Paleozoic−Mesozoic tectonic evolution of the Wugong Shan region, South China

The growth and evolution of the South China continent involved multiple, progressive tectonic processes during the Phanerozoic, including early Paleozoic orogeny and Mesozoic plate-margin activity associated with the Paleo-Tethyan and Paleo-Pacific oceanic realms. These overprinting tectonic events resulted in complicated rock assemblages and deformation patterns. The construction of the southeastern South China continent remains poorly understood particularly because early Paleozoic tectonism was modified by Mesozoic magmatism and deformation. In this study, we investigated the geology of the Wugong Shan region within the South China continent, which has experienced a protracted tectonic evolution since the Neoproterozoic. We combined new and published field observations, geochronological results, and geochemical and Sr-Nd isotopic data to constrain the chronostratigraphic framework and timing of Phanerozoic magmatism. Detrital zircon U-Pb results for thermal-contacted metasedimentary rocks suggest that Neoproterozoic−Ordovician strata were metamorphosed by the intrusion of early Paleozoic granitoids. Zircon U-Pb, whole-rock geochemical, and Sr-Nd isotopic results show that the Wugong Shan region experienced two dominant stages of magmatism at ca. 467−417 Ma and ca. 168−149 Ma. These stages involved the generation of S-type granites via partial remelting of Archean−Proterozoic continental crust. We integrated these results into a revised model for the Paleozoic−Mesozoic tectonic evolution of the Wugong Shan, which initially involved Middle Ordovician−Silurian intracontinental deformation associated with early Paleozoic plate-margin tectonic activity along the Wuyi-Yunkai orogenic belt in the South China continent. This was followed by the Triassic collision of the South and North China continents and Jurassic−Cretaceous plate-margin magmatic activity during the westward subduction of the Paleo-Pacific oceanic slab. The Wugong Shan is a Jurassic magmatic-metamorphic dome that formed locally and was exhumed due to subduction-related magmatism.