中国地方東部の二畳系とその変形

概要

論文の詳細を見る
Permian and Triassic strata are folded during the Middle Triassic Akiyoshi phase of orogeny in Chugoku region, the western Japan. Through careful analysis of geologic structures, it has been made clear that the Permian succession in Fig. 1. is kept almost constantly throughout the folded zone, although the thickness of strata varies from place. Folded structures of the Akiyoshi zone are summerrized in 6 cross sections of Fig. 3. It is build up of following 3 structural layers in ascending order: 1. Layer of crystalline schists and flow folding in the Lower Permian and beneath (Fig. 2, section 6; Pl. 1, Fig. 5; Pl. 2). 2. Layer of lense- and shear-folding in the Middle-Upper Permian and occasionally in the Lower Triassic (Pl. 1, Figs. 1, 2 & 4). 3. Layer of flexure folding in the Upper Permian and the Lower-Middle Triassic. Basic volcanic and pyroclastic rocks of the Lower Permianare metamorphosed into pumpellyite-prehnite-facies. The pile of "overburden" sediments above the metamorphosed rock including the Upper Permian to the Middle Triassic is estimated about 3 km in this region. If the depth is compared to the experimental pressure-condition of the metamorphic facies (WINKLER, 1967 etc.), the "tectonic over-pressure" for the metamorphism must be estimated twice as large as the overburden pressure. This folded zone is later, probably in the Cretaceous, faulted. In the Yanahara and the Omidani areas strike slip faults are provided with wide and distinct drag zones as shown in Fig. 2. Probably the same faulting is represented by the thrust in the Oga area, because the axis of the maximum principal stress is nearly the same in the two faultings. The thrust fault is produced in a shallow part of the crust, while the strike slip fault probably represents a deformation of the same crustal movement in the deeper crustal part than the thrust.
日本地質学会の論文
1971-07-31

中国地方東部の二畳系とその変形

スポンサーリンク

概要

著者

関連論文

スポンサーリンク