Five years of continuously recording GPS observations in the Kingdom of Saudi Arabia together with new continuous and survey‐mode GPS observations broadly distributed across the Arabian Peninsula provide the basis for substantially improved estimates of present‐day motion and internal deformation of the Arabian plate. We derive the following relative, geodetic Euler vectors (latitude (°N), longitude (°E), rate (°/Myr, counterclockwise)) for Arabia‐Nubia (31.7 ± 0.2, 24.6 ± 0.3, 0.37 ± 0.01), Arabia‐Somalia (22.0 ± 0.5, 26.2 ± 0.5, 0.40 ± 0.01), Arabia‐India (18.0 ± 3.8, 87.6 ± 3.3, 0.07 ± 0.01), Arabia‐Sinai (35.7 ± 0.8, 17.1 ± 5.0, 0.15 ± 0.04), and Arabia‐Eurasia (27.5 ± 0.1, 17.6 ± 0.3, 0.404 ± 0.004). We use these Euler vectors to estimate present‐day stability of the Arabian plate, the rate and direction of extension across the Red Sea and Gulf of Aden, and slip rates along the southern Dead Sea fault south of the Lebanon restraining bend (4.5–4.7 ± 0.2 mm/yr, left lateral; 0.8–1.1 ± 0.3 mm/yr extension) and the Owens fracture zone (3.2–2.5 ± 0.5 mm/yr, right lateral, increasing from north to south; 1–2 mm/yr extension). On a broad scale, the Arabian plate has no resolvable internal deformation (weighted root mean square of residual motions for Arabia equals 0.6 mm/yr), although there is marginally significant evidence for N‐S shortening in the Palmyride Mountains, Syria at ≤ 1.5 mm/yr. We show that present‐day Arabia plate motion with respect to Eurasia is consistent within uncertainties (i.e., ±10%) with plate tectonic estimates since the early Miocene when Arabia separated from Nubia. We estimate the time of Red Sea and Gulf of Aden rifting from present‐day Arabia motion, plate tectonic evidence for a 70% increase in Arabia‐Nubia relative motion at 13 Ma, and the width of the Red Sea and Gulf of Aden and find that rifting initiated roughly simultaneously (±2.2 Myr) along the strike of the Red Sea from the Gulf of Suez to the Afar Triple Junction, as well as along the West Gulf of Aden at 24 ± 2.2 Ma. Based on the present kinematics, we hypothesize that the negative buoyancy of the subducted ocean lithosphere beneath the Makran and the Zagros fold‐thrust belt is the principle driver of Arabia‐Eurasia convergence and that resisting forces associated with Arabia‐Eurasia continental collision have had little impact on plate motion.

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Abstract:We propose a two-stage tectonic evolution of SE Afar in Djibouti leading to the complex development of highly asymmetric conjugate margins. From c. 8.5 to c. 2 Ma, an early mafic crust developed, associated in the upper crust with synmagmatic growth faults dipping dominantly to the SW. After an erosional stage, a new detachment fault system developed from c. 2 Ma with an opposite sense of motion (i.e. to the NE), during an amagmatic extensional event. In the Asal area, break-up occurred after c. 0.8 Ma along the footwall of an active secondary detachment fault rooted at depth above the lithospheric necking zone. This evolution suggests that flipflop detachment tectonics is developed during extension at passive margins, in connection with the dynamics of the melting mantle and the associated magma plumbing of the crust.

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