奥能登柳田地方の地質
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概要
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This district consists of the Miocene (F_2-F_3) Minazuki formation together with various volcanic rocks such as hypersthene-augite andesite, bronzite andesite, olivine andesite, olivine basalt and dacite., Of these volcanic rocks, the olivine basalt belongs to the rock series of the Circum-Japan Sea Alkaline Rock Province, while the others belong to the rock series of the Cale Alkaline Rock Province as commonly found in Japan., It is interesting that these two rock series were erupted in the same period of volcanic activity and in the same limited area., The olivine basalt was erupted at the beginning of the deposition of the Minazuki formation of this district., The main activity which produced the hypersthene-augite andesite group seems to have nearly ceased with the end of the Anamizu stage and before the deposition of the afore-mentioned Minazuki formation., In the Minazuki stage pyroclastic and clastic sediments were mixed together in close connection with the volcanic activity., Accompanying the explosive eruption of dacite, enormous amounts of volcanic ash were deposited all over the district (the Ogi member)., These pyroclastic sediments reached a maximum thickness of more than 500m in the area east of this field, that is, near the center of the volcanic activity, and were partly eroded above or near sea level., Clastic materials produced by erosion of the andesite masses west of the district were deposited and intermingled with pyroclastic sediments in a complicated manner and show the marked influence of bottom currents.,
- 日本地質学会の論文
- 1953-11-25