The tectonic generation of the Limpopo Mobile Belt, and a definition of its western extremity

Abstract

Abstract A new mechanism is suggested for the generation of the interference fold pattern which characterizes the Limpopo Mobile Belt. The mechanism is directly related to shear movement along the Tuli-Sabi Shear Zone, renamed the Tuli-Sabi Straightening Zone. The mobile belt is regarded as a taphrogenic lineament (McConnell, 1974) and its generation is compatible with the tectonic environment active in Proterozoic times according to Sutton and Watson (1974). Field evidence shows that the Tuli-Sabi Straightening Zone dies out in Botswana at Moshakabela, and it is reasoned that the mobile belt as a whole also disappears in this vicinity. It does not extend into central and western Botswana beneath the Karroo and Kalahari cover. Detailed examination of ERTS-1 imagery of northeastern Botswana strengthens these deductions. The Tuli-Sabi Straightening Zone and the characteristic fold patterns of the mobile belt can be seen quite clearly on the satellite imagery. Furthermore, the Tuli-Sabi Straightening Zone appears to be displaced southwards at the international boundary between Botswana and Rhodesia. The existence of a fold belt trending about N150° superimposed on the Limpopo Mobile Belt in the west of the area is postulated which is not the Shashe Mobile Belt (Crockett, 1967).