Kerguelen地幔柱不同时期玄武岩的水含量变化及其与地幔柱演化的关系

地幔柱模型通常被用来解释大火成岩省和洋岛玄武岩的形成，分别代表地幔柱不同演化阶段的熔融产物。由于水的存在显著影响地幔物质的物理和化学性质，因此地幔柱水含量的变化是影响其演化的重要因素之一。研究显示，从大火成岩省到洋岛火山链，同一地幔柱产生的玄武岩的微量元素和同位素组成存在一定的变化。但是，玄武岩水含量的变化并没有得到系统研究，水在地幔柱演化中的作用也因此尚不明确。Kerguelen地幔柱形成了从大火成岩省（包括Kerguelen海洋高原等）到洋岛玄武岩（分布在Ninetyeast Ridge玄武岩火山链和Kerguelen群岛等），持续时间超过120 Ma的玄武岩序列，是研究水与地幔柱演化的关系的天然实验室。本项目将研究不同时期玄武岩的初始水含量，了解地幔柱中水含量的变化；结合H-O同位素组成和其它地球化学特征，分析水的来源和造成这些变化的机制，最终探讨水含量变化与地幔柱演化的关系。

The mantle plume model is a widely accepted explanation for the formation of large igneous provinces (LIPs) and oceanic island basalts (OIBs), representing melting products at different evolutional stages of individual mantle plumes (heads vs. tails). The existence of water can significantly affect the physical and chemical properties of mantle materials; it is therefore expected that the water content change may have influenced the plume evolution. Although previous studies have shown that the trace element and isotope compositions in basalts display some variations between the LIPs and OIBs generated by the same mantle plume, no systematic study has been conducted on the variations in water content and the role of water in the evolution of mantle plume has not been clarified. The Kerguelen mantle plume caused magmatic activities in the past more than 120 Ma. It generated a LIP (the Kerguelen Oceanic Plateau as the main body), and OIBs distributing along the Ninetyeast Ridge and in the Kerguelen Archipelagoes. In this project, primary water contents of basalts from different periods will be obtained to figure out the temporal variations in water content in the Kerguelen plume. Combining with the H-O isotopic compositions and other geochemical data, we will evaluate the origin of water and the mechanism responsible for the water content change. Once these data are acquired, the link between the water content change and the plume evolution is expected to be revealed.