Shear wave velocity structure of the lower crust in southern Africa: Evidence for compositional heterogeneity within Archaean and Proterozoic terrains
Article first published online: 15 DEC 2009
Copyright 2009 by the American Geophysical Union.
Journal of Geophysical Research: Solid Earth (1978–2012)
Volume 114, Issue B12, December 2009
How to Cite
2009), Shear wave velocity structure of the lower crust in southern Africa: Evidence for compositional heterogeneity within Archaean and Proterozoic terrains, J. Geophys. Res., 114, B12304, doi:10.1029/2008JB006217., , , , , and (
- Issue published online: 15 DEC 2009
- Article first published online: 15 DEC 2009
- Manuscript Accepted: 19 AUG 2009
- Manuscript Revised: 29 JUN 2009
- Manuscript Received: 18 NOV 2008
- lower crust;
- intermediate to felsic
 The nature of the lower crust across the southern African shield has been investigated by jointly inverting receiver functions and Rayleigh wave group velocities for 89 broadband seismic stations located in Botswana, South Africa and Zimbabwe. For large parts of both Archaean and Proterozoic terrains, the velocity models obtained from the inversions show shear wave velocities ≥4.0 km/s below ∼20–30 km depth, indicating a predominantly mafic lower crust. However, for much of the Kimberley terrain and adjacent parts of the Kheis Province and Witwatersrand terrain in South Africa, as well as for the western part of the Tokwe terrain in Zimbabwe, shear wave velocities of ≤3.9 km/s are found below ∼20–30 km depth, indicating an intermediate-to-felsic lower crust. The areas of intermediate-to-felsic lower crust in South Africa coincide with regions where Ventersdorp rocks have been preserved, suggesting that the more evolved composition of the lower crust may have resulted from crustal reworking and extension during the Ventersdorp tectonomagmatic event at c. 2.7 Ga.