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- Author or Editor: Majid Sudi Ajirlu x
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In this paper we reconstruct the tectonic evolution of Eastern Turkey, the Lesser Caucasus and NW-N Iran from the Late Carboniferous to Recent. NW Iran is one of the most complicated regions of the country, that with Turkey and the Lesser Caucasus is influenced by movements of the Arabian Plate. The Ahar Block, which is bounded by the Tabriz, Talysh, Araks, Myaneh and Allahyarlu-Hovai Faults, underwent compression and faulting. The block shows counterclockwise rotation through the confining faults and is being compressed by northward pressure from the Arabian Plate. The age and the nature of the Allahyarlu ophiolite, which is located at the northern boundary of the Ahar Block, are not known unequivocally. During the Late Carboniferous the Allahyarlu-Kaleybar-Northern Iran Basin opened, and Neotethys 1 was spreading. During the Permian the Allahyarlu-Kaleybar-Northern Iran Basin changed from a passive to a convergent environment and closed at Late Triassic to Early Jurassic time. In the Early Jurassic Neotethys 1 began to be subducted, causing the opening of the Sevan-Akera back-arc basin. Thereafter the Sevan-Akera Basin and the Neotethys 2 Basin were widening up to the Late Jurassic. The Black Sea-South Caspian Sea-Kopet Dagh Basin opened during the Jurassic. These basins were widening up to the Paleocene, but northward slider replacement of NW Iran caused the separation of the Caspian Sea Basin and the Black Sea Basin and the formation of the Kurdamir Uplift. In the Late Cretaceous the Central Iran basins were closed and the inner-Iran ophiolites were emplaced. Neotethys 1 closed in the Late Cretaceous and Neotethys 2 in the Late Miocene.
The Zagros Orogenic Belt includes the Fold and Thrust Belt, the High Zagros Belt, the Outer Zagros Ophiolitic Belt, the Sanandaj–Sirjan Metamorphic Belt, the Inner Zagros Ophiolitic Belt, and the Urumieh–Dokhtar Magmatic Belt. We divide the High Zagros evolutionary history into five stages: (1) triple junction formation, (2) continental lithosphere rifting, (3) generation, spreading, and maturation of the Neotethys Ocean, (4) subduction of the oceanic lithosphere, and (5) collision. The Neotethys triple junction, located at the southeastern corner of the Arabian Plate, formed during the Late Silurian–Early Carboniferous. Subsequently, this triple junction became a rift basin due to normal faulting and basalt eruption. The rifting stage occurred during the Late Carboniferous–Early Permian. Thereafter, extension of the basin continued, leading to spreading and maturation of the Neotethys oceanic basin during the Late Permian–Late Triassic. Probably at the end of the Late Triassic, closure of the Paleotethys Basin caused the initiation of two northeastward subductions: (1) oceanic–oceanic and (2) oceanic–continental. Oceanic–oceanic subduction continued until the Late Cretaceous and was terminated by the emplacement of the Outer Zagros Ophiolites, whereas oceanic–continental subduction continued until the Middle Miocene. Subduction in the southern Neotethys Basin between the Arabian and Central Iran Plates caused a tensional regime between Sanandaj–Sirjan and Central Iran, and the formation of a back-arc basin that by its closing led to the emplacement of the Inner Zagros Ophiolites during the Late Cretaceous.
