The final collisional orogenesis in accretionary orogens is crucial for reconstructing the whole orogenic circle and understanding the material and energy recycling along convergent margins. However, it is always not straightforward to be addressed, particularly when the final suturing following the ocean closure occurred softly, for instance, the Central Asian Orogenic Belt (CAOB). In this study, a comprehensive dataset of detrital zircon U-Pb ages and Hf isotopes for the Middle Permian to Middle Jurassic foreland sediments from the Linxi region, southeastern CAOB, is synthesized. We observed multiple abrupt changes in sedimentary provenance over time from this dataset: (1) the ca. 275 Ma sediments (Upper Zhesi Fm.) were entirely sourced from the local NAO, whereas the ca. 270–258 Ma sediments (Middle-Upper Linxi Fm.) received an additional detritus contribution from the northern NCC, (2) the ca. 257–236 Ma sediments (Lower-Middle Xingfuzhilu Fm.) returned to a pure NAO source, but the slightly postdated ca. 227 Ma sediments (Upper Xingfuzhilu Fm.) show provenance affinities of both NAO and northern NCC, (3) the ca. 171 Ma sediments (Middle Xinmin Fm.) were exclusively derived from the Late Paleozoic to Early Mesozoic magmas in the NAO and northern NCC with no Early Paleozoic and Precambrian detritus. The above episodic shifts in sedimentary provenance observed in the Linxi region, in conjunction with other regional geological evidence, provide key constraints on the pre- to post-collisional evolution in the southeastern CAOB, including the transition from waning subduction to initial collision, subsequent slab break-off and intracontinental contraction, and the post-collisional extension before the superposition of the Paleo-Pacific tectonic regime. Our results show that understanding the spatio-temporal changes of sedimentary provenance of the foreland basins systems during the plate convergence and orogenic evolution can aid in exploring the final collisional dynamics and evolutionary history in ancient accretionary orogens.

增生造山带的最终碰撞造山作用对于重建整个造山圈和了解沿收敛边缘的物质和能量循环至关重要。然而，解决这个问题总是不容易，特别是当海洋闭合后的最终缝合发生在温和的情况下，例如中亚造山带 (CAOB)。本研究综合了中二叠统至中侏罗统中侏罗统前陆沉积物的碎屑锆石 U-Pb 年龄和 Hf 同位素数据集，该数据集来自 CAOB 东南部临西地区。我们从该数据集中观察到沉积物源随时间的多次突然变化：（1）约。275 Ma 沉积物（上柘寺组）完全来自当地的 NAO，而 ca。270～258 Ma沉积物（临西中上组）) 收到来自北部 NCC 的额外碎屑贡献，(2) ca。257-236 Ma 沉积物（下-中兴府之路组）返回纯 NAO 源，但略晚于 ca。227 Ma 沉积物（上幸福之路组）显示 NAO 和华北克拉通北部的物源亲和性，（3）约。171 Ma沉积物（中新民组）仅来源于北华东和华北克拉通北部晚古生代至早中生代岩浆，无早古生代和前寒武纪碎屑。在临西地区观察到的上述沉积物源的阶段性变化，结合其他区域地质证据，为 CAOB 东南部碰撞前后的演化提供了关键约束，包括从减弱俯冲到初始碰撞的过渡，随后的板片断裂和大陆内收缩，以及古太平洋构造体系叠加前的碰撞后伸展。我们的研究结果表明，了解板块辐合和造山演化过程中前陆盆地系统沉积物源的时空变化，有助于探索古代增生造山带的最终碰撞动力学和演化历史。