Abstract
At Ani Mine, Akita prefecture, the Tertiary intrusive body as some dykes on the surface and a stock form under the ground, of which diametre at the Taisho-ko level is about 4km from north to south and 1km east to west, has transitional variable facies that are divided as follows; diorite and granodiorite at the core, and fine grained diorite and porphyrite_??_andetsie or in part quartz porphyry_??_rhyolite at the margin. Porphyrite_??_randesite or quartz porphyry_??_rhyolite is a kind of the chilled margin of it. Namely, it varies in texture from holocrystalline to hyaline and in chemical composition intermediate to acidic. There is also arhyolite injecting it successively. The author calls them “Tertiary granitic rocks” in the lump.
The age of intrusion of Tertiary granitic rocks and the relations with the ore mineralization are discussed.
