Magma-dynamic Evidence for Indosinian Emplacement and Tectonic Implication of the Early Yanshanian Granite Batholiths,South China:Based on Estimates of Emplacement Age for the 8 Granite Batholiths in Nanling Range

Based on the geological-tectonic features,the related thermophysical parameters and the radioactive element concentrations for each granite batholith,the simplified cubic mathematic model calculation results suggest that the cooling time from initilal temperature to crystallization temperature(Δtcol) for the 8 Early Yanshanian batholiths in Nanling(NR) Rang were 3.9 Ma(Jingjiling batholith)～5.5 Ma(Jiufeng batholith),the prolongation time caused by latent heat generated from crystallization(ΔtL) were 2.6 ～3.5 Ma and the prolongation time caused by radiogenic heat from decay of the radioactive elements(ΔtA) were 5.2 Ma(Pitou batholith)～45.1 Ma(Guposhan batholith).The time difference elapsed from the magma emplacement to the crystallization(△tECTD) were12.1 Ma(Pitou batholith)～52.2 Ma(Guposhan batholith)for the 8 Early Yanshanian batholiths in Nanling Rang and in combination with the zircon U-Pb ages of these granitoids and inversion calculation,the emplacement ages were 194.4 Ma(Pitou batholith)～219.3 Ma(Jiufeng batholith).These data provide important magma-dynamic evidence for the Indosinian emplacement of the Early Yanshanian batholiths in Nanling Rang and display the double magmatic-tectonic features in NR i.e.,the E-W trending Indosinian tectonic framework( represented by tE) and the Early Yanshan granite batholiths(represented by tC).