Southern Africa crustal anisotropy reveals coupled crust-mantle evolution for over 2 billion years.
Online Publication Date2019-11-29
Print Publication Date2019-12
Permanent link to this recordhttp://hdl.handle.net/10754/660507
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AbstractThe 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.
CitationThybo, H., Youssof, M., & Artemieva, I. M. (2019). Southern Africa crustal anisotropy reveals coupled crust-mantle evolution for over 2 billion years. Nature Communications, 10(1). doi:10.1038/s41467-019-13267-2
SponsorsWe thank the IRIS/PASSCAL Data Management Centre for providing the SASE seismic data and the seismic codes used in this study. Discussions with Lev Vinnik improved the paper. This study was supported by grants FNU10-083081 to I.M.A. and FNU11-104254 to H.T. from the Danish Research Council. Partially supported by the MOST special funds for GPMR State Key Laboratory (GPMR2019010).
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