Areal comparison of the geochemistry of the Todo Porcelain Clay Formation; For reconstruction of paleo-weathering condition in the Neogene period

Hatano, Nozomi*; Yoshida, Koki*; Sasao, Eiji   ; Kubota, Mitsuru; Adachi, Yoshiko*

Weathered zone is located between earth surface and geological environment. Understanding of weathered zone is important for safety assessment of HLW geological disposal. Porcelain clay formation, distributed in southeastern Gifu and eastern Aichi prefectures, consists of fine-grained sediment derived from strongly weathered granite. Discussion on relationship between topographic and weathering conditions of basement rock and porcelain clay is needed to understand paleo-environment when porcelain clay was formed. The authors investigate chemical and mineral composition of porcelain clay. Mineral composition varies considerably with location. Si content of porcelain clay is significantly higher than basement rock and PAAS which represents average chemical composition of crust. The result suggests that chemical composition of host rock was altered by strong weathering. Variation of Ti content with location is possibly caused by topographic and weathering condition of provenance.