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- Reconstruction of Zagros evolution
| Figure (3. 1): Maps demonstrating the reconstruction of Neo-Tethys and the connection between the Red Sea's opening and the collision of Arabia and Eurasia (as indicated by the overlap of the shaded region). The long, gray-shaded bands show how much crust has been shortened in Eurasia (80 km) and on the Arabian plate (70 km). The passive margins (50 km) on the north and south sides of the Neo-Tethyan ocean basin are represented by narrower (inside) bands. Convergence rates are given at 32.70°N and 50.38°E (McQuarrie et al., 2003).
This spreading center produces earthquakes along its boundaries with the surrounding plates, such as those along its north-western margins that form the Zagros Mountains in Iran (Luo et al., 2016). The Zagros is one of the most seismically active intercontinental fold and thrust belts and a critical component of active tectonics (Karimiparidari et al., 2013). The closure of the Paleo-Tethys Ocean started in the Carboniferous region with the initiation of a subduction northward under Eurasia. The NE passive margin of the Arabian plate begins progressing under Iran’s center during the Upper Cretaceous. The Neo-Tethys is closed onto the continental crust (89.3±1.0 ± 83.5±0.7). At a rate of about 1.2 cm/year in an NNE direction, the Arabian plate is separating from Africa (Nubia) along the Red Sea (Berberian and King, 1981). Arabian plate wards to Iran blocks triggered the Zagros collision in the upper Oligocene and lower Miocene (Agard et al., 2005). Reconstruction of Zagros evolutionFrom the Paleozoic to the present, the evolution of the Arabian Plate with the Eurasian plate boundary has been described and illustrated. Plate tectonics in the Zagros Mountains during the Paleozoic Era During the late Precambrian and early Permian, the Persian platform widened. The Arabian and adjoining plates fused along the northeastern flank of the African plate in Gondwanaland. They resulted in a carbonization event on the Persian platform during the latest Precambrian. Some of the region's N-S trending structural features may have originated during Late Precambrian tectonic activity. During the late Precambrian, the platform was influenced by an extensional episode caused by continental rifting or a back-arc basin, creating intraplate depressions where significant evaporates were deposited (Husseini, 1989). Extensive carbonate deposition throughout the Cambrian suggests the possibility of a passive margin setting; still, thorough examinations have determined that the platform was an active margin during this time. From the Ordovician to the Middle Devonian and from the Mississippian to the Permian, the platform became a passive margin, and during the Late Devonian, it became an active margin (Golonka, 2000). Because the highest Precambrian and Permian strata have similar sedimentological features, probably, the Persian platform's micro-plates stayed together during this period (Davoudzadeh and Schmidt, 1984);(Davoudzadeh and Schmidt, 1984); (Stoecklin, 1968)). Main tectonic events in the Zagros during the Mesozoic The Cimmerian continent is made up of several micro-plates that were isolated from the Persian Platform by the Neo-Tethy Ocean (Stampfli et al., 1991) (Dercourt et al., 1986) (Golonka and Ford, 2000). A horst and graben system could have formed on the northeastern boundary of the Zagros region due to this event (Stampfli et al., 1991) (Weidlich and Bernecker, 2003) during the late Triassic to early Jurassic, the Sanandaj-Sirjan micro plate split from the Arabian Platform. During the late Cretaceous, the tectonic regime between the Sanandaj-Sirjan micro-plate and the Arabian Platform shifted, and the platform transitioned from a passive to a convergent margin setting (Golonka, 2000). Plate tectonics in the Zagros throughout the Cenozoic Era The Arabian platform stage at the end of the Zagros region saw active margin processes. When the Neo-Tethys oceanic domain receded on the margins during the Upper Cretaceous, the stage of the Arabian platform came to an Arabian platform stage ended. In addition, subsidence beneath the northern margin during this period caused the Neo-Tethys' circumference to narrow (Golonka, 2000) gradually. These incidents resulted in establishing the Zagros Foreland Basin phase, which is still ongoing today (Sepehr and Cosgrove, 2004; Sepehr et al., 2006; Sharland et al., 2001) tertiary strata deposited in a constrained, northwest-southeast foreland basin during this phase, distinguished by its development. During the Zagros orogeny, the Arabian Plate eventually collided with the Iranian micro-continent, shutting the Neo-Tethys Ocean and creating the fold-and-thrust belt of the Zagros Mountains (Alavi, 1994) (Golonka, 2000). The Zagros' tilting upper-Pliocene Bakhtyari conglomerates (Hessami et al., 2001) point to a recent folding. It is compatible with a sequence of deep, narrow, parallel gorges carved into mountain fronts and the deposition of more than 250 m of alluvial deposits. Download 0.84 Mb. Share with your friends:
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