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Evidence for a chemical-thermal structure at base of mantle from sharp lateral P-wave variations beneath Central America.

ABSTRACT: Compressional waves that sample the lowermost mantle west of Central America show a rapid change in travel times of up to 4 s over a sampling distance of 300 km and a change in waveforms. The differential travel times of the PKP waves (which traverse Earth's core) correlate remarkably well with predictions for S-wave tomography. Our modeling suggests a sharp transition in the lowermost mantle from a broad slow region to a broad fast region with a narrow zone of slowest anomaly next to the boundary beneath the Cocos Plate and the Caribbean Plate. The structure may be the result of ponding of ancient subducted Farallon slabs situated near the edge of a thermal and chemical upwelling.

SUBMITTER: Sun X

PROVIDER: S-EPMC1765446 | biostudies-literature | 2007 Jan

REPOSITORIES: biostudies-literature

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Evidence for a chemical-thermal structure at base of mantle from sharp lateral P-wave variations beneath Central America.

Sun Xinlei X Song Xiaodong X Zheng Sihua S Helmberger Don V DV

Proceedings of the National Academy of Sciences of the United States of America 20061220 1

Compressional waves that sample the lowermost mantle west of Central America show a rapid change in travel times of up to 4 s over a sampling distance of 300 km and a change in waveforms. The differential travel times of the PKP waves (which traverse Earth's core) correlate remarkably well with predictions for S-wave tomography. Our modeling suggests a sharp transition in the lowermost mantle from a broad slow region to a broad fast region with a narrow zone of slowest anomaly next to the bounda ...[more]

PMID: 17182740

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