关于南岭中生代花岗岩侵位年龄与锆石U-Pb年龄的时差问题:与章邦桐教授等讨论

On the Time Span between Emplacement Age and Zircon U-Pb Age of the Mesozoic Granites in Nanling Range, South China: A Discussion with Prof. Zhang Bangtong et al

从南岭中生代花岗岩的显微结构特征、花岗岩液相线和固相线的已有实验成果、锆饱和温度信息、花岗岩体几何形态以及它们与围岩的接触关系等角度,提出这些花岗岩中锆石结晶温度较高,其结晶年龄与花岗岩岩浆侵位年龄之间的时差较小,很可能在锆石U-Pb年龄测定的误差范围内,因此,花岗岩中锆石的U-Pb年龄,能近似地代表花岗岩岩浆的侵位年龄。

From the view-points of petrographyic micro-structures of the Mesozoic granitic bodies in the Nanling Range, South China, existing experimental results on liqiudus and solidus temperatures of granites, zirconium saturation temperature data, geometric features of granitic bodies and their contact relationships with sedimentary rocks, it is proposed that the crystallization temperatures of zircon in this region are relatively high. The time span between the emplacement ages of granitic magmas and the zircon U-Pb ages of granites might be not very large, and possibly within the range of experimental errors of the zircon U-Pb dating. Consequently, the zircon U-Pb ages may approximately represent the emplacement ages of the corresponding granitic magmas.