AfricaArray seismological studies of the structure and evolution of the African continent

Abstract

The AfricaArray programme seeks to build geoscience capacity and conduct research that supports development in Africa. This paper reports on investigations of the structure and evolution of the African continent that have been concluded since the review presented at the 2009 SAGA Conference. The AfricaArray observatory network has been expanded from 33 to 49 stations, and 25 continuous GPS and 22 meteorological stations have been installed. A temporary seismic array has been deployed in Mozambique and Madagascar. Brandt and Mulibo elucidated the relationship between the African Superplume, Superswell and the East African Rift System by studying the seismic velocity structure of the mantle. Kgaswane jointly inverted P-wave receiver functions (PRFs) and surface waves, and found that the Kalahari Craton lower crust is largely mafic, except for a few terrains such as the Kimberley. Kgaswane also produced evidence that supports a link between the eastern and western lobes of the Bushveld Complex. Mangongolo used surface wave tomography to define the south-western boundary of the Congo Craton. El Tahir used PRFs to investigate the crustal structure of the Khartoum Basin. Tugume determined the Moho depths and Poisson’s ratios of the Precambrian crust in East Africa. Manzi reprocessed 3D reflection seismic data covering part of the Witwatersrand goldfields using seismic attribute analysis methods, and has provided new constraints on the evolution of the Basin during the Neoarchean. Loots interpreted a 105 km 2D seismic reflection profile immediately to the north of the Cape Fold Belt, imaging the Karoo and Cape Supergroup rocks and the seismic fabric of the basement. A zone of strong reflectors was found beneath the Beattie Magnetic Anomaly.