Geochronology and geochemistry of the Cryogenian sedimentary rocks and Early Paleozoic mafic dykes of the South Qinling belt: Implications for the tectonic evolution of the northwestern South China craton

Abstract

The late Paleozoic–Mesozoic tectonic evolution of the Central China orogen between the North China and South China cratons was key in the growth of the Asian continent. The preceding Proterozoic–Early Paleozoic geologic history of the Central China orogen is comparatively less well understood yet critical to resolving preconditions for the assembly of Asia. The South Qinling belt located within the Central China orogen exposes a spectacular record of Cryogenian supracrustal sedimentary rocks and Early Paleozoic intermediate-mafic rocks that are related to the development of the northwestern South China craton. In this study, we investigated the Cryogenian sedimentary rocks and Early Paleozoic magmatic dykes/sills in the Daba Shan of the South Qinling belt to provide new constraints on the tectonic evolution of the orogen in the context of the Paleo-Tethyan domain. We report that Cryogenian sedimentary rocks predominantly contain ca. 850–695 Ma detrital zircon grains, which suggests that these short-transported materials were sourced from the northwestern South China craton. Gabbroic dykes that intrude Neoproterozoic rocks have UPb zircon ages ca. 458–446 Ma, which we interpret reflects the timing of regional crustal extension. Geochemical and SrNd isotopic data indicate that Early Paleozoic gabbroic dykes were sourced from the enriched mantle, possibly associated with an upwelling plume that interacted with the lithosphere along the northern margin of the South China craton.