Evolution of the East African and Related Orogens, and the Assembly of Gondwana
Neoproterozoic closure of the Mozambique Ocean collapsed an accretionary collage of arc and microcontinental terranes and sutured East and West Gondwana along the length of the East African Orogen. This special issue of Precambrian Research brings together articles on aspects of the East African Orogen’s tectonic history to provide a better understanding of this ancient mountain belt and its relationships to the evolution of crust, climate, and life at the end of Precambrian time. The formation of Gondwana at the end of the Precambrian and the dawn of the Phanerozoic represents one of the most fundamental problems being studied in Earth Sciences today. It links many different fields, and there are currently numerous and rapid changes in our understanding of events related to the assembly of Gondwana. One of the most fundamental and most poorly understood aspects of the formation of Gondwana is the timing and geometry of closure of the oceanic basins which separated the continental fragments that amassed to form the Late Neoproterozoic supercontinent. It appears that the final collision between East and West Gondwana most likely followed the closure of the Mozambique Ocean, forming the East African Orogen. The East African Orogen encompasses the Arabian–Nubian Shield in the north and the Mozambique Belt in the south. These and several other orogenic belts are commonly referred to as Pan-African belts, recognizing that many distinct belts in Africa and other continents experienced deformation, metamorphism, and magmatic activity spanning the period of 800–450 Ma. Pan-African tectonothermal activity in the Mozambique Belt was broadly contemporaneous with magmatism, metamorphism and deformation in the Arabian–Nubian Shield. The difference in lithology and metamorphic grade between the two belts has been attributed to the difference in the level of exposure, with the Mozambican rocks interpreted as lower crustal equivalents of the juvenile rocks in the Arabian–Nubian Shield. Recent geochronologic data indicate the presence of two major Pan-African tectonic events in East Africa. The East African Orogeny (800–650 Ma; Stern, 1994) represents a distinct series of events within the Pan-African of central Gondwana, responsible for the assembly of greater Gondwana. Collectively, paleomagnetic and age data indicate that another later event at 550 Ma (Kuunga Orogeny) may represent the final suturing of the Australian and Antarctic segments of the Gondwana continent (Meert and van der Voo, 1996).
T. M. Kusky et al., "Evolution of the East African and Related Orogens, and the Assembly of Gondwana," Precambrian Research, vol. 123, no. 2-4, pp. 81-85, Elsevier, Jun 2003.
The definitive version is available at http://dx.doi.org/10.1016/S0301-9268(03)00062-7
Geosciences and Geological and Petroleum Engineering
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