Presentation by Xiyuan Bao.
Deep Provenance of East Africa and Indian Ocean Hotspots through Tomography, Graph Theory, and Geochemical Cross-validation
Hotspot volcanism is conventionally attributed to vertical mantle plumes from deep mantle sources to the surface. However, recent seismic imaging reveals complex networks of plume-like anomalies, making surface-source mapping challenging due to possible non-uniqueness. We propose an objective, graph-theory-based framework that constructs an ensemble of plume paths using a high-resolution regional seismic tomographic model. Applied to eight East African and Indian Ocean hotspots, our method consistently identifies clustered source zones near the core–mantle boundary in different regional/global tomographic models, showing robust grouping of Afar, East Africa, and Comores, versus Reunion, versus Marion, Crozet, Kerguelen and Amsterdam-St Paul. Multivariate analysis with machine learning of the Sr-Nd-Pb isotope ratios of hotspot-related basalts reveals the same clustering. Hence, we infer the first deep mantle compositional zoning map in this region, delineating at least three distinct domains within the African Large Low Shear Velocity Province (LLSVP).
