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 impacts The 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.