Tectonic evolution records closure of the Western Kunlun–Pamir Paleo-Tethys Realm: Insights from provenance analyses of Jurassic siliciclastic strata

Abstract Determining the provenance history of Jurassic sediments in the southwestern Tarim Basin is crucial for deciphering the tectonic evolution of the Western Kunlun–Pamir Paleo-Tethys Realm, which forms the northwesternmost segment of the Himalayan-Tibetan Plateau. Yet, the detailed spatial provenance variation of these strata is poorly constrained. This study integrates field observations from three outcropping sections (cumulative thickness of ~6800 m) and three wells (~3600 m) from four distinct regions: Qimgan, Oytag, Toyunduk-Kyzyltau, and Fusha. Samples were collected for analysis of sandstone petrology (n = 54), heavy mineral assemblages (n = 18), and detrital zircon U-Pb geochronology (n = 10) to delineate the spatial differences in Jurassic provenance. The results indicate that the southwestern Tarim Basin can be demarcated into two tectonic domains: (1) Detrital zircons in the Qimgan and Oytag regions were predominantly derived from nearby Triassic backarc volcanic rocks. Additionally, late Paleozoic subpopulations were sourced from a volcanic sequence exposed in the northeastern part of North Pamir Terrane, induced by Carboniferous–Permian Paleo-Tethys subduction. North Pamir Terrane served as the main elevated source area, with negligible contributions from Central and/or South Pamir terranes. (2) The detrital zircons of early Paleozoic and Neoproterozoic ages from the Toyunduk-Kyzyltau and Fusha regions predominantly originated from the North Kunlun and South Kunlun terranes in response to Triassic collisional orogeny that induced significant uplift, effectively disconnecting the more distant provenance areas of the Tianshuihai and/or Songpan-Ganzi terranes. Insights from provenance analysis permit the delineation of a refined geodynamic model for the tectonic evolution of the closure of the Western Kunlun–Pamir Paleo-Tethys Realm. This study demonstrates Triassic backarc volcanism in the northeastern Chinese Pamir region, which supports a previously proposed hypothesis. These findings not only deepen our insights into the tectonic evolution of the Western Kunlun–Pamir Paleo-Tethys Realm but also significantly enhance our understanding of the dynamics of sedimentary basins, crustal development, and resource prospecting within convergent orogenic settings.