Detrital zircon UPb geochronology of the Cenozoic succession in the southern Tarim Basin: Implications for the northward expansion of the West Kunlun Orogen and the evolution of intracontinental convergence in the northwestern Tibetan Plateau

The collision between the Indian and Eurasian plates led to the formation of the Tibetan Plateau and the development of a broad zone of intracontinental deformation. Situated in the northwestern Tibetan Plateau, the West Kunlun Orogen is a key region for examining intracontinental responses to the far-field effects of the India–Eurasia collision. However, the nature of convergence between the Tarim Basin and the West Kunlun Orogen remains uncertain. The West Kunlun Orogen consists of the northern and southern West Kunlun terranes and the Songpan-Ganzi terrane, each exhibiting distinct zircon UPb geochronological signatures. In this study, we apply detrital zircon UPb geochronology and related analyses to nine Cenozoic sediment samples from the Keliyang section and one sample from the Sangju River to investigate source-to-sink relationships and the uplift history of the West Kunlun Orogen. Our results reveal a significant shift in sedimentary provenance, transitioning from sources in the Songpan-Ganzi and southern West Kunlun terranes during the deposition of the Bashibulake, Keziluoyi, Anjuan and Pakabulake formations to the northern West Kunlun terrane during the deposition of the Artux Formation. This shift indicates a northward expansion of the West Kunlun Orogen, accompanied by a migration of the deformation front from the Tam Karaul Fault to the Tiklik Fault. These findings support a transition in convergence dynamics between the Tarim Basin and the West Kunlun Orogen shifted from a crustal-scale coupling mode with pure-shear thickening to a decoupled mode characterised by southward underthrusting of the Tarim Basin's lower crust.