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

橄榄石、辉石、石榴石和硅质碱性铝液体之间矿物熔体微量元素分配的实验测定

• 批准号: 9805300
• 负责人: David Draper
• 金额: $ 6.05万
• 依托单位: University of Texas at Dallas
• 依托单位国家: 美国
• 项目类别: Continuing Grant
• 财政年份: 1998
• 资助国家: 美国
• 起止时间: 1998-08-01 至 2002-01-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=9805300&HistoricalAwards=false
• 关键词: Experimental; Determination; Mineral; Melt; Trace

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.

[805300]地幔交代作用是微量元素从一个地幔区域转移到另一个地幔区域的重要机制，可能涉及从硅酸盐或碳酸盐熔体到富含溶质的含水流体等多种介质。目前尚不清楚是哪些因素导致了所谓的隐蔽性交代作用，否则难以解释的微量元素或同位素特征是唯一的证据。最近的实验工作已经确定了一种可能的隐交代介质：高硅，铝，碱性液体，其成分类似于在世界各地的许多地幔包体中发现的所谓的极端成分玻璃。这些结果可以推断，这些玻璃代表了由预富集的地幔原岩部分熔融产生的液体，并且实际上可以通过上地幔迁移并运输元素。为了将这项工作扩展到对它们可能传递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。它将为这些液体如何运输微量元素提供更准确的信息，阐明液体成分对微量元素分配行为的作用，并改进分配数据的参数化，从而产生微量元素分配作为压力、温度、矿物和熔体成分的函数的预测关系。