Precise structural analysis of the Shimanto accretionary complex in Kyushu, southwest Japan.

点击翻译按钮获取中文摘要

Geological structures of the Shimanto Belt in southwestern Kyusyu and Tokunoshima Island have been investigated. In the Hokusatsu district, layers of basaltic lava, chert and mudstone form imbricate structure. The Yaseo area in the Satsuma Peninsula carries one of the serpentinite occurrences in the Shimanto Belt. Two majorserpentinite bodies are exposed in the areas extending about 100 x 50 m and 200 x 70 m.These overlie west-dipping layers of sandstone and mudstone with subhorizontal boundaries.In the Choyasan area of the Nansatsu district, layers of mudstone and sandstone generally dip west with westerly younging. Geology of the central part of Tokunoshima Island is composed of pelitic-psammitic schsits, granitic intrusive rocks and sporadic serpentinite. Lenticular bodies of serpentinite dipping northwest in low angles are distributed in the pelitic schist. Dark-shaded veins with up to 20 cm thick appearin the pelitic and psammitic schists at the mouth of Akirigami River in western Tokunoshima. Fragments of the country rocks in variable sizes and fine-grained particles fill the veins.