A preliminary study of the relationship between granitoids and the growth of continental crust: a case study of the formation of key orogen granitoids in China

Abstract：Based on the achievements concerning the formation of granitoids in the East Kunlun orogenic belt, Qinling orogenic belt, Xingmeng orogenic belt, Altay orogenic belt, Yanshan orogenic belt and South China peraluminous granitoids, this paper has dealt with the formation of key orogenic zone granitoids in mainland China and the continental crust growth and reached some preliminary conclusions: the input of the asthenosphere（mantle convection）thermal materials to the mainland made up the foundation of the growth and reworking of the earth's crust. The formation, evolution and reworking of the continental crust mainly underwent magmatism, whose formation, migration and positioning made up the basic process of continental crust growth. Mantle-derived basaltic magma underplating on the bottom of the continental crust and intraplating within the crust constituted the basic form of the input of the asthenosphere to the mainland. Delamination of mafic orogenic belt in the lower crust was the key mechanism, which made the continental crust composition chemically intermediate (andesite and diorite, or trachyte andesite and monzonitic rock). The contraction extrusion tectonism thickened the continental crust to ≥50 km, which was the necessary prerequisite for inducing delamination of the mafic lower crust. The igneous tectonic assemblage and its time series seem to be the key to identifying the separation of the continental crust from the mantle asthenosphere until the eventual formation