History of the development of Permian to Cretaceous rifts in East Africa: a series of interpreted maps through time

East Africa represents the most rifted portion of crust on the planet, having been subjected to numerous phases of extension from Permian to Recent times. The first rifting phase commences in the Permian as the 'Karoo' set of narrow half-graben, many formed by lateral shear. Peak rifting appears to be of Middle Permian age for rifts south of Tanzania. In Kenya, Ethiopia and Somalia, this rift population merges into a set of rifts with peak rifting of earliest Triassic age. A further phase of rifting is seen in the Toarcian–Aalenian. Many of these overlie Permo-Triassic rifts but others are displaced towards what will become the continental margin. Three unrelated populations of Late Jurassic–Early Cretaceous rifts are observed, including those in Somalia, a series of pull-apart basins on the Davie Ridge and a poorly documented set in southern Mozambique. The Anza Rift, with peak rifting in the Late Cretaceous associated with the building of rift shoulders kilometres in height, is proposed here to be an isolated plume-derived rift. Evaluation of the petroleum potential associated with these rifts relies on an accurate assessment of each in terms of their age and affinity to well-documented systems.