Collaborative Research: Experimental Determination of Trace Element Distributions between Melts and Mantle Phases at P, T and X Relevant to MORB Genesis

建议项目为在温度、压力和成分接近洋中脊部分熔融和洋中脊玄武岩（MORB）成因时存在的地幔相和熔体之间的耦合相平衡和微量元素分配的研究提供持续三年的资助。这项工作将建立在先前的结果的基础上，这些结果确定了在1.2到3.4 Gpa之间压力下橄榄岩地幔成分的矿物-熔融分配。用离子探针测定稀土元素（REE）、Hf、Zr、Nb、U、Th和Ba的晶液分配系数。将准备尽可能接近橄榄岩固体的分析电荷，以最接近部分地幔熔融的条件。在这项工作中，将研究在高达5.0 Gpa的压力下形成的橄榄岩实验电荷，包括在较低压力下的新研究。辉石岩电荷代表1.0-3.0 Gpa的压力也将被分析，形成关键的数据集，将允许测试模型假设石榴石辉石岩（或榴辉岩）在MORB和羽流融化的来源。贫橄榄岩（辉锌矿）电荷也将进行分析。这些新数据将被纳入新的地幔熔融综合模型，该模型将综合主微量元素组成

Recommended project is for three years of continued funding of research on coupled phase equilibria and trace element partitioning between mantle phases and melt at temperatures, pressures and compositions which closely approximate those which exist under mid-ocean ridges during partial mantle melting and mid-ocean ridge basalt (MORB) genesis. This work will build upon previous results that determined mineral-melt partitioning at for lherzolite mantle compositions at pressures between 1.2 and 3.4 Gpa. Crystal liquid partition coefficients will be determined for the rare earth elements (REE), Hf, Zr, Nb, U, Th, and Ba using an ion microprobe. Analytical charges will be prepared that are as close as possible to the peridotite solidus to most closely approximate conditions of partial mantle melting. In this work peridotite experimental charges formed at pressures up to 5.0 Gpa will be examined, including new studies at lower pressures. Pyroxenite charges representing pressures of 1.0-3.0 Gpa will also be analyzed, to form critical datasets that will allow the testing of models hypothesizing garnet pyroxenite (or eclogite) in the source of both MORB and plume melts. Depleted peridotite (harzburgite) charges will also be analyzed. These new data will be incorporated into new integrated models of mantle melting that integrate both major and trace element compositions.***