Plate kinematics of the circum Red Sea—a re-evaluation

Abstract

Abstract Instantaneous and finite kinematic models of plate motions in the Red Sea area were constructed based on a re-evaluation of the plate boundaries in the Afro-Arabian rift system. The kinematic analysis is a useful way to integrate data from all parts of the system in order to better define its overall history. The most important new aspect of the models is the treatment of the Dead Sea transform as a leaky, or transtensional, feature. The detailed structure of the transform allows accurate location of the Eulerian poles of its young (0–5 Ma) and total (0–25 Ma) motion at (32.8°N, .22.6°E) ±0.5° and (32.7°N, 19.8°E) ±2°, respectively. This constrains the Red Sea opening pole to (32.5°N, 24.0°E) ±2°; only such locations predict geometries of Suez rift opening compatible with its structure. The Gulf of Aden pole is relocated at (24.5°N ± 0.5 °, 26.0 °E ± 2 °), about 5° southeast of previously accepted positions. The small differences between pole positions proposed here and previously accepted ones create significant shifts in the motions on the various rifts which are essential in the construction of self-consistent kinematic models compatible with the known geologic constraints. The kinematic analysis shows that (1) about 30 km of displacement has occurred along the Dead Sea transform in post-Miocene time, 10–15 km less than hitherto accepted, and (2) the opening of the Red Sea and Gulf of Aden has been less than their widths. Diffuse stretching and intrusional expansion amounting to about 200 km of plate separation took place in these basins prior to the initiation of centralized seafloor spreading as characterized by lineated magnetic anomalies. This suggests that the thinned continental crust and block fault structures of a mature continental margin are developed largely in an early stage of ocean evolution. The diffuse extension phase in the Red Sea has lasted longer where plate separation has been slow, but the amount of total extension prior to seafloor spreading has generally been about 250%, irrespective of the rate of plate separation.