The main Paleo-Tethys Ocean suture in the Pamir Region: Revealed by detrital zircon U–Pb geochronology

Abstract

The Pamir Plateau offers valuable insights into the evolution of the Tethys Oceans. Despite numerous studies, the nature and timing of closure of the Paleo–Tethys Ocean remain debated. This study presents detrital zircon U–Pb ages of sedimentary rocks across the Pamir terranes to investigate their tectonic evolution. Detrital zircons from the Paleozoic–Triassic sedimentary succession in the Northern and Central Pamir yielded similar results, with ages ranging from ∼ 233 Ma to 1000 Ma, showing two major peaks one at ∼ 250 Ma and another at 540–600 Ma. Zircons giving these two age peaks are subhedral to anhedral, implying they were likely derived from arc–related magmatic rocks, possibly formed by the subduction of the Paleo–Tethys oceanic lithosphere. In contrast, detrital zircons from the Late Triassic sandstone in Southern Pamir reveal a major peak at 237 Ma, with subordinate peaks at ∼ 430 Ma and 540 Ma, indicating their detritus was largely sourced from the Central Pamir. Age patterns of the detrital zircons from the Northern–Central Pamir and South Pamir are similar to those of the North and South Qiangtang, respectively, indicating that the Rushan–Pshart suture zone was the main suture of the Paleo–Tethys, and the Tanymas suture zone was the back–arc basin of the Paleo–Tethys Ocean.. The obtained data indicate that the northward subduction of the Paleo–Tethys oceanic lithosphere beneath the Northern and Central Pamir was continuous, at least during the Late Devonian to Triassic period, and the collision between the Central and South Pamir was initiated in the Middle Triassic (∼240 Ma).