Based on the element diffusion theory and analysis to the experiment of U-Pb diffusion in zircon, it is confirmed that
the“closure temperature of U-Pb isotope system in natural zircon >900 ℃”drawn from experiment of U-Pb diffusion in zircon by heating zircon crystals done by Lee et al. (1997) and Cherniak et al. (2000) can not be applied to the zircon crystallization process from the granitic melt. Using least squares regression procedure, a best regression equation (tZr= 1.00346tAr-1.03511) with high correlation coefficient (R=0.996) is fitted for 514 pairs of zircon U-Pb age and hornblend-biotite Ar40/Ar39 age of granite plutons world wide. The PDF of the frequency analysis for these granite plutons shows symmetrical normal distribution with skewness coefficient(CSK)-0.16. These statistical characteristics cofirmed that the zircon U-Pb age can not represents the emplacement age of a granite pluton, but represent crystallization age also. According to the time difference elapsed from granite melt to crystallization , (ΔtECTD) , these ΔtECTD (emplacement crystallization time difference) of 9 plutons were 52.0 my (Jiufeng), 26.1 my

(Xishan), 28.6 my (Jingjiling), 39.3 my (Guidongxiti), 42.7 my (Qitianling), 45.7 my ((Huashan), 42.7 my ((Guposhan), 9.74 my ((Pitou), 16.4 my (Zhaibei), respectively. Based on the zircon U-Pb ages, ΔtECTD of these granitoids and inversion calculation, these emplacement ages of 9 plutons in Nanling Rang were 219.4 my (Jiufeng), 182.1 my (Xishan), 184.6 my (Jingjiling), 199.4 my (Guidongxiti), 203.7 my (Qitianling), 207.7 my (Huashan), 205. 7 my (Guposhan), 192 my (Pitou), 190.2 my (Zhaibei), respectively. These data contribute important evidences to the Indosinian cycle emplacement of the Early Yanshanian plutons in Nanling Rang and display the double magmatic-tectonic features in NR i.e. the E-W trending Indosinian tectonic framework(representing by tE ) and the Early Yanshan granite plutons (representing by tC).