Timing and forcing mechanism of the final Neotethys seawater retreat from Central Iran in response to the Arabia-Asia collision in the late early Miocene

• Published in: Global and Planetary Change
• Main Authors: Sun, Jimin, Talebian, Morteza, Jin, Chunsheng, Liu, Weiguo, Zhang, Zhiliang, Cao, Mengmeng, Windley, Brian F., Sheykh, Morteza, Shahbazi, Reza, Tian, Shengchen
• Format: Report
• Language: English
• Published: ELSEVIER 2021
• Subjects: Land-sea change; Qom back-arc basin; Magnetostratigraphy; Paleoclimate; Neogene; QOM FORMATION; FORAMINIFERAL BIOSTRATIGRAPHY; BENTHIC FORAMINIFERA; CLIMATIC TRANSITION; EURASIA COLLISION; EARLY OLIGOCENE; ZAGROS; BASIN; REMAGNETIZATION; EVOLUTION; Physical Geography; Geology; Geography; Physical; Geosciences; Multidisciplinary; East Antarctica; Antarc*; Antarctica; Ice Sheet
• Online Access: http://ir.ieecas.cn/handle/361006/15979; https://doi.org/10.1016/j.gloplacha.2020.103395

The Iranian Plateau lies in the middle of the Neotethys tectonic domain; to the east it connects with the Tibetan Plateau, and to the west with the Anatolian Plateau and the Alpine orogenic belts. In the Cenozoic it underwent land/sea changes and tectonic uplift in response to the Arabia-Asia plate collision. One of the most prominent geological consequences of the collision was the disappearance of an epicontinental sea in Central Iran, which was a northeastern branch of the Neotethys seaway in the Oligocene-early Miocene. The timing of the final seawater retreat from Central Iran and its forcing mechanism are important for understanding the effects of Arabia-Asia plate collision as well as global eustatic sea-level changes. In this paper we present new magnetostratigraphy, U-Pb ages of one tuffaceous bed, and stable isotopic records of carbonates. The results of this multidisciplinary study indicate that a shallow open sea in the Qom back-arc basin ended at 17 Ma, but the final seawater retreat from a restricted marine environment was at 16.8 Ma. The final regression was just before the Middle Miocene Optimum, implying that it was not related to a climatic factor, but driven by the Arabia-Asia plate collision. Moreover, the delta O-18 record of fine-grained lacustrine carbonates indicates an isotopic shift towards more positive isotopes after 13 Ma, suggesting an enhanced aridification in Central Iran. This climatic deterioration was a response to reduced transport of moisture by westerlies from a retreating Neotethys Sea driven by a global eustatic sea-level drop in response to the East Antarctica ice-sheet expansion after the middle Miocene Optimum.