Timing and spatial variation of deformation along the Kanggur-Huangshan shear zone in the Chinese Tianshan: Implications for regional differential uplift and mineralization

Abstract

The Chinese Tianshan experienced large-scale transcurrent tectonics, synkinematic emplacement of ultramafic to felsic intru-sions, and the formation of various mineral deposits during late Paleozoic accretionary orogenesis. The relationships among the spa-tial variation of deformation, the distribution of Permian orogenic Au and magmatic Ni-Cu sulfide deposits, and the kinematic evolution of crustal-scale shear zones, however, remain ambiguous. To address these ambiguities, the spatial variation in the degree of deformation in the Kanggur-Huangshan shear zone in the Chinese Tianshan was characterized using detailed structural measurements and zircon U-Pb and muscovite 40Ar/39Ar age data. The new structural data indicate that a prominent spatial variation exists in the style of defor-mation throughout the Kanggur-Huangshan shear zone; intense ductile deformation struc-tures are dominant in the east, while brittle structures become progressively more domi-nant toward to the west. Zircon U-Pb and muscovite 40Ar/39Ar age data for syn- and postkinematic intrusions along the Kanggur-Huangshan shear zone indicate that dextral strike-slip shearing occurred between 279 Ma and 249 Ma. The spatial variation in the de-gree of deformation and exhumation along the Kanggur-Huangshan shear zone was po-tentially caused by regional differential uplift induced by the collision of the Tianshan and Beishan regions; this was likely responsible for the predominant occurrence of magmatic Ni-Cu sulfide deposits in the eastern portion of the Kanggur-Huangshan shear zone and orogenic Au deposits in the western portion. The identified spatio-temporal relationship between deformation and distribution of oro-genic Au and magmatic Ni-Cu sulfide deposits is crucial to the future success of mineral ex-ploration in the Central Asian orogenic belt.