Geodynamic Evolution of the South Caspian Basin

Abstract

The South Caspian Basin was formed as a result of the interaction of the Eurasia, India, Arabia, and numerous microplates starting from the Triassic. During the Late Triassic–Early Jurassic, several microplates were sutured to the Eurasian margin, closing the Paleotethys Ocean. A Jurassic–Cretaceous north-dipping subduction was developed along this new continental margin south of the Pontides, Trans-Caucasus, and Iranian plates. This subduction zone trench-pulling effect caused rifting, creating the back-arc basin of the Greater Caucasus–proto-South Caspian Sea, which achieved a maximum width during the Late Cretaceous–early Paleogene. During the Eocene, the Lesser Caucasus, Sanandaj-Sirjan, and Makran plates were sutured to Trans-Caucasus–Talesh–South Caspian–Lut system. The subduction zone jumped to the Scythian-Turan margin. The South Caspian underwent reorganization during the Oligocene–Neogene. Northward movement of the South Caspian microcontinent (SCM) resulted in rifting between SCM and Alborz plate. The southwestern part of the South Caspian Basin was reopened, whereas the northwestern part was gradually reduced in size. The source rocks of the Maikop Formation were deposited in the South Caspian Basin during the Oligocene–early Miocene. The collision of India and the Lut plate with Eurasia caused the deformation of Central Asia and created a system of northwest–southeast wrench faults. The remnants of the Jurassic–Cretaceous back-arc system oceanic and attenuated crust, as well as Tertiary oceanic and attenuated crust, were locked between adjacent continental plates and orogenic systems. Thick molasse-type sediments that accumulated during the Pliocene–Quaternary provided reservoir rocks and contributed to the burial and maturation of source rocks.