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New seismic model of the upper mantle beneath Africa

Jeroen Ritsema and Hendrik-Jan van Heijst
New seismic model of the upper mantle beneath Africa
Geology (Boulder) (January 2000) 28 (1): 63-66

Abstract

We present a seismic model of the upper 400 km of the mantle beneath Africa and surrounding regions. This model is constructed by inverse modeling of fundamental mode Rayleigh wave phase velocities (40-200 s) for about 8000 propagation paths. Among the most pronounced anomalies are high shear velocity structures (as much as 6% higher than in the Preliminary Reference Earth model) beneath the West African, Congo, and Kalahari cratons that extend to about 250 km depth. These structures have near-vertical margins across which the shear velocity changes by as much as 6% over 500 km distance. Anomalous low shear velocities (3%-4% lower than in the Preliminary Reference Earth Model) structures are observed beneath the East African, Red Sea, and Gulf of Aden rifts, and beneath the northwestern Indian Ocean. These structures extend to a depth of at least 250 km. Our model cannot be reconciled with models that invoke a large number of plumes that have impinged on the base of the lithosphere, nor does our seismic model indicate that high-temperature, low-density material beneath the lithosphere is responsible for the uplift of southern Africa.


ISSN: 0091-7613
EISSN: 1943-2682
Coden: GLGYBA
Serial Title: Geology (Boulder)
Serial Volume: 28
Serial Issue: 1
Title: New seismic model of the upper mantle beneath Africa
Affiliation: California Institute of Technology, Seismological Laboratory, Pasadena, CA, United States
Pages: 63-66
Published: 200001
Text Language: English
Publisher: Geological Society of America (GSA), Boulder, CO, United States
References: 25
Accession Number: 2000-018579
Categories: Solid-earth geophysicsApplied geophysics
Document Type: Serial
Bibliographic Level: Analytic
Illustration Description: illus. incl. sketch maps
N10°30'00" - N15°00'00", E43°00'00" - E52°00'00"
Country of Publication: United States
Secondary Affiliation: GeoRef, Copyright 2018, American Geosciences Institute. Reference includes data supplied by the Geological Society of America, Boulder, CO, United States
Update Code: 200006
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