The Cretaceous Plutonism In South China:Insights From Regional Petrology And Geochemical Studies

The granite,which is an important part of the Mainland crust,is one of the most widely distributed rocks in Mainland.It records all kinds of information about the formation and evolution of the world Mainland shelf.It is a core content for scientists to study the formation and evolution of the world's Mainland shelf.South China has experienced long-term tectonic evolution and many tectonic superposition,so the granite in this area is not only formed under a single tectonic background,but is influenced by many factors.In recent years,according to the extensive research on the formation process,material composition,chronology and so on,the predecessors summarized the relatively perfect data,and made great breakthroughs in the spatial and temporal distribution of granite,the classification of rock origin,the discrimination of tectonic environment,the origin of matter and so on.A series of digital mapping software,such as Arc GIS,is used to analyze the spatial and temporal distribution,granite type and tectonic environment,zircon saturation temperature and granite material source of Jurassic-Cretaceous granite in South China.The results show that the Jurassic rock mass is located on the west side of Zhenghe-Dapu fault,while the Cretaceous rock mass is mainly distributed at the eastern boundary of the plate,showing a trend of increasing age from coastal to inland.The Cretaceous rock slurry activity intensity can reach 2375 km~3/myr;and the Cretaceous granite in South China is mainly biotite-mica granites,in which the iron index(Fe*)and mafic calc-alkaline peralite granite are the most abundant,one of the two main rock material sources is British diorite and the other is metamorphic sediment;Most of the tectonic environments formed by granite belong to collision-post-collision environment,and some belong to intraplate extension environment,almost no island arc environment.Early-middle Jurassic rock mass mainly occurs in the context of intraplate rift-extension.During the late Jurassic to Cretaceous,large-scale magmatic activity was affected by the multiple subduction,lithosphere extension and plate collision of the Paleo-Pacific plate.In the results of zircon temperature calculation,several higher temperature magmatic regions appeared in South China,mainly along the coast of Yuyao-Zhenghe-Dapu fault,Jinxiu-Xinfeng-Xingning-Yunxiao(south of Nanling)fault.According to the calculated results of crust and mantle material contribution ratio in granite forming material source,the material source is mainly crustal material,crust-mant mixed material,and granite is the main granite type of Cretaceous in South China.