Tectonic evolution of the foreland basin of the SE Alborz Mountains, northern Iran

• Published in: Journal of Asian earth sciences 2022-01, Vol.223, p.104981, Article 104981
• Main Authors: Naeimi, Amir, Alavi, Seyed Ahmad, Madanipour, Saeed
• Format: Article
• Language: English
• Subjects: Arabia-Eurasia collision; Foreland basin; Reverse kinematics; SE Alborz Mountains
• ISSN: 1367-9120; 1878-5786
• DOI: 10.1016/j.jseaes.2021.104981

[Display omitted] •The North Semnan Fault has thrust the SE Alborz Mountains on the foreland basin.•The reverse reactivation of the Attary Fault has disrupted the foreland basin.•A NW-oriented compression is suggested for the post-Eocene faults.•Deep-seated thrusting occurs along the flanks of the Alborz Mountains.•Motions of the South Caspian Basin relative to Iran affect the regional kinematics. Along the SE Alborz Mountains in northern Iran, thrust loading seems to have been accompanied by post-Eocene transversal left-lateral faulting during the late Cenozoic. Here, the range-front North Semnan Fault has played a major role in the thrust loading and the development of the foreland basin. This fault has placed the Cenozoic succession upon the foreland basin from the early Miocene to the present. It is linked to the Peyghambaran Fault as the back thrust that began its reverse kinematics sometime between the middle Miocene to the latest Pliocene-Quaternary times. The foreland basin of the SE Alborz Mountains was later disrupted as a result of the reverse reactivation of a south-dipping pre-existing structure known as the Attary Fault during the latest Pliocene-Quaternary times. This fault cuts through the Pliocene-Quaternary deposits and exhibits left-lateral kinematics as well. It is suggested that the Arabia-Eurasia collision and the regional kinematic changes in the South Caspian Basin explain the reverse reactivation and the onset of the left-lateral kinematics along the Attary Fault. The above-mentioned post-Eocene transversal left-lateral faulting in the SE Alborz Mountains is compatible with a NW-oriented compression at the time. This indicates the rotations of the structural trends or a change in the direction of compression since then. Our findings revealed that contractional deformation is still active in the SE Alborz Mountains. It is also proposed that the foreland basin is not yet capable of underthrusting beneath the Alborz Mountains despite having a relatively thick basin fill.