STUDY OF SOURCES OF PALEOZOIC GRANITOIDS AND THE BASEMENT OF SOUTH CHINA BY MEANS OF Nd-Sr ISOTOPE
Huang Xuan (Institute of Geology, Academia Sinica, Beijing, 100011) D.J. DePaolo(Dept. of Earth & Space Sciences, UCLA, LA, CA 90024, USA)
The classification of ages shows that two periods from Ordovician to Devonian and from Permian to Triassic were significant for the granitoids of South China (Fig.2). The Nd-Sr isotopes of Paleozoic granitoids from South China reveals that sources of the granitoids were likely the old basement of terrain (Fig.3). And according to the trend of evolution of E_(Nd)(0) of granitoids with era, it was suggested that the ages of the old basement of terrain be 1.5--20 Ga(Fig. 4). The algebraic deductions based on the correlation between E_(Nd)(0) of granitoids and era suggest that there is a kind of granitoids the genesis of which was closely related to the mantle, and that the deriving of granitoids from mantle (Fig, 5) happend continually in the history of the Earth(Fig. 4).