A new Moho map of the African continent from seismic, topographic, and tectonic data

Abstract

We use seismic surveys (853 stations and 79 seismic profiles) to compile a new continental Moho model of the African continent of which 90% is formed by the Precambrian crust. The result reveals considerable Moho depth variations, with values ranging from 14 to 20 km for the Afar Triple Junction and Turkana Lake to 46 km beneath the Rif Mountains, parts of the Ethiopian Plateaus, and the Namaqua-Natal Belt. A localized Moho deepening (∼44 km) is found beneath the western and eastern blocks of the Congo Craton, the central part of Victoria Lake, the Rehoboth Province, the eastern part of the Kaapvaal Craton, and the Irumide Belt. A shallow Moho depth is detected beneath wide areas in North, Central, and East Africa, particularly along the North Africa coast (24–30 km), the Mauritanian Belt (26–30 km), the West and Central African Rift System (30–32 km), the Benue Trough (24–28 km), and beneath the Rwenzori Mountains (26–30 km) and the southern part of Somali Plate (22–26 km). At many locations, a Moho relief is characterized by significant changes across different tectonic provinces; from the Afar Triple Junction, Turkana Depression, and the Somali Plate to the Main Ethiopian Rift, between the Rwenzori region, from the Gabon-Cameroon Shield to the Benue Trough, and from the western border of the West African Craton to the Mauritanian Belt. According to our estimates, an average Moho depth beneath the African continent is 36.1 km. Comparison of our result with selected global, continental, and regional Moho models shows large differences that locally even exceed ±15 km.