Margins: Experimental Investigation of Hydrous Peridotite Melting beneath Volcanic Arcs

0112013 Gaetani该项目的目标是（1）确定地幔橄榄岩通过俯冲洋壳岩石圈富H2O组分熔融形成的含水部分熔体的成分特征和液相线温度，以及（2）测量适合于模拟地幔楔中含水橄榄岩部分熔融期间微量元素分馏的矿物/熔体分配系数。 这些目标是通过实验确定（1）在2.0 - 3.0 GPa下与二辉橄榄岩矿物组合平衡的含水硅酸盐熔体的组成，（2）向橄榄岩中加入不同量的Na 2 O-K 2 O-H 2 O俯冲组分对部分熔融的影响，和（3）地幔矿物之间不相容微量元素的分配来实现的（单斜辉石，石榴石，角闪石）和含水的部分熔体在火山弧下的地幔适当的条件。这项实验研究的结果将提供必要的岩石学和地球化学数据，以了解H2O在生成弧岩浆中的作用，并确定物质的组成，从地幔转移到地壳的俯冲相关的岩浆过程。研究结果还将有助于为解释伊豆-小笠原-马里亚纳和中美洲俯冲系统中MARGINS焦点地点的样本提供一个框架。

0112013GaetaniThe objectives of this project are (1) to determine the compositional characteristics and liquidus temperatures of hydrous partial melts formed through fluxing of mantle peridotite by a H2O-rich component from the subducted oceanic lithosphere, and (2) to measure mineral/melt partition coefficients appropriate for modeling trace element fractionations during partial melting of hydrous peridotite in the mantle wedge. These goals are being achieved by determining experimentally (1) the compositions of hydrous silicate melts in equilibrium with a lherzolite mineral assemblage at 2.0 to 3.0 GPa, (2) the effect on partial melting of adding variable amounts of a Na2O-K2O-H2O subduction component to the peridotite, and (3) the partitioning of incompatible trace elements between mantle minerals (clinopyroxene, garnet, amphibole) and hydrous partial melts at conditions appropriate for the mantle beneath volcanic arcs. The results from this experimental study will provide petrologic and geochemical data necessary for understanding the role of H2O in generating arc magmas and determining the composition of material transferred from the mantle to the crust by subduction-related magmatic processes. The results will also help to provide a framework for interpreting samples from MARGINS Focus Sites in the Izu-Bonin-Mariana and Central American subduction systems.