Tracing the Syn‐Convergence Extrusion Tectonics of the Sulu Orogenic Belt and Its Implication for North China–South China Collision

Understanding the transition from oceanic to continental subduction is critical for reconstructing the geodynamic evolution of orogens and constraining ancient plate boundaries. The Sulu orogenic belt in eastern China was formed by Triassic deep subduction of the South China Block (SCB) beneath the North China Block (NCB). Its architecture was reformed by multi‐phase exhumation of high‐pressure (HP) to ultra‐high‐pressure (UHP) metamorphic rocks, obscuring the early syn‐convergence process. The Stenian to Tonian Wulian group—a non‐(U)HP tectonic unit—likely records the geodynamic process preceding deep continental subduction and is a key to understanding the transition from oceanic to continental subduction. Its debated tectonic affinity (SCB vs. NCB) further constrains the location of the plate boundary. We integrate structural, EBSD, and geochronological and geochemical investigations on the Wulian meta‐sediments. This group comprises a lower amphibolite‐facies unit and an upper greenschist‐facies unit. Detrital zircon U–Pb ages and Lu–Hf isotopic data indicate its affinity for SCBs. Our structural analysis reveals a Late Permian–Early Triassic (ca. 260–250 Ma) norma‐sense shearing, with top‐to‐the‐NNE kinematics accommodating the southward extrusion of the Wulian group. Deformation temperatures were 400–500°C at the lower unit and 280–400°C at the upper unit. By comparison with tectonic events of HP–UHP units, we suggest that the Wulian group was decoupled from subducting SCB during oceanic slab break‐off (ca. 260–250 Ma), while the trailing continental crust continued to subduct and experienced HP–UHP metamorphism. This model implies that the NCB–SCB plate boundary lies north of the Wulian group.