Mesozoic–Cenozoic Thermochronology of the Tarim–Southern Tianshan System, <scp>NW</scp> China

ABSTRACT The Tarim Basin, an oil‐bearing basin in northwest China, is tectonically and sedimentologically linked to the Southern Tianshan Orogenic Belt. This study investigates the coupling mechanism between the Tarim Basin and the Southern Tianshan using low‐temperature thermochronology, with a focus on its influence on the basin's tectonothermal evolution and hydrocarbon processes. The thermochronological results provide several key insights: (1) The central AFT ages of the core samples range from 156.9 Ma to 46.0 Ma. Single‐grain AHe ages vary between 15.66 Ma and 0.10 Ma, while single‐grain ZHe ages range from 276.9 Ma to 129.6 Ma. For the surface outcrop samples, single‐grain AHe ages range from 22.96 Ma to 3.10 Ma. The majority of the single‐grain AHe ages show some degree of dispersion, and the ZHe ages of most samples exceed their corresponding stratigraphic ages. (2) A thermal history model for the Kuqa Depression was established based on AHe (apatite (U–Th)/He) and AFT (apatite fission track) age data from core samples. The model reveals that the AHe closure temperature is 80°C ± 5°C, while the AFT closure temperature is 140°C ± 5°C, indicating non‐zero ages for the AHe and AFT systems at temperatures 5°C–30°C above the nominal closure temperatures. (3) Reverse thermal modelling indicates that the Tarim–Southern Tianshan system experienced multi‐stage exhumation (or burial) during the Mesozoic–Cenozoic, influenced by distant tectonic events such as the collision of the Qiangtang and Lhasa plates with the southern margin of Eurasia. The Southern Tianshan underwent three primary exhumation stages: the Middle Triassic–Early Jurassic, Early Cretaceous, and Paleogene–present. The northern margin of the Tarim Basin experienced two major exhumation phases, during the Late Cretaceous and the late Miocene to present. Tectonic uplift in the Tarim Basin occurred much later than in the Southern Tianshan, reflecting a shift in deformation from the orogenic belt to the basin. (4) The coupling between the basin and mountain range has had a profound impact on the thermal history and petroleum system of the Tarim Basin. This coupling controls the present‐day terrestrial heat flow within the basin, influencing the maturity of source rocks and the distribution of oil and gas. During the late Himalayan period, basin–mountain coupling led to the formation of numerous new faults, unconformities, and associated traps in the depression, which facilitated the generation and accumulation of large‐scale hydrocarbon resources. However, this coupling also modified and disrupted some pre‐existing oil reservoirs.