Seismic anisotropy in eastern Africa, mantle flow, and the African superplume

New estimates of seismic anisotropy from shear wave splitting measurements in eastern Africa reveal a pattern of seismic anisotropy dominated by a NE alignment of fast polarization directions with local changes around the thick Archean lithosphere of the Tanzania craton. The overall pattern is consi...

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Bibliographic Details
Published inGeophysical research letters Vol. 40; no. 8; pp. 1500 - 1505
Main Authors Bagley, Brian, Nyblade, Andrew A.
Format Journal Article
LanguageEnglish
Published Washington Blackwell Publishing Ltd 28.04.2013
John Wiley & Sons, Inc
Subjects
african superplume
Anisotropy
Cratons
Deformation
Earth mantle
Earth surface
Fossils
Joints
Lithosphere
Lower mantle
Magnesium composites
Mantle
Plate motion
Plate tectonics
Plateaus
Polarization
Seismology
shear wave splitting
Splitting
Tectonics
Uplift
Volcanic activity
Volcanism
Tanzania
Africa
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Summary:New estimates of seismic anisotropy from shear wave splitting measurements in eastern Africa reveal a pattern of seismic anisotropy dominated by a NE alignment of fast polarization directions with local changes around the thick Archean lithosphere of the Tanzania craton. The overall pattern is consistent with mantle flow from the African superplume but not with absolute plate motion, a plume head, or fossil anisotropy in the lithosphere. In combination with tomographic images of the African superplume, this finding suggests that plateau uplift, volcanism, and continental breakup along the Afro‐Arabian rift system is strongly influenced by flow from the lower mantle and indicates a connection between lower mantle processes and the tectonic deformation of the Earth's surface. Key Points The African superplume can explain all of the fast polarization directions Results indicate a connection between the lower mantle and tectonic deformation
Bibliography:ArticleID:GRL50315
Misfit grids of stacked results for each station. The double contour line indicates the 95% confidence area. The back-azimuth plot to the left of each misfit grid shows the azimuthal distribution of the events used for each station.Variation in delay time as a function of initial polarization azimuth for each station.Variation in fast direction as a function of initial polarization azimuth for each station.Averaged splitting results in the Proterozoic orogenic belts and the Tanzania craton. Groups are defined by different colors, the numbers in the white boxes are fast direction (left) and delay time (right).Stacked splitting results for networks ZP and AF.Events and phases for splitting analysisIndividual splitting results by station.Apparent splitting results for SKS and SKKS from the same event-station pair.Supporting Information
National Science Foundation - No. OISE-0530062; No. EAR-0440032; No. EAR-0824781
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ISSN:0094-8276
1944-8007
DOI:10.1002/grl.50315