NEUTRON ACTIVATION ANALYSIS OF GRANITOIDS

From the rare earth element (REE) patterns and Ba, Rb, and Sr relationships of granitoids of South Korea and Southwest Japan, we have found two types of granitoid magmas. These are: 1) Granitoid magmas mainly differentiated by the process of fractional crystallization. These are typified by the Cretaceous granitoids of South Korea and the granitoids younger than Cretaceous in Southwest Japan; and 2) Granitoid magmas formed by the process of partial melting of the lower continental crust in the presence of hornblende, or derived by the process of fractional crystallization of quartz dioritic magmas with removal of hornblende. These are typified by the Jurassic granitoids of South Korea.

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