長野県東筑摩地方北部の新第三系 : 特に込地向斜および野間背斜について

概要

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The area surveyed belongs to the northern part of the Fossa Magna region, and consists of the Middle Miocene to Middle Pliocene sediments with some intrusive and volcanic rocks. They are about 4,400 m in total thickness. This region implies both the folded and non-folded provinces of F. HOMMA (1931). The following results are obtained by the investigation of the present writer. 1. The Noma anticline is situated east of the Komiji syncline, and its axis extends from Naguki, Akashina Town to the western foot of Mt. Hijiri through Noma, Omi Village with a trend of slightly meandering N-S direction. 2. In this region a differential subsidence is inferred to have taken place after the Bessho stage. And the movement was accelerated especially after the Aoki stage. This is suggested by a remarkable difference in thickness and sedimentary structures between the western and eastern sides of the Noma anticline. The Noma anticline is located just along the boundary of these differentially subsiding areas, from which the folded and non-folded provinces have evolved. This differential subsidence is attributed probably to the block movement of the basement rocks. 3. From the result of geometrical considerations as to the three-dimensional shape of the Komiji syncline a cylindrical, concentric fold style is deduced to be most probable.
日本地質学会の論文
1976-12-30