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Nat Commun. 2019 Nov 29;10(1):5445. doi: 10.1038/s41467-019-13267-2.

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

Author information

1
School of Earth Sciences, China University of Geosciences, Wuhan, China. thybo@geo.uio.no.
2
Eurasia Institute of Earth Sciences, Istanbul Technical University, Istanbul, Turkey. thybo@geo.uio.no.
3
Centre for Earth Evolution and Dynamics (CEED), University of Oslo, Oslo, Norway. thybo@geo.uio.no.
4
King Abdullah University of Science and Technology (KAUST), Thuwal, Saudi Arabia.
5
Stanford University, Palo Alto, CA, USA.

Abstract

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.

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