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

资金将允许广泛的，系统的放射性，U系列和微量元素地球化学研究的弧火山对千岛弧。其目标是描述整个岛弧典型岛弧环境下的各种岩浆过程。放射性同位素的变化将被用来描述在弧长寿命的地壳/地幔源的差异，和微量金属的变化将跟踪更近的过程有关的熔化或流体的相互作用。铀系不平衡也将被用来追踪熔融过程中的流体参与（238 U过量），并对地幔中的熔体输送时间进行限制（226 Ra过量）。地幔楔的沉积物输入将从ODP岩芯中的放射性同位素、宇宙成因10 Be和主要/微量元素的测量中获得。这项工作将在千岛岛弧中检验以下假设：1）板片在火山前缘下方产生一种流体，来自沉积物和蚀变洋壳，在弧后下方变成沉积物熔体; 2）印度地幔软流层延伸到千岛和堪察加; 3）弧后熔岩代表与火山前缘下地幔相似的低程度地幔熔融，流体通量较小; 4）弧后熔岩对元素通量的影响不大，特别是对U-Th-Pb、Rb-Sr、Sm-Nd、Lu-Hf等同位素组成的亲子对的影响更小。研究生和本科生将得到支持。

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.