<国立科博専報>赤石山地と紀伊半島の四万十帯 : とくに砂岩の鉱物組成の考察

概要

論文の詳細を見る
The Shimanto Terrain in the Outer Zone of Southwest Japan was a geosynclinalarea throughout the late Mesozoic to early Neogene. In the present paper the recent progress on the study of the Shimanto Terrain in the Akaishi Mountainland and the Kii Peninsula is reviewed briefl and the result of petrographic analysis of massive and/or thick-bedded sandstones in the former area is reported. The Shimanto Terrain south or the Butsuzo Tectonic Line is divided into inner Cretaceous belt and outer Paleogene belt. Generally speaking sandstones in the Cretaceous belt are characterized by containing abundant acid volcanic rock-fragments, whereas those in the Paleogene belt are characterized by high quartz-content. Potash-feldspars are usually found in most sandstones, although there exist some exclusive ones free from them. From the view point of sandstone petrography it is inferred that the Shimanto geosyncline cannot be assigned as the site of plate subduction.
国立科学博物館の論文