The development of a pull-apart basin in response to collision of the irregular South China continental margin with Indochina

The collision of Indochina and South China has played a significant role in shaping the current tectonic configuration of mainland Southeast Asia. However, its specifics are still debated. To better constrain the development and nature of the collision, we conducted a study of the Shiwandashan basin in the southwestern South China block that employed integrated basin analysis methods including detrital zircon provenance analysis. The Shiwandashan basin is ∼200 km long and 60 km wide, and features a V-shaped cross-sectional profile. Our study reveals that the Lopingian Series in the basin thickens rapidly from the northwestern and southeastern edges toward the center of the basin. The formation of the basin appears to have been influenced by intense compressive strike-slip faults during the Lopingian Epoch. However, the sedimentary structures within the basin also display characteristics consistent with an extensional setting, including slump deposits and soft-sediment deformation, alon...