Untitled research work

Sixteen trace elements, Co, Cr, Sc, Ba, Hf, Th, La, Ce, Sm, Eu, Tb, Yb, Lu, Rb, Cs and Ta, in the late Cretaceous_??_Paleogene granitic rocks were analyzed by instrumental neutron activation technique for 64 samples collected from Chugoku district, southwestern Japan. SiO2, Rb and Sr were determined by X-ray fluorescence method. The analytical results were shown in Table 1, and the average trace element contents in the granitic rocks were calculated as shown in the first column of Table 2. The late Cretaceous_??_Paleogene granitic rocks of Chugoku district have 2 or 3 times higher Th content compared with the Quaternary calc-alkaline volcanic rocks of northeastern Japan.