Asymmetrical lithospheric necking of Red Sea rift

The Red Sea rift exhibits two distinct rifting styles: in the north, the rifting is magma-poor, the crust is hyperextended and the lithospheric necking is asymmetric, in the south, rifting rapidly localized atop a symmetric lithospheric necking. One of the long-standing questions is what drives such different lithospheric necking style? We ran 2D high-resolution thermomechanical numerical simulations of lithospheric rifting to address the northern and southern Red Sea extensional end members and validate the models’ deformation patterns by comparing them against 2D data-driven structural models. The modelling investigates (a) the effect of rotational extension by varying extension velocities along the Red Sea, and (b) the thermal structure of the southern Red Sea due to plume impingement, while the analysis of the outcomes focuses on the early rifting stage, which involves normal rifting and dike intrusion. We find that asymmetrical lithospheric necking in the central and northern Red Sea is potentially driven by the velocity boundary conditions and inherited structures, mainly the Sirhan rift. The decoupling between the upper portion of the lithosphere and the asymmetrical lithospheric necking, which plays an essential role in the observed deformation patterns in the Arabian margin, is likely controlled by the lower crustal rheology and thickness. Furthermore, we find that the Afar plume near the southern Red Sea, which introduced in our models in form of thermal anomaly, promotes rifting localization.