S3：東アジアのテクトニクス （スペシャルセッション）

[S3-03] Tonoshiki breccia recording the signature of the closure of Maizuru back-arc basin during Permian-Triassic boundary

*Larissa NGOMBI MAVOUNGOU¹, Kaushik DAS^1,2, Yasutaka HAYASAKA^1,2, Kenta KAWAGUCHI³, Jun-ichi ANDO^1,2 (1. Hiroshima Univ. Sci., 2. HIPER, 3. Jeonbuk Nat. Univ., Korea)

キーワード：Basin closure, Hydraulic fracturing, Late Permian, Maizuru back-arc basin, Tonoshiki breccia

Tonoshiki Fm is a breccia-dominated unit which was deposited during Maizuru back-arc basin closure. Two types of breccia are identified with different petrological, geochronological, and microstructural features. They show Latest Permian depositional ages of 259 and 251 Ma, implying its formation during two events of tectonic activity-induced debris flows. Network of fracture-filled veins in the breccia provides evidence of hydraulic fracture representing the tectonic signature of basin closure.