Late Cenozoic reorganization of the Arabia‐Eurasia collision and the comparison of short‐term and long‐term deformation rates

Abstract

The Arabia‐Eurasia collision deforms an area of ∼3,000,000 km2 of continental crust, making it one of the largest regions of convergent deformation on Earth. There are now estimates for the active slip rates, total convergence and timing of collision‐related deformation of regions from western Turkey to eastern Iran. This paper shows that extrapolating the present day slip rates of many active fault systems for ∼3–7 million years accounts for their total displacement. This result means that the present kinematics of the Arabia‐Eurasia collision are unlikely be the same as at its start, which was probably in the early Miocene (16–23 Ma) or earlier. In some, but not all, active fault systems, short‐term (∼10 year) and long‐term (∼5 million year) average deformation rates are consistent. There is little active thickening across the Turkish‐Iranian plateau and, possibly, the interior of the Greater Caucasus. These are two areas where present shortening rates would need more than 7 million years to account for the total crustal thickening, and where there are structural and/or stratigraphic data for pre‐late Miocene deformation. We suggest that once thick crust (up to 60 km) built up in the Turkish‐Iranian plateau and the Greater Caucasus, convergence took place more easily by crustal shortening in less elevated regions, such as the Zagros Simple Folded Zone, the South Caspian region and foothills of the Greater Caucasus, or in other ways, such as westward transport of Turkey between the North and East Anatolian faults. The time and duration of this changeover are not known for certain and are likely be diachronous, although deformation started or intensified in many of the currently active fault systems at ∼5 ± 2 Ma.

Geodetic constraints on present‐day motion of the Arabian Plate: Implications for Red Sea and Gulf of Aden rifting

“…The GPS plate rates are equal to within observational uncertainties to plate tectonic estimates of Africa motion for at least the past 11 Ma and for Arabia for more than 22 Ma, near the time when Arabia separated from Nubia. reflect (i.e., ±10%) fault slip rates (10 3 -10 6 years) and geologic plate motions (10 7 years), and accordingly the longterm, geologic evolution of the Africa-Arabia-Eurasia zone of plate interaction [see also Allen et al, 2004;Reilinger et al, 2006]. Calais et al [2003] suggest that Nubia-Eurasia relative motion has slowed by about 1 mm/yr during the past 3 Ma based on comparison of updated NUVEL-1A, geologic estimates with geodetic estimates of Nubia-Eurasia plate motion.…”

“…Separation from Africa resulted in the formation of ocean spreading in the Red Sea and Gulf of Aden [Chu and Gordon, 1998;Cochran, 1981] and in 200-500 km of compression along a continental collision zone in eastern Turkey, the Zagros, and the Caucasus Mountains [e.g., Jolivet and Faccenna, 2000;McQuarrie et al, 2003]. This continental collision is a major driver of the active tectonics of the eastern Mediterranean region [e.g., Sengor et al, 1985Sengor et al, , 2003Allen et al, 2004] and the devastating earthquakes that have affected this area throughout recorded history [e.g., Ambraseys and Jackson, 1998]. Furthermore, the kinematics of the separation of Arabia from Africa, and the continuing continental collision with Eurasia, offer opportunities to evaluate the role of different forces in driving/resisting Arabia plate motion [McQuarrie et al, 2003;Bellahsen et al, 2003].…”

Neogene sediments and modern depositional environments of the Zagros foreland basin system

“…The Zagros Mountains and the foreland are currently seismically extremely active. Recent GPS measurements indicate that the Arabian plate continues to move northwards relative to the Iranian microplate at rates of 20 ± 5 mm yr −1 (Tatar et al 2002;Blanc et al 2003;Nilforoushan et al 2003;Allen, Jackson & Walker, 2004;Allen et al 2006;Vernant et al 2004;Rielinger et al 2006;Walpersdorf et al 2006).…”

Geodynamic evolution of Upper Cretaceous Zagros ophiolites: formation of oceanic lithosphere above a nascent subduction zone

“…Growth of the ZOB reflects the continuing subduction of the Arabian continental crust beneath Iran, which began 10-20 Ma (McQuarrie et al 2003). Several major tectonic events occurred across the ZOB during Late Cretaceous, Late Eocene and Early to Middle Miocene times (Robertson, 2000;Agard et al 2005) with reorganization at 5 ± 2 Ma (Allen, Jackson & Walker, 2004). Abundant ophiolites in the ZOB define the southern Eurasian fore-arc and mark the suture with Arabia, which continues to develop.…”