Structural analysis and low-temperature thermochronology of the Ozbak-Kuh Mountains, Central Iran: Constraints on the influence of intraplate strike-slip faulting in the Arabia–Eurasia collision zone

Intracontinental deformation in collision zones is generally localized along basement strike-slip fault zones, resulting in crustal shortening and fault-related exhumation of rocks. Strike-slip faulting plays a key role in accommodating crustal deformation in Central Iran, which is located within the active collision zone between the Arabian and Eurasian plates. This study investigates the impact of basement strike-slip faulting on intracontinental deformation of the Central Iran Microcontinent. These deformations are extensively localized in the Kashmar–Kerman Tectonic Zone (KKTZ). Previous U-Pb radiometric dating and thermochronometric studies from the southern parts of the zone have recorded predominantly Early Mesozoic events, whereas the northern parts document Cenozoic events. However, the central part of the zone, in the Ozbak-Kuh Mountains, has remained poorly constrained. Integration of new structural data with low-temperature thermochronometric data from the Ozbak-Kuh Mountains reveals two distinct cooling events. The first event, dated to the Late Cretaceous–Paleocene (∼55–75 Ma), coincided either with the initial closure of the Neo-Tethys Ocean and obduction of its ophiolites, or with the closure of a back-arc basin located to the north. In either scenario, the driving mechanism reflects a convergent tectonic setting characterized by folding of Paleozoic–Mesozoic rocks and deposition of the unconformable Paleocene Kerman Conglomerate. The second cooling event, which occurred during the late Eocene–Oligocene (∼27–37 Ma), is interpreted to mark the onset of continental–continental collision between the Arabian and Eurasian plates, as evidenced by the development of an angular unconformity between Oligocene–Miocene strata and older rock units. This event also led to transpressional deformation along the Kalmard Fault Zone (KFZ). Accelerated cooling in the western parts of the Ozbak-Kuh Mountains, as indicated by apatite fission-track (AFT) data, highlights the significant role of strike-slip faulting in accommodating oblique convergence.