Oblique collision between North and South China recorded in Zhangbaling and Fucha Shan (Dabie-Sulu transfer zone)

The Zhangbaling metamorphic belt and the Fucha Shan metamorphic zone are metamorphic terranes that occur along the Tan-Lu fault, the major strike-slip fault that separates the ultra-high-pressure metamorphic belts of Dabie Shan and Sulu in SE China. The greenschist-facies Zhangbaling metamorphic belt is characterized by subhorizontal foliation, belt-parallel lineation, and a top-to-south sense of shear; ⁴⁰ Ar/ ³⁹ Ar analysis of synkinematic white mica dates deformation at ca. 235-240 Ma, coeval with reported peak metamorphic ages of ultra-high-pressure metamorphism in Dabie Shan. The Fucha Shan metamorphic zone is composed of felsic to mafic mylonite and is characterized by subvertical foliation and subhorizontal lineation. Ductile fabrics record a sinistral sense of shear and provide evidence of a zone-perpendicular contraction. Fabric-forming biotites yield ⁴⁰ Ar/ ³⁹ Ar cooling ages of ca. 120 Ma to ca. 135 Ma. The lower-amphibolite-facies Fucha Shan zone may represent an Early Cretaceous transpressional shear zone that developed independent of the Zhangbaling belt. Alternatively, the Zhangbaling belt might have operated as an attachment zone coupling transpressional shear in the underlying Fucha Shan zone with brittle upper crustal deformation during Triassic movement on the proto-Tan-Lu shear zone. Deformation may have been associated with oblique convergence between South and North China. In this model, Early Cretaceous argon ages from the deeper Fucha Shan zone are thought to record a later exhumation event.