Seismic Imaging of the Bushveld Complex, South Africa

Abstract:

This study addresses the limited understanding of upper crustal structure beneath the Bushveld Complex, South Africa. Upper crustal structure and Moho depths are investigated using a joint inversion of P-wave receiver functions and Rayleigh wave group velocities with an aim to determine whether there is structural continuity in the subsurface between the western and eastern lobes (limbs) of the Bushveld Complex. Passive source seismic data from over forty broadband seismic stations are being used, including data from the 2015-2020 AfricaArray Bushveld network, the 1997-1998 South African Seismic Experiment, and permanent AfricaArray stations. The combination of these networks provides fairly uniform station coverage over most of the Bushveld Complex. Receiver functions are obtained from teleseismic earthquakes and Rayleigh wave group velocities are from an ambient noise tomography of southern Africa. Preliminary 1-D shear wave depth-velocity models for each station produced from the joint inversion show complicated upper crustal structure with high velocity zones indicative of the mafic/ultramafic layering present beneath a number of the stations across the interior of the complex, but not all of them.