大雨見山層群の地質 : 飛騨外縁帯における白亜紀末期酸性火山作用

概要

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The Oamamiyama Group is one of the volcanic piles of the Late Cretaceous age, covering about 100 Km^2 in the Hida Marginal Belt, and composed chiefly of silicic pyroclastic flow deposits with lacustrine deposits in the lower part. Stratigraphic succession of this group in the studied area is as follows: [Table] Basement Rocks (Paleozoic sediments, Funatsu Granitic Rocks and Tetori Group) Many palynomorphs from the Miyadanigawa Formation indicate that this formation is of the Maestrichtian (The Latest Cretaceous) age. The Oamamiyama Group overlies the basement rocks, with high-angle unconformityin many places, and frequently the ill-sorted breccias occur between them. These breccias are probably paleo-talus deposites, judging from their distribution and lithofacies, and suggest that the depression took place on the basement rocks prior to the deposition of pyroclastic rocks. Sankyunotaki Rhyolite and Tonomura Rhyodacite Welded Tuff, which occupy the upper parts of Miyadanigawa Formation, cover the Miyadanigawa and its adjacent areas, while Akegatani Rhyolite Welded Tuff is widely distributed over the studied area. The Oamamiyama Group, in the eastern part of this area, suffered from contact metamorphism due to Gomihara Granophyre mass.
日本地質学会の論文
1979-09-20