[S-GL23] Geologic structure and tectonic history of East Asia and Japanese Islands

[SGL23-P03] Geologic structure of the Jurassic accretionary complexes in the Ashio Mountains, based on the geologic survey of the Kanuma area

*Ito Tsuyoshi¹ (1.Geological Survey of Japan, AIST)

Keywords:Ashio Belt, Jurassic, radiolarian, geologic structure

Jurassic accretionary complexes of the Ashio Belt are distributed in the Ashio Mountains in central Japan. Although many studies have been conducted around the Tochigi area in the southeastern part of the Ashio Mountains, there are only a few studies in other areas, especially in the Kanuma area in the northeastern mountains.
I have conducted a geological survey in the Kanuma area. The Kanma Fault, which has been recognized in the southwestern part of the Ashio Mountains, was found to extend into the Kanuma area. By the Kanma Fault, the Kuzu Complex is located in the southeastern part of the Kanuma area, and the Kurohone–Kiryu Complex is located in the northwestern part of the area.
In previous studies, the Jurassic accretionary complex in the Ashio Mountains was considered to contain large-scale folds. The present results suggest a major structure on the northwest side of the Kanma Fault consisting of the Kurohone–Kiryu Complex and the Omama Complex in structurally ascending order; and on the southeast side consisting of the Kuzu Complex and the Gyodosan Complex in structurally ascending order.