Abstract:The frequency analysis of 64 coupled age differences(Δt=tZr-tRb)between the zircon U-Pb age(tZr) and whole rock RbSr age (tRb)for granite plutons shows that theΔt histogram displays a symmetrical normal distribution (skewness CSK=0.150; kutrocess CKU=4.274); theΔtare both positive and negative with mode 2.0Ma, but far less than the period of cooling—crystallization (>16 Ma)of a granitic batholith. Using least squares regression procedure, a best regression equation (tRb=0.99354tZr +2.15163) with high correlation coefficient (r=0.997) is fitted to the 64 points of the zircon UPb age and the whole rock RbSr age for granite plutons. The constant of this regression equation (2.15163Ma) is consistent with theΔt mode (2.0Ma) for the main. These statistical characteristics indicate that the zircon U-Pb dating age is corresponded with the wholerock Rb-Sr isochron age for granite as a whole and the zircon U-Pb dating age cannot represents the emplacement age of a granite batholith.