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

建议的项目是继续资助三年的研究，研究地幔相和熔体之间的耦合相平衡和微量元素分配，其温度、压力和成分非常接近部分地幔熔融和大洋中脊玄武岩(MORB)成因期间洋脊下存在的那些物质。这项工作将建立在以前的结果的基础上，这些结果确定了二辉橄榄岩地幔成分在1.2至3.4 Gpa压力下的矿物熔体分配。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相线的分析电荷，以最接近地幔部分熔融的条件。在这项工作中，将检查在压力高达5.0 Gpa时形成的橄榄岩实验电荷，包括在较低压力下的新研究。还将分析代表1.0-3.0 Gpa压力的辉石岩电荷，以形成关键数据集，以便对假设石榴石辉石岩(或榴辉岩)在MORB和羽流熔体来源中的模型进行测试。枯竭的橄榄岩(方辉橄榄岩)电荷也将被分析。这些新数据将被纳入新的地幔熔融综合模型，该模型综合了主要元素和微量元素的成分。

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.***