Petrology of the tabashine granitic body, Kitakami mountains, northeastern Japan.

Abstract

To reveal the chemical characters of the Tabashine granitic body, southern Kitakami mountains, thirteen rocks, ten biotites and seven hornblendes were analysed chemically. As a result, the analyses indicate high K2O in rocks, high TiO2 in biotites, and low Al2O3 in both biotites and hornblendes. These chemical features of the Tabashine body are common to the Orikabe and Hirota, while the other adjacent granites called Senmaya, Hitokabe and Kesengawa are different. Judging from the fact that all rock types of the Tabashine body, i. e. gabbroic, granodioritic and adamellitic rocks, show similar features of mineral chemistry, it is considered that they are comagmatic dervatives. On the other hand, the reason why the rocks of the three bodies, Tabashine, Orikabe and Hirota, show similar features and are different from the other adjacent granites of Senmaya, Hitokabe and Kesengawa, is probably that their magmas had the same origin and had been passed under similar physicochemical conditions.