The Tristan-Gough Plume Source and Constraints on the Composition of Recycled Sediment

与地幔热柱有关的大洋岛玄武岩是有关地幔不均一性先驱物质的主要信息来源。地幔热柱来源通常被认为代表了回收的大洋岩石圈。沉积物是洋壳再循环的一个组成部分，尽管对地幔热柱来源中存在的再循环沉积物的严格限制仍然有限。特里斯坦-高夫羽流轨道是海底体积最大的羽流轨道之一。戈夫熔岩新的高精度微量元素数据显示，稀土元素Ce(Ce)的含量出现负异常，其大小与较高的87Sr/86Sr和较低的176Hf/177Hf同位素比值有关。负Ce异常的存在为地幔中的再循环沉积物提供了一个强有力和令人兴奋的新示踪剂。这项研究将详细描述特里斯坦-戈夫羽流源中再循环沉积物组分的地球化学特征。通过将循环沉积物组分的组成与海底沉积物进行比较，俯冲过程中的微量元素分馏将受到限制，并对循环进入深部地幔的沉积物的组成产生影响。广泛的影响这项研究的结果将发表在国际期刊上，并将引起研究地幔动力学的大范围科学家的兴趣和益处。该提案涉及与南非开普敦大学勒罗克斯教授的国际合作。UCT的一名理学硕士(MSc)学生将访问LDEO，并将接受目前UCT无法提供的分析方法的接触和培训。为该提案提供资金将有助于支持地球观测组织的分析设施，并有助于一名女地球科学家的职业发展。

Oceanic island basalts associated with mantle plumes are a primary source of information on the precursor materials of mantle heterogeneities. Mantle plume sources are commonly thought to represent recycled oceanic lithosphere. Sediment is an integral part of the oceanic crust recycling, though rigorous constraints on the presence of recycled sediment in mantle plume sources are still limited. The Tristan-Gough plume track is among the volumetrically most significant plume tracks on the ocean floor. New high precision trace element data on Gough lavas reveal negative anomalies in the concentration of the rare earth element cerium (Ce), whose magnitude correlates with higher 87Sr/86Sr and lower 176Hf/177Hf isotope ratios. The presence of a negative Ce-anomaly offers a robust and exciting new tracer for recycled sediment in the mantle. This study will characterize in detail the geochemical signature of the recycled sediment component in the Tristan-Gough plume source. By comparing the composition of the recycled sediment component with ocean floor sediments, the trace element fractionations during subduction will be constrained with implications for the composition of sediments recycled into the deep mantle in general.Broader impactsThe results of this study will be published in international journals and be of interest and benefit to a large cross-section of scientists studying mantle dynamics. The proposal involves an international collaboration with Prof. le Roex at the University of Cape Town, South Africa (UCT). A Master of Science (MSc) student from UCT will be visiting LDEO and will be exposed and trained in analytical methods currently not available at UCT. Funding of the proposal will help to support the analytical facilities at LDEO and contribute to the career development of a woman geoscientist.