Rift and plume: a discussion on active and passive rifting mechanisms in the Afro-Arabian rift based on synthesis of geophysical data

The causal relationship between the activity of mantle plumes and continental break-up is still elusive. The Afro-Arabian rift system offers an opportunity to examine these relationship, in which an ongoing continental break-up intersects a large Cenozoic plume related flood basalt series. In the Afar region, the Gulf of Aden, the Red-Sea and the Main Ethiopian Rift form an R-R-R triple junction and separate the Ethiopian and Yemen Traps by ~600 km. We provide an up-to-date synthesis of the available geophysical and geological data from this region. We map the rift architecture in the intersection region of the rifts and review the spatio-temporal constraints in the development of the different features of the plume‐rift system.

We infer two spatial constraints in the development of the rifts: (1) the connection of the Main Ethiopian Rift to the Gulf of Aden and to the Red Sea by its northeastward propagation; (2) the abandonment of an early tectonic connection between the Red Sea and the Gulf of Aden. Additionally, chronological evidence suggests that regional uplift and flood basalt eruptions sufficiently preceded rifting. By this, we infer a progressive development in which the onset of the triple junction marks a tectonic reorganization and was the last feature to develop, after all rift arms were thoroughly developed. We argue that the classical active and passive rifting mechanisms cannot simply explain the progressive development of the Afro-Arabian rift and propose a scenario of plume-induced plate rotation that includes an interaction between active and passive mechanisms. In this scenario, the arrival of the Afar plume provided a push-force that promoted the rotation of Arabia around a nearby pole, enabling rifting and ultimately the break-up of Arabia from Africa.