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

与地幔柱有关的洋岛玄武岩是研究地幔不均匀性前体物质的主要信息来源。地幔柱源通常被认为是再循环的大洋岩石圈。沉积物是洋壳再循环的一个组成部分，尽管对地幔柱源中再循环沉积物的存在的严格限制仍然有限。特里斯坦-高夫羽流轨迹是洋底体积最大的羽流轨迹之一。高夫熔岩的新的高精度微量元素数据显示，稀土元素铈（Ce）的浓度呈负异常，其幅度与较高的87 Sr/86 Sr和较低的176 Hf/177 Hf同位素比值相关。负Ce异常的存在提供了一个强大的和令人兴奋的新的示踪回收的沉积物在地幔。这项研究将详细描述特里斯坦-高夫羽流源中再循环沉积物成分的地球化学特征。通过比较海底沉积物和再循环沉积物成分的组成，俯冲过程中的微量元素分馏将受到限制，并对再循环进入深部地幔的沉积物成分产生影响。该提案涉及与南非开普敦大学的le Roex教授的国际合作。来自UCT的理学硕士（MSc）学生将访问LDEO，并将在UCT目前无法获得的分析方法中进行暴露和培训。对该提案的资助将有助于支持LDEO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.