The U-Th-40K 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 perio...The U-Th-40K 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°C) to crystallization temperature (T c=600°C) 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.展开更多
基金Supported by the National Natural Science Foundation of China (Grant Nos. 40372036 and 40221301)
文摘The U-Th-40K 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°C) to crystallization temperature (T c=600°C) 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.
