著者

吉谷 昭彦 山内 靖喜 小坂 哲朗 大西 郁夫

出版者

地学団体研究会

雑誌

地球科學 (ISSN:03666611)

巻号頁・発行日

vol.30, no.2, pp.95-101, 1976-03-20

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The Neogene and Quaternary volcanic activities in Shimane prefecture, western San'in district, are studied, and the results are summarized as follows. The Neogene volcanic activities are able to divide into two parts; are Green Tuff activities and Pliocene volcanic activities. The Green Tuff activities can be observed in the middle and lower Miocene strata, from Daishima to Onnagawa in stage. They are characterized by andesites and dacites activities, of being belong to hypersthenic rock series. However, pigeonitic basic andesites took place in earliest Daishima stage, and also alkaline olivine basalts in latest Onnagawa stage. The volcanic activities in Pliocene period are simply characterized by alkaline basalts activities. The Quaternary volcanic activities are composed of hypersthenic dacite and alkaline olivine basalts; the former is so-called "Daisen volcano system".