Southern Africa crustal anisotropy reveals coupled crust-mantle evolution for over 2 billion years

The long-term stability of Precambrian continental lithosphere depends on the rheology of the lithospheric mantle as well as the coupling between crust and mantle lithosphere, which may be inferred by seismic anisotropy. Anisotropy has never been detected in cratonic crust. Anisotropy in southern Af...

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Bibliographic Details
Published in:Nature communications 2019-11, Vol.10 (1), p.5445-10, Article 5445
Main Authors: Thybo, H., Youssof, M., Artemieva, I. M.
Format: Article
Language:English
Subjects:
704/2151
704/2151/2809
704/2151/508
Anisotropy
Asthenosphere
Axes (reference lines)
Cratons
Evolution
Function analysis
Humanities and Social Sciences
Lithosphere
Magma
Mantle
multidisciplinary
Orogeny
Precambrian
Rheological properties
Rheology
Rock intrusions
Science
Science (multidisciplinary)
Seismic stability
Seismology
Splitting
Tectonics
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Summary:The long-term stability of Precambrian continental lithosphere depends on the rheology of the lithospheric mantle as well as the coupling between crust and mantle lithosphere, which may be inferred by seismic anisotropy. Anisotropy has never been detected in cratonic crust. Anisotropy in southern Africa, detected by the seismological SKS-splitting method, usually is attributed to the mantle due to asthenospheric flow or frozen-in features of the lithosphere. However, SKS-splitting cannot distinguish between anisotropy in the crust and the mantle. We observe strong seismic anisotropy in the crust of southern African cratons by Receiver Function analysis. Fast axes are uniform within tectonic units and parallel to SKS axes, orogenic strike in the Limpopo and Cape fold belts, and the strike of major dyke swarms. Parallel fast axes in the crust and mantle indicate coupled crust-mantle evolution for more than 2 billion years with implications for strong rheology of the lithosphere. The long-term stability of Precambrian continental lithosphere depends on the rheology of the lithospheric mantle as well as the coupling between crust and mantle lithosphere. Here, the authors study crustal seismic anisotropy to reveal that the crust and mantle lithosphere of southern Africa have been coupled since cratonisation, over 2 billion years ago.
ISSN:2041-1723
2041-1723
DOI:10.1038/s41467-019-13267-2