Geodynamic Background of the Mesozoic Intracontinental Magmatism in Southeast China

The authors have proposed a dynamic model in this paper based on the ages,rock series and associations,Sr-Nd isotopic signatures of the Mesozoic intracontinental magmatism overlying the Cathaysian and Yangtze blocks.The model describes the relation of intracontinental collision and subduction in the Tethyan tectonic regie with Paleo-Pacific oceanic plate sudbuction-strike slip-extension in the Pacific tectonic regime.During 220-150Ma,the horizontal collision between the North China block and the Yangtze block,as well as the intracontinental subduction of some divergent microcontinental terranes in the southwestern part of South China are ascribed to the influence of the Tethyan tectonic regime,giving rise to a volume of high-Isr and low-εNd(t) S-type granites only in the Cathaysian Block.During 145-90Ma,under the geodynamic backgound of subduction-strike slip-extension of the Paleo-Pacific oceanic plate on the basis of the deep tectonic process in the Tethyan tectonic regime,high-K,alkalirich calc-alkaline and shoshonitic volcano-plutonic complexes were generated in the Yangtze block,and high-K calc-alkalic and bimodal volcano-plutonic complexes were generated in the Cathaysian block.The occurrence of A-type peralkaline granites in the coastal areas of South east China indicates the end of Mesozoic intracontinental magmatism.

Geodynamic background of the mesozoic intracontinental magmatism in Southeast China

The authors have proposed a dynamic model in this paper based on the ages, rock series and associations, Sr-Nd isotopic signatures of the Mesozoic intracontinental magmatism overlying the Cathaysian and Yangtze blocks. The model describes the relation of intracontinental collision and subduction in the Tethyan tectonic regime with Paleo-Pacific oceanic plate subduction-strike slip-extension in the Pacific tectonic regime. During 220–150 Ma, the horizontal collision between the North China block and the Yangtze block, as well as the intracontinental subduction of some divergent microcontinental terranes in the southwestern part of South China are ascribed to the influence of the Tethyan tectonic regime, giving rise to a volume of high-I_Sr and low-ɛ_Nd(t) S-type granites only in the Cathaysian block. During 145–90 Ma, under the geodynamic background of subduction-strike slip-extension of the Paleo-Pacific oceanic plate on the basis of the deep tectonic process in the Tethyan tectonic regime, high-K, alkali-rich calc-alkaline and shoshonitic volcano-plutonic complexes were generated in the Yangtze block, and high-K calc-alkalic and bimodal volcano-plutonic complexes were generated in the Cathaysian block. The occurrence of A-type peralkaline granites in the coastal areas of Southeast China indicates the end of Mesozoic intracontinental magmatism.