17:15 〜 18:30
[MIS13-P05] ペルム系芳井層群の遠洋成チャートにみられる砂岩岩脈とその変形構造
キーワード：延性変形、ペルム紀、放散虫、遠洋成チャート、砂岩岩脈、秋吉テレーン
Deformation structure of consolidated cherts would record its diagenetic process. The Akiyoshi terrane, which is a Permian accretionary complex of the Inner Zone of Southwest Japan, contains Permian cherts. However, there are a few studies that have described the deformation structure of the Permian cherts of the Akiyoshi terrane. The Yoshii Group, distributed over west Okayama Prefecture, belongs to the Akiyoshi terrane.
We discovered ductilely- and brittlely-deformed chert blocks within sandstone dikes of the Yoshii Group in the Mihara area. The ductilely-deformed chert blocks and the clay minerals within the sandstone dikes are elongated and have slightly preferred orientation.
Pseudoalbaillella sp. cf. P. longtanensis Sheng et Wang was obtained from a chert bed just below the sandstone dike. Pseudoalbaillella longtanensis is characteristic species of the P. longtanensis Assemblage-Zone corresponding tentatively to the Kungurian (Cisuralian: Lower Permian).
The presence of the ductilely-deformed cherts suggests that the siliceous deposits had yet been unconsolidated when the sandstone dikes intruded. The sandstone dikes might be originated in terrigenous clastic, which is a component of chert-clastic sequences of the Yoshii Group in the Mihara area. The Permian chert had kept unconsolidated more than 10 My in this case.
We discovered ductilely- and brittlely-deformed chert blocks within sandstone dikes of the Yoshii Group in the Mihara area. The ductilely-deformed chert blocks and the clay minerals within the sandstone dikes are elongated and have slightly preferred orientation.
Pseudoalbaillella sp. cf. P. longtanensis Sheng et Wang was obtained from a chert bed just below the sandstone dike. Pseudoalbaillella longtanensis is characteristic species of the P. longtanensis Assemblage-Zone corresponding tentatively to the Kungurian (Cisuralian: Lower Permian).
The presence of the ductilely-deformed cherts suggests that the siliceous deposits had yet been unconsolidated when the sandstone dikes intruded. The sandstone dikes might be originated in terrigenous clastic, which is a component of chert-clastic sequences of the Yoshii Group in the Mihara area. The Permian chert had kept unconsolidated more than 10 My in this case.