Neoproterozoic amalgamation between Yangtze and Cathaysia blocks: The magmatism in various tectonic settings and continent-arc-continent collision

Abstract

According to the temporal-spatial distribution of Neoproterozoic igneous rocks and relative rocks in South China, including ophiolites, arc volcanic and intrusive rocks and subsequent bimodal magmatism, we identified the presence of a Neoproterozoic intra-oceanic arc, continent-arc-continent collision and three tectono-magmatic zones between the Yangtze Block and Cathaysia Block. We have also unraveled the amalgamation and tectono-magmatic histories between the Yangtze and Cathaysia blocks: At ∼1000–860Ma, northwestward ocean-ocean subduction and southeastward ocean-continent subduction resulted in the intra-oceanic arc magmatism and active continental margin magmatism in the Cathaysia Block respectively. At ∼860–825Ma, the steepening subduction caused development of back-arc basin in the intra-oceanic arc zone and the slab rollback induced the arc and back-arc magmatism in the Cathaysia Block. Meanwhile, a shallow dip northwestward ocean-continent subduction formed active continental margin magmatism in the Yangtze Block. At ∼825–805Ma, the continent-arc-continent collision and final amalgamation between the Yangtze and Cathaysia blocks yielded the Jiangnan Orogen. At ∼805–750Ma, the Jiangnan Orogen collapsed, and the Nanhua rift basin formed. Our study also rules out any Grenvillian Orogenic event and mantle plume activity in South China and indicates a marginal position of South China in the Rodinia supercontinent.