Collaborative Research: Variations of sedimentary input to magma genesis across the Kurile arc

Washington University, Saint Louis MO

Investigators

Abstract

Funds will allow an extensive, systematic radiogenic, U-series, and trace element geochemistry study of arc volcanism on the Kurile arc. The objective is to characterize various magmatic processes beneath a typical island arc setting across the entire arc. Radiogenic isotope variations would be used to characterize differences in long-lived crust/mantle sources across the arc, and trace metal variations will trace more recent processes related to melting or fluid interactions. Uranium-series disequilibria would also be used to trace fluid involvement during melting (238U excess) and to place constraints on melt transport times in the mantle (226Ra excess). Sediment inputs to the mantle wedge would be obtained from measurements of radiogenic isotopes, cosmogenic 10Be, and major/trace elements in ODP drill cores. The work will test the following hypotheses in the Kurile arc: 1) That the slab yields a fluid beneath the volcanic front, deriving from both sediments and altered oceanic crust, which changes to a sediment melt beneath the rear arc; 2) Indian mantle asthenosphere extends into the Kuriles and Kamchatka; 3) Rear-arc lavas represent lower degree melts of a mantle that is similar to that beneath the volcanic front, with lesser fluid fluxes; and 4) Rear-arc lavas have little effect on element fluxes, particularly on the parent-daughter pairs of the U-Th-Pb, Rb-Sr, Sm-Nd, Lu-Hf isotope systematics. Graduate and undergraduate students will be supported.