Nubia-Arabia-Eurasia plate motions and the dynamics of Mediterranean and Middle East tectonics

Abstract

SUMMARY We use geodetic and plate tectonic observations to constrain the tectonic evolution of the Nubia–Arabia–Eurasia plate system. Two phases of slowing of Nubia–Eurasia convergence, each of which resulted in an ∼50 per cent decrease in the rate of convergence, coincided with the initiation of Nubia–Arabia continental rifting along the Red Sea and Somalia–Arabia rifting along the Gulf of Aden at 24 ± 4 Ma, and the initiation of oceanic rifting along the full extent of the Gulf of Aden at 11 ± 2 Ma. In addition, both the northern and southern Red Sea (Nubia–Arabia plate boundary) underwent changes in the configuration of extension at 11 ± 2 Ma, including the transfer of extension from the Suez Rift to the Gulf of Aqaba/Dead Sea fault system in the north, and from the central Red Sea Basin (Bab al Mandab) to the Afar volcanic zone in the south. While Nubia–Eurasia convergence slowed, the rate of Arabia–Eurasia convergence remained constant within the resolution of our observations, and is indistinguishable from the present-day global positioning system rate. The timing of the initial slowing of Nubia–Eurasia convergence (24 ± 4 Ma) corresponds to the initiation of extensional tectonics in the Mediterranean Basin, and the second phase of slowing to changes in the character of Mediterranean extension reported at ∼11 Ma. These observations are consistent with the hypothesis that changes in Nubia–Eurasia convergence, and associated Nubia–Arabia divergence, are the fundamental cause of both Mediterranean and Middle East post-Late Oligocene tectonics. We speculate about the implications of these kinematic relationships for the dynamics of Nubia–Arabia–Eurasia plate interactions, and favour the interpretation that slowing of Nubia–Eurasia convergence, and the resulting tectonic changes in the Mediterranean Basin and Middle East, resulted from a decrease in slab pull from the Arabia-subducted lithosphere across the Nubia–Arabia, evolving plate boundary.