Experimental Determination of Mineral-Melt Trace-Element Partitioning Between Olivine, Pyroxene, Garnet, and Silicic Alkaline, Aluminous Liquid

9805300DraperMantle交代作用是微量元素从一个地幔区域向另一个地幔区域迁移的重要机制，可能涉及从硅酸盐或碳酸盐熔体到富含溶质的含水流体的各种介质。目前尚不清楚是哪些因素造成了所谓的隐蔽交代作用，而唯一的证据就是难以解释的微量元素或同位素特征。最近的实验工作已经确定了一种可能的隐蔽交代因素：高硅质、含铝的碱性液体，其成分与世界上许多地幔包体中发现的所谓极端成分玻璃的成分相似。这些结果导致推断，这种玻璃是由预富集的地幔原岩部分熔化产生的液体，实际上可以通过上地幔和输送元素迁移。为了将这项工作扩展到对它们可能提供的微量元素特征的检查，这项研究将确定这些液体和地幔矿物之间的分配行为。它将提供有关这些液体如何传输微量元素的更准确的信息，阐明液体组成对微量元素分配行为的作用，并改进分配数据的参数，这些参数可以产生作为压力、温度以及矿物和熔体组成的函数的痕量元素分配的预测关系。

9805300DraperMantle metasomatism is an important mechanism by which trace elements are transported from one mantle region to another and likely involves agents ranging from silicate or carbonate melts to solute-rich hydrous fluids. It is not clear which agents are responsible for so-called cryptic metasomatism, for which otherwise difficult-to-explain trace element or isotopic features are the only evidence. Recent experimental work has identified a likely agent of cryptic metasomatism: highly silicic, aluminous, alkaline liquids with compositions like those of so-called extreme-composition glasses found in many mantle xenoliths worldwide. These results lead to the inference that such glasses represent liquids that were generated by partial melting of a pre-enriched mantle protolith, and could in fact migrate through the upper mantle and transport elements. To extend this work to an examination of the possible trace-element signatures they can impart, this study will determine partitioning behavior between these liquids and mantle minerals. It will provide more accurate information on how these liquids might transport trace elements, elucidate the role of liquid composition on trace element partitioning behavior, and refine parameterizations of partitioning data that can yield predictive relationships for trace element partitioning as functions of pressure, temperature, and mineral and melt compositions.