Geodynamics of the East African Rift System ∼30 Ma ago: A stress field model. (June 2018)

• Record Type: Journal Article
• Authors: Min, Ge; Hou, Guiting
• Is Part Of: Journal of geodynamics. Volume 117(2018)
• Page Start: 1
• Page End: 11
• Publication Date: 2018-06
• Subjects: East African Rift System -- Intra-continental ridge -- Numerical simulation -- Upwelling mantle plumes -- Mid-ocean ridge spreading; Geodynamics -- Periodicals; Earth movements -- Periodicals; Rock deformation -- Periodicals; Earth -- Internal structure -- Periodicals; 551.1
• DOI: 10.1016/j.jog.2018.02.004
• Languages: English
• ISSNs: 0264-3707

Abstract

Abstract: The East African Rift System (EARS) is thought to be an intra-continental ridge that meets the Red Sea and the Gulf of Aden at the Ethiopian Afar as the failed arm of the Afar triple junction. The geodynamics of EARS is still unclear even though several models have been proposed. One model proposes that the EARS developed in a local tensile stress field derived from far-field loads because of the pushing of oceanic ridges. Alternatively, some scientists suggest that the formation of the EARS can be explained by upwelling mantle plumes beneath the lithospheric weak zone (e.g., the Pan-African suture zone). In our study, a shell model is established to consider the Earth's spherical curvature, the lithospheric heterogeneity of the African continent, and the coupling between the mantle plumes and the mid-ocean ridge. The results are calculated via the finite element method using ANSYS software and fit the geological evidence well. To discuss the effects of the different rock mechanical parameters and the boundary conditions, four comparative models are established with different parameters or boundary conditions. Model I ignores the heterogeneity of the African continent, Model II ignores mid-ocean spreading, Model III ignores the upwelling mantle plumes, and Model IV ignores both the heterogeneity of the African continent and the upwelling mantle plumes. Compared to these models is the original model that shows the best-fit results; this model indicates that the coupling of the upwelling mantle plumes and the mid-ocean ridge spreading causes the initial lithospheric breakup in Afar and East Africa. The extension direction and the separation of the EARS around the Tanzanian craton are attributed to the heterogeneity of the East African basement.