Isotopic ages and strontium isotopic ratios of submarine rocks in the Japan Sea
1974 年 8 巻 4 号 p. 157-164
詳細
1974 年 8 巻 4 号 p. 157-164
One granodiorite, two basalts and five andesites dredged from seamounts and banks in the Japan Sea were studied by means of K-Ar and Rb-Sr dating methods. The granodiorite gives a concordant age of 227m.y, while the ages of the basalts and andesites range from 4 to 22m.y. The Sr isotopic ratios (87Sr/86Sr)0 of these samples are higher than the mean for island basalts.
