Seismic Evidence for a Hot Mantle Transition Zone Beneath the Indian Ocean Geoid Low

Abstract

AbstractThe Indian Ocean Geoid Low (IOGL) is the most prominent geoid anomaly (−106 m) on the globe, whose origin remains elusive. In the present study, we investigate the mantle transition zone (MTZ) structure beneath the region using P receiver functions (PRFs), to examine its role in the genesis of this feature. Results from 3‐D time to depth migration of PRFs reveal a thin MTZ primarily due to an elevation of the 660 km discontinuity. This is suggestive of anomalously hot temperatures in the mid mantle beneath the IOGL region, possibly sourced from the African Large Low Shear Velocity Province (LLSVP). The combined effect of the hot (low‐density) material in the MTZ proposed in this study and the (high‐density) cold slab graves atop the core‐mantle boundary inferred from previous studies can possibly explain this geoid low.