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.

authors

Sun X,Song X,Zheng S,Helmberger DV

doi

10.1073/pnas.0609143103

subject

Has Abstract

pub_date

2007-01-02 00:00:00

pages

26-30

issue

1

eissn

0027-8424

issn

1091-6490

pii

0609143103

journal_volume

104

pub_type

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