Geology of Oosima-gun,Yamaguti Prefecure.0n the Ryoke Metamorphic Rocks and Ryoke Grandiorites

山口県大島郡の地質と岩石一領家変成岩類ならびに花崗閃緑岩類

Geology of Oosima-gun,Yamaguti Prefecure.0n the Ryoke Metamorphic Rocks and Ryoke Grandiorites

Creators Okamura Yoshihiko

The Ryoke metamorphic zone in this area is composed of banded gneiss, hornfels of gneiss, migmatic gneissose granodiorite and intrusive granite. The granodiorite mass is divided as follws: 1.Gamano gneissic granodiorite. 2.0kiura gneissic granodiorite. 3. Towa granodiorite. 4. Fine grained granite (dike or sheet). The structural feature of the Gamano and the okiura granodiorite is their general comformity with the foliation and liniation of the banded gneiss,although cross-cutting pegmatite,aplite vein and dikes are common,and locally more homogeneous granodioritic part cross the schistosity. As the result of local contamination by xenolithic basic rocks, the Gamanogranodiorite may vary to tonalite or quartz diorite. The Gamano and the okiura granodiorite show many phenamena which can be cited as evidence that they originated through process of migmatization ofmetasediments. The Towa granodiorite and the fine grained granite are interpreted as form directly by consolidation of magma,

[ISSN]0513-1715

[NCID]AN00244250