An analysis of principal features of tectonic evolution in South China Block

Studies suggest that at least four stages of regional-scale tectonic and magmatic events have taken place in the South China block, namely, geodynamic processes of Neoproterozoic and Late Mesozoic active continental margins, Early Paleozoic and Early Mesozoic intracontinental orogenies. The Cathaysia block was a pre-Nanhua basement consisting mainly of Neoproterozoic rocks instead of a stable old land. It experienced a complex evolution from assembly through break-up to re-assembly. The intracontinental shortening during Silurian led to the stabilization of the united South China continent. The entire South China Block was under a shore-shallow sea-slope setting, with no translithospheric fault, no regional-scale volcanism and mantle-derived magmatism in the period from Sinian to Jurassic, during which polyphase tectonic and magmatic events occurred in the united South China lithosphere. It evolved into a part of the Late Mesozoic Western Pacific active continental margin after the Early-Middle Jurassic transformation from Tethysian to Pacific tectonic regimes. The South China lithosphere experienced polyphase continental growth due to the dominant lateral accretion of block assembly accompanied by vertical growth of magma up-swarming. During the Cretaceous, the South China basin and range tectonics occurred in the western shore of the Pacific Ocean due to strong intracontinental extension caused by the northwestward subduction of the Pacific Ocean. Long-term intraplate tectonism and polystage granitic magmatism provided South China with a favorable condition of metallization, forming various large-size ore deposits and resources. Neoproterozoic Nanhua Period and Early Cretaceous were two dominant stages of metallization, with various types of ore deposits being chiefly formed in the Early Cretaceous period.