Density structure of Earth's lowermost mantle from Stoneley mode splitting observations
Open access
Datum
2017-05-15Typ
- Journal Article
Abstract
Advances in our understanding of Earth’s thermal evolution and the style of mantle convection rely on robust seismological constraints on lateral variations of density. The large-low-shear-wave velocity provinces (LLSVPs) atop the core–mantle boundary beneath Africa and the Pacific are the largest structures in the lower mantle, and hence severely affect the convective flow. Here, we show that anomalous splitting of Stoneley modes, a unique class of free oscillations that are perturbed primarily by velocity and density variations at the core–mantle boundary, is explained best when the overall density of the LLSVPs is lower than the surrounding mantle. The resolved density variations can be explained by the presence of post-perovskite, chemical heterogeneity or a combination of the two. Although we cannot rule out the presence of a ∼100-km-thick denser-than-average basal structure, our results support the hypothesis that LLSVPs signify large-scale mantle upwelling in two antipodal regions of the mantle. Mehr anzeigen
Persistenter Link
https://doi.org/10.3929/ethz-b-000191294Publikationsstatus
publishedExterne Links
Zeitschrift / Serie
Nature CommunicationsBand
Seiten / Artikelnummer
Verlag
Nature