Petrology of andesites from the Yamato central rise,Sea of Japan

The composition of andesites from the Yamato central submarine rise and adjacent structures (Sea of Japan) points to the presence of a Late Cretaceous shortened and Oligocene-Miocene extended calc-alkaline series. With the general similarity of mineral assemblages of andesites, they are distinct in composition of minerals, which testifies to different formation conditions. The andesites of the extended type are the products of crystallization differentiation, whereas those of the shortened type are characterized by nonequilibrium composition of minerals, which reflects the heterogeneous primary melt, the composition of which discretely varied (probably repeatedly) during crystallization.