Structure of the Afar and Tanzania plumes based on the regional tomography using ISC data

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Establishment of the correlation between deep dynamics and processes observed at the daytime surface is an important fundamental problem of modern geodynamics. The study of mantle plumes, which are responsible for volcanic processes and riftogenesis in different parts of the Earth, occupies a special place in this problem. The system of rift depressions in East Africa and the Afar triple junction is the most striking example of the influence of mantle processes on the near-surface tectonic activity. The correlation between mantle dynamics and riftogenesis in this region has attracted the attention of many scholars around the world (see, for example, [1]). Quantitative estimates of pull-apart forces in the lithosphere induced by an ascending plume are estimated in [2]. These works and a multitude of other observations demonstrate that rifting in East Africa is caused precisely by mantle processes. The Afar triple junction (ATJ) is a transition case from continental rifting to oceanic spreading (Fig. 1). Three branches of divergence of the lithosphere located at almost equal angles (120 ° ) with respect to each other are observed around the ATJ. Two branches (the Red Sea and the Gulf of Aden) are incipient oceans with prominent spreading zones. The third branch (the Ethiopian Rift) is the beginning of a large system of depressions extended along the African continent first to the southwest and then to the south. The total length of the East African Rift is more than 2500 km. At a distance of approximately 700 km from the ATJ, the rifting is attenuated and then resumes again along two branches around the Tanzania Craton (Western and Eastern rifts). The Eastern Rift is also called the Kenya Rift in the literature, while the Western Rift is called Tanganyika Rift (from the name of Lake Tanganyika). The riftogenesis along the entire length of the