Abstract
We report new PKS, SKS, and SKKS splitting measurements for 88 seismic stations in Namibia, Botswana, South Africa, and Mozambique. When combined with measurements from previous studies, the ensemble of measurements shows a fairly uniform NNE to NE (∼41° on average) fast-polarization direction (ϕ) and delay time (δt) (∼0.7 s on average) across the entire southern African subcontinent. It is difficult to attribute the NNE-NE ϕ direction to just one source of anisotropy either within the lithospheric or sublithospheric mantle. We instead propose the observed anisotropy pattern could result from a combination of several sources that together give rise to a pervasive NNE-NE ϕ direction; (a) fossil anisotropy in the lithospheric mantle resulting from the Neoproterozoic collision of the Congo and Kalahari cratons to form the Damara Belt, (b) movement of the African plate over the asthenosphere, and (c) flow in the upper mantle induced by the African Superplume. In addition, a contribution from anisotropy in the lowermost mantle in the vicinity of the African large low shear velocity province cannot be ruled out.
Original language | English |
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Article number | e2023EA003469 |
Journal | Earth and Space Science |
Volume | 11 |
Issue number | 5 |
DOIs | |
Publication status | Published - May 2024 |
Bibliographical note
Publisher Copyright:© 2024. The Author(s).
Funding
Funders | Funder number |
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Council for Geoscience | |
Nederlandse Organisatie voor Wetenschappelijk Onderzoek | |
Namibia Geological Survey | |
National Research Foundation | |
National Science Foundation | 0824781, 0440032, 0530062, 1634108, 1128936 |
National Science Foundation |