carolina will be involved in all aspects of the data collection and interpretation. This is a collaborative project, domestically, between the University of Rochester and the University of South Carolina and, internationally, with the Russian Institute of Volcanic Geology and Geochemistry, in Petropavlovsk, Kamchatka, Russia..