So-colled Tertiary Granites, intruded at Miocene age as the form of stock or dyke in northeastern Japan can be characterized as follows;
1) The intrusive bodies have variable facies respectively. They change in texture from holocrystalline to hyaline. Many of them vary their chemical compositions from intermediate to acidic, and a few from basic through intermediate to acidic.
2) Alterations such as chloritization, albitization, sericitization, carbonitization, epidotization and pyritization of the body are seen remarkably even if any mineralization is not observed in the body. These alterations are observed more distinctly in the marginal part of it.
3) Gold bering chalcopyrite•galena•sphalerite deposits are seen in connection with the Tertiary Granites. There are some examples of veins which might be formed under the xenothermal condition.
In this paper, some problems concering these characteristics are presented. The author suggests that it had better regard the intrusive body as a complex derived from volcano-plutonism.
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