Mantle plumes and associated flow beneath Arabia and East Africa

We investigate mantle plumes and associated flow beneath the lithosphere by imaging the three-dimensional S-velocity structure beneath Arabia and East Africa. This image shows elongated vertical and horizontal low-velocity anomalies down to at least mid mantle depths. This three-dimensional S-veloci...

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Bibliographic Details
Published in:Earth and planetary science letters 2011-02, Vol.302 (3), p.448-454
Main Authors: Chang, Sung-Joon, Van der Lee, Suzan
Format: Article
Language:English
Subjects:
Anomalies
Arabia
Channels
East Africa
Horizontal
Inversions
joint inversion
Mantle
mantle flow
mantle plume
Plumes
seismic tomography
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Summary:We investigate mantle plumes and associated flow beneath the lithosphere by imaging the three-dimensional S-velocity structure beneath Arabia and East Africa. This image shows elongated vertical and horizontal low-velocity anomalies down to at least mid mantle depths. This three-dimensional S-velocity model is obtained through the joint inversion of teleseismic S- and SKS-arrival times, regional S- and Rayleigh waveform fits, fundamental-mode Rayleigh-wave group velocities, and independent Moho constraints from receiver functions, reflection/refraction profiles, and gravity measurements. In the resolved parts of our S-velocity model we find that the Afar plume is distinctly separate from the Kenya plume, showing the Afar plume's origin in the lower mantle beneath southwestern Arabia. We identify another quasi-vertical low-velocity anomaly beneath Jordan and northern Arabia which extends into the lower mantle and may be related to volcanism in Jordan, northern Arabia, and possibly southern Turkey. Comparing locations of mantle plumes from the joint inversion with fast axes of shear-wave splitting, we confirm horizontal mantle flow radially away from Afar. Low-velocity channels in our model support southwestward flow beneath Ethiopia, eastward flow beneath the Gulf of Aden, but not northwestwards beneath the entire Red Sea. Instead, northward mantle flow from Afar appears to be channeled beneath Arabia. ► New evidence for the distinct two plumes beneath East Africa is obtained. ► Another plume beneath northern Arabia and Jordan is found. ► Horizontal mantle flow away from Afar seems to be the dominant cause of anisotropy. ► We find a northward-trending channel of low-velocity anomaly beneath Arabia.
ISSN:0012-821X
1385-013X
DOI:10.1016/j.epsl.2010.12.050