Structure Under the Bushveld Complex, South Africa from Receiver Functions

Abstract:

The Bushveld Igneous Complex (BIC) is the largest layered mafic intrusion on Earth and formed within Transvaal Basin in South Africa. The hypothesis that the limbs of the Rustenburg layer of the BIC are connected at depth is tested using teleseimic events of Mw > 5.5 to provide data under a seismic station (receiver) in the western limb of the BIC. Receiver functions have been computed from the data in order to image the layering under the Bushveld Complex. The receiver functions show discrete arrivals from the mafic layers, the Transvaal sediments under the BIC, and the Mohorovicic discontinuity at the base of the crust.. An interactive forward modeling method has been used to model the receiver functions in order to estimate the thickness of the BIC and the crust. Results show a BIC that is about 5-8 km thick and a Moho at ~40 km depth.