The Mozambique orogenic belt and its foreland in northeast Tanzania: a photogeologically-based study

Abstract

The tectonic relationships within a rather large part (130,000 sq. km) of the Mozambique orogenic belt in N.E. Tanzania were investigated by photogeological interpretation and ground control Within the granitoid foreland (part of the Tanganyika Shield) the Dodoman and Nyanzian Greenstone belts, and charnockitie granulites are recognized. These were intruded and replaced by the chelogenie Katarchaean granite. Within the orogenic belt pre-Mozambiquian gneisses (termed Parangan) are exposed at the western margin, and in the floor of the orogen. These were tectonically reworked and transformed into L-tectonites and flaggy gneisses in the main Mozambiquian tectonism (termed Kondoan): this took place by strong folding about south-easterly-plunging axes, the folds being characteristically reclined. It is observed that structures transverse to the regional trend are a feature of other orogenic fronts such as the Grenville and Caledonian. In Tanzania they are succeeded by flexure folds on nne axes (termed Bongan), which locally become the predominant structures, parallel to the regional trend. In the north they are overturned towards the foreland and over-ride it. The Mozambiquian tectonism deforms the margin of the Shield and may penetrate it for considerable distances, perhaps contributing to the deformation in the Greenstone belts.