Seismic anisotropy and discontinuities of the lithosphere-asthenosphere system beneath La Réunion and the southern Mascarene Plateau

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The overarching goal of the German-French experiment RHUM-RUM is to seismologically image a mantle plume – or its absence – under the hotspot of La Réunion, and to understand the results in terms of convective flow at all depth levels of the Earth’s mantle. The majority of the data will become available in late 2013, at which time data analyses of various kinds will start, directed by the additional RHUM-RUM project partners.The two main objectives of the current proposal involve detailed seismological studies of the lithosphere-asthenosphere system and its possible interaction with and modification by the proposed mantle plume beneath La Réunion using the complete network of RHUM-RUM (OBS and island) stations:• An investigation of seismic anisotropy in relation to plume-induced mantle flow using shear-wave-splitting analyses.• The mapping of upper-mantle discontinuities with a focus on the determination of crustal and lithospheric thickness variations using P and S receiver-function methods.Additional topics covered by this proposal include studies of local and regional intra-plate seismicity and the detection and analysis of plume-scattered seismic signals by RHUM-RUM land stations in Mauritius.Of further relevance are recent findings based on zircon dating and gravity data which may suggest that the island of Mauritius and parts of the Southern Mascarene Plateau overlie fragments of continental lithosphere, a microcontinent called Mauritia. Crustal thickness estimates using receiver functions from stations of the RHUM-RUM network, including 11 seismic land stations in Mauritius, as proposed here, are uniquely suited to shed light on the current controversial debate on the existence of Mauritia.