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

研究了九州西南部的四万十带和德之岛的地质构造。在北佐地区，玄武质熔岩、燧石和泥岩层形成叠瓦状结构。萨摩半岛的八谷地区是四万十带蛇纹岩的产状之一。在约100 x 50 m和200 x 70 m的区域内出露两个主要蛇纹岩体。它们覆盖在具有近水平边界的砂岩和泥岩的西倾层上。在南萨苏地区的Choyasan区域，泥岩和砂岩层通常向西倾斜，并向西倾斜。德之岛中部的地质由泥砂质片岩、花岗质侵入岩和零星的蛇纹岩组成。泥质片岩中分布有低角度北西倾的蛇纹岩透镜体。在德之岛西部的秋上川河口的泥质和砂质片岩中，出现了厚度达20 cm的暗色脉。大小不一的围岩碎片和细粒填充在矿脉中。

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.