著者

松川 正樹 平野 弘道 野田 雅之 水野 篤行 二上 政夫 利光 誠一 長谷川 卓

出版者

一般社団法人 日本地質学会

雑誌

地質學雜誌 (ISSN:00167630)

巻号頁・発行日

vol.101, no.1, pp.V-VI, 1995-01-15

参考文献数

3

著者

水野 篤行 片田 正人

出版者

地学団体研究会

雑誌

地球科学 (ISSN:03666611)

巻号頁・発行日

vol.1958, no.39, pp.1-14, 1958-08-28 (Released:2017-07-24)

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The lithological and structural features of the Nishiyatsushiro group in the northwestern area of Southern Fossa Magna are clarified in this paper. 1) The Nishiyatsushiro group, overlain by the Shizukawa and Nishikatsura groups, of upper Miocene or lower Pliocene, comprises 7 formations and 24 members. It is divided into 4 parts, namely, the lower, middle, upper and uppermost parts, each having its own characteristic sedimentary facies and products of igneous activities. 2) The lower part (more than 800m. in thickness) is characterized by a large quantity of basalt and andesite lavas with their pyroclastics; the middle (600 to 4,000m. in thickness) by mudstone with dacite pyroclastics and basalt lavas, the last of which comprises alkaline rocks ; the upper (500 to 3,000m. in thickness) by dacitic rocks and coarse clastic rocks, in which Lepidocyclinabearing limestone beds are intercalated; and the uppermost (more than 1,200m, in thickness) by various clastic rocks, 3) The group is assigned to middle-early Miocene in geologic age. 4) The tectonic movement in the area took place after and also during the formation of the Nishiyatsushiro group, probably with the intrusion of quartz diorite.