Impact of Slab Rollback on the Surface of Overriding Plate: Late Cretaceous Extension and Topographic Evolution to the West of the Xuefeng Orogen in the South China Block

AbstractThe South China block (SCB) preserves abundant evidence of Mesozoic magmatism, extensional basins, and intracontinental deformation that is crucial for understanding the influence of subduction dynamics on surface processes of the overriding plate. However, no consensus has yet been reached regarding the Late Mesozoic geodynamic interpretation of the SCB interior because Late Cretaceous structural and sedimentary records to the west of the Xuefeng orogen are poorly understood. In this study, field structures, paleocurrent directions, heavy mineral assemblages, sandstone petrography, and detrital zircon U‐Pb ages of the Late Cretaceous Jianshi, Enshi, Laifeng, and Qianjiang basins are reported. A NW–SE extensional tectonic regime is inferred from fault‐slip inversion results of the basins. Paleocurrent directions are found to be dominantly from the SW and SE. Heavy mineral analysis indicates that the sources of sandstones in the basins are mainly sedimentary and metamorphic rocks. The sandstone composition and zircon U‐Pb ages are also similar between the basins and surrounding source areas showing the sources from the Sichuan basin and Xuefeng orogen. Considering the westward paleocurrents from topographic highlands into the Sichuan basin during the Jurassic‐Early Cretaceous in the previous work, we propose that slab rollback caused the regional extension, topographic evolution, and the change in paleocurrent direction during the Late Cretaceous. The impact of the slab rollback on the lithospheric extension of the SCB extends to the west of the Xuefeng orogen, with the Late Cretaceous extensional basins potentially marking the westernmost product of lithospheric thinning.