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The root to the Galápagos mantle plume on the core-mantle boundary

Authors :
Cottaar, Sanne
Martin, Carl
Li, Zhi
Parai, Rita
Cottaar, Sanne [0000-0003-0493-6570]
Martin, Carl [0000-0002-2882-543X]
Li, Zhi [0000-0001-5657-655X]
Parai, Rita [0000-0002-9754-7349]
Apollo - University of Cambridge Repository
Source :
Seismica. 1
Publication Year :
2022
Publisher :
McGill University Library and Archives, 2022.

Abstract

Ultra-low velocity zones (ULVZs) are thin anomalous patches on the boundary between the Earth's core and mantle, revealed by their effects on the seismic waves that propagate through them. Here we map a broad ULVZ near the Galápagos hotspot using shear-diffracted waves. Forward modelling assuming a cylindrical shape shows the patch is ~600 km wide, ~20 km high, and its shear velocities are ~25% reduced. The ULVZ is comparable to other broad ULVZs mapped on the core-mantle boundary near Hawaii, Iceland, and Samoa. Strikingly, all four hotspots where the mantle plume appears rooted by these ‘mega-ULVZs’, show similar anomalous isotopic signatures in He, Ne, and W in their ocean island basalts. This correlation suggests mega-ULVZs might be primordial or caused by interaction with the core, and some material from ULVZs is entrained within the plume. For the Galápagos, the connection implies the plume is offset to the west towards the base of the mantle.

Details

ISSN :
28169387
Volume :
1
Database :
OpenAIRE
Journal :
Seismica
Accession number :
edsair.doi.dedup.....505b38b457b6918c7f2d7a79e23e6ae8
Full Text :
https://doi.org/10.26443/seismica.v1i1.197