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The U-Th-40 K concentrations of granite are on 1-2 orders of magnitude greater than those of basaltic-ultrabasic rocks. Radiogenic heat of a granitic melt has significant influence on the cooling-crystallization period of the melt. In this paper we derived a formula to calculate prolongation period (t A ) of cooling-crystallization of a granitic melt caused by radiogenic heat. Calculation using this formula and radioactive element concentrations (U=5.31×10 −6 ; Th=23.1×10 −6 ; K=4.55%) for the biotite adamellite of the Jinjiling batholith shows that the t A of the adamellite is 1.4 times of the cooling period of the granitic melt without considering radiogenic heat from the initial temperature (T m =960℃) to crystallization temperature (T c =600℃) of the melt. It has been demonstrated that the radiogenic heat produced in a granitic melt is a key factor influencing the cooling-crystallization process of the granitic melt, and is likely one of the reasons for inconsistence between emplacement ages and crystallization ages of many Meso-Cenozoic granitoids.

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