花岗岩锆石U-Pb年龄与全岩Rb-Sr等时线年龄对比研究及其地球化学意义

花岗岩锆石U-Pb年龄与全岩Rb-Sr等时线年龄对比研究及其地球化学意义

吴俊奇，章邦桐，凌洪飞，陈培荣

南京大学内生金属矿床成矿机制研究国家重点实验室及地球科学系，南京 210093

收稿日期:2007-06-20 修回日期:2007-06-20 出版日期:2007-06-20 发布日期:2007-06-20

Comparison between the Zircon U-Pb Ages and the Whole-Rock Rb-Sr Ages of Granite Plutons and Its Geochemical Implication

WU Jun-qi, ZHANG Bang-tong, LIN Hong-fei and CHEN Pei-rong

State Key Laboratory for Mineral Deposits Research and Department of Earth Sciences,Nanjing University, Nanjing 210093, China

Received:2007-06-20 Revised:2007-06-20 Online:2007-06-20 Published:2007-06-20

摘要/Abstract

摘要： 对国内外32个花岗岩体的锆石U-Pb年龄与全岩Rb-Sr等时线年龄之间差值（Δt）进行的频数统计分析表明：Δt呈对称正态分布（偏度系数CSK=0.36；峰度系数CKU=2.99）；年龄差（Δt）既呈正值又有负值，其均值为2.08Ma；相对年龄差（Rt）小于5%。采用最小二乘法计算，花岗岩体锆石U-Pb年龄（tZr）对全岩Rb-Sr等时线年龄（tRb）拟合出相关系数很高（r=0.998），回归系数接近l（α=1.003）的线性回归方程（tRb =1.003tZr +1.258）。这些统计特征表明，从总体来看，花岗岩体的Rb-Sr等时线定年测定结果与锆石U-Pb定年测定结果是一致的，花岗岩全岩Rb-Sr等时线定年方法是成熟、可信的，同时也为花岗岩锆石U-Pb年龄代表结晶年龄而不代表花岗岩侵位年龄提供了依据。

Abstract: The frequency analysis of age difference (Δt) between the results of zircon U-Pb dating and whole rock Rb-Sr dating for 32 granite plutons shows that the Δt displays a symmetrical normal distribution (skewness C sk=0.36; kurtosis C ku=2.99) in the histogram. The Δt is both positive and negative, with a mean of 2.08 Ma, and the percentage of age difference is less than 5% (absolute value). Using least squares regression procedure, a best regression equation with high correlation coefficient (r=0.998) and regression coefficient close to 1 (a=1.003) is fitted to the points of the zircon U-Pb ages and the whole rock Rb-Sr ages for 32 granite plutons. These statistic characteristics indicate that the zircon U-Pb dating ages are corresponding with the whole-rock Rb-Sr isochron ages for granites as a whole. The whole-rock Rb-Sr isochron dating method for granites is mature and reliable. the zircon U-Pb age cannot represent the emplacement ages of granites, but the crystallization age.

吴俊奇，章邦桐，凌洪飞，陈培荣. 花岗岩锆石U-Pb年龄与全岩Rb-Sr等时线年龄对比研究及其地球化学意义[J]. J4.

WU Jun-qi, ZHANG Bang-tong, LIN Hong-fei and CHEN Pei-rong. Comparison between the Zircon U-Pb Ages and the Whole-Rock Rb-Sr Ages of Granite Plutons and Its Geochemical Implication[J]. J4.