鈴鹿・養老両山系間の鮮新・更新統東海層群 : 東海湖終息期の堆積物

概要

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The upper to uppermost sediments of the Tokai Group are distributed between the Suzuka and Yoro Mountains. The geology of the Tokai Group in this area is summarized as follows: 1. The Tokai Group attaining to 950 m thick is divided into the Biroku (composed of gravel), Kono (mud and sand), Ichinohara (gravel and mud), Ohizumi (mud and sand), Tara (gravel and mud) and Komeno (gravel) Formations in ascending order. Among them, the Ohizumi and Tara Formations interfinger. The sediments of the Ichinohara, Tara and Ohizumi Formations are gradually finer southward. 2. In general, the Tokai Group dips 10-20° to the west, and strikes parallel to the piedmont lines of the Suzuka and Yoro Mountains. 3. The Tokai Group yielded Stegodon akashiensis from three localities, and their horizons have been revealed to be restricted to the Ohizumi and (lower part of) Tara Formations. 4. The depocenter in the Tokai Group shifted northward, and the accumulation of the Tokai Sedimentary Basin finished during the period ranging from 0.90 Ma to 0.70 Ma with the deposition of the Komeno Formation. 5. The sediment source areas are inferred as follows: (a) The Biroku Formation was supplied from the Yoro Mountains, (b) the Ichinohara, Tara and Ohizumi Formations were transported from about 50 km northern area beyond the Yoro Mountains, and (c) the Komeno Formation was supplied from the Suzuka Mountains.
1988-01-25