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

与地幔柱相关的大洋岛屿玄武岩是研究地幔非均质前体物质的主要资料来源。地幔柱源通常被认为代表了海洋岩石圈的循环。沉积物是海洋地壳再循环的一个组成部分，尽管对地幔柱源中存在再循环沉积物的严格限制仍然有限。特里斯坦-高夫羽流轨迹是海底体积上最重要的羽流轨迹之一。新的高精度微量元素数据揭示了稀土元素铈（Ce）浓度的负异常，其量级与较高的87Sr/86Sr和较低的176Hf/177Hf同位素比值相关。负ce异常的存在为地幔中再循环沉积物提供了强有力的、令人兴奋的新示踪剂。本研究将详细表征特里斯坦-戈夫羽流源区再循环沉积物组分的地球化学特征。通过与海底沉积物的再循环组分的比较，将限制俯冲过程中微量元素的分馏，从而对一般深部地幔再循环沉积物的组成产生影响。更广泛的影响这项研究的结果将发表在国际期刊上，并对研究地幔动力学的广大科学家感兴趣和有益。该提案涉及与南非开普敦大学（UCT）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，并将接触和培训UCT目前没有的分析方法。这项建议的经费将有助于支持LDEO的分析设施，并有助于女性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.