RUI: Polybaric Partial Melting of Peridotite

地幔部分熔融形成玄武岩是地球上最重要的地球动力学过程之一。经过几十年的高压实验，在2.0 ~ 3.0 GPa压力范围内的橄榄岩部分熔融数据很少。为了提高我们对近固体地幔熔融的认识，我们将完成一项为期三年的研究，研究多种橄榄岩成分的2.0-3.0 GPa部分熔融系统。精心挑选的橄榄石、正辉石、斜辉石和尖晶石颗粒来自两个不同成分的地幔捕虏体，将以不同的比例混合，以产生不同体积成分的起始材料。这些相同的起始材料之前在1.0 GPa下进行了研究。实验将使用活塞缸装置，利用金刚石骨料和“微夹层”技术的组合来消除玻璃的淬火改性问题。这将有助于确定低熔体分数玻璃和残余结晶相组成，估计在一定压力范围内的固体温度，量化熔体生产率和地幔熔融反应的化学计量学。由此产生的多压块数据集将为中洋脊环境中导致玄武岩形成的过程以及多压块熔融和橄榄岩-熔体相互作用发生的其他构造机制提供约束条件。该项目的一个组成部分和更广泛的影响包括本科生的直接参与和在一个主要是本科生的机构完成一个实验岩石学实验室。使用实验和项目数据的教学活动将被开发并纳入地质学课程，从而在未来长期受益于更多的学生。

The formation of basalt by partial melting of the Earth's mantle is one of the most significant geodynamic processes on the planet. Despite decades of high-pressure experiments, few peridotite partial melting data in the 2.0-3.0 GPa pressure range exist. In order to enhance our knowledge of near-solidus mantle melting, a three-year study investigating the 2.0-3.0 GPa partial melting systematics of multiple peridotite compositions will be completed. Handpicked olivine, orthopyroxene, clinopyroxene, and spinel grains from two mantle xenoliths, of differing compositional fertility, will be mixed in varying proportions to create starting materials of varying bulk composition. These same starting materials were studied previously at 1.0 GPa. Experiments will be performed using the piston-cylinder apparatus utilizing a combination of the diamond aggregate and "micro-sandwich" techniques to eliminate the problem of quench modification of the glass. This will enable determination of low melt fraction glass and residual crystalline phase compositions, estimation of solidus temperatures over a range of pressures, and quantification of melt productivity and the stoichiometry of mantle melting reactions. The resulting polybaric dataset will provide constraints on the processes resulting in the formation of basalts in the mid-ocean ridge environment, as well as other tectonic regimes where polybaric melting and peridotite-melt interaction occur. An integral component and broader impact of the project includes the direct involvement of undergraduate research students and completion of an experimental petrology laboratory at a primarily undergraduate institution. Teaching activities using the laboratory and project data will be developed and incorporated into the geology curriculum, thus benefiting a larger population of students long into the future.