著者

竹越 智 赤松 陽 山田 誠一 杉山 明 清水 正明 木元 好一 佐瀬 和義 石橋 晃睦 久津間 文隆 桂 雄三 石垣 忍 本間 岳史 上野 一夫 滝田 良基 久家 直之 川畑 昭光 関根 勇蔵 藤井 克治

出版者

日本地質学会

雑誌

地質学論集 (ISSN:03858545)

巻号頁・発行日

no.13, pp.299-311, 1976-12-30

被引用文献数

3

---

The geology of the south-western region of the Tanzawa massif has remained unresearched except the horizons higher than the Pliocene series. After the writers' previous study on the geology of the crystalline schist region on the Tanzawa massif, the above mentioned area was surveyed. In this area the following formations are distributed; that is the Miocene series (so-called Misaka series) which consists largely of volcanic and pyroclastic rocks, the Pliocene series (the Ashigara group) of conglomerate and sandstone, the Pleistocene series (the Yufune formation or the Suruga gravel bed) of fluvial deposit, and the Alluvium of thick volcanic ash and river bed deposit. The Miocene series is divided, in ascending order, into the Kurokura formation, the Yozuku formation, the Hirayama formation and the Shirakurazawa member. The former three formations correspond to the westward extensions of those in the crystalline schist region, and they are superposed one upon the other conforrnably. They strike from NE to SW and dip northward, but are overturned. The Shirakurazawa member is distributed only in the surveyed area. Though it is contiguous to the Yozuku and the Hirayama formations with faults, it may be, judging from its lithofacies, the uppermost horizon of the Miocene series in this area. It strikes E-W and shows a synclinal structure as a whole. It is overturned near the northern marginal fault. The Kurokura formation and the lower part of the Yozuku formation are changed into crystalline schists with bedding schistosity. The fault, which separates the Miocene series from the Pliocene series, has been considered to be one continuous reverse fault and was named the Kannawa fault. But it may be a complex of two or three systems of fault judging from the phenomena observed at several very points and also from the geometry as a whole.