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Sasao, Eiji
no journal, ,
Uranium deposits occur in various kinds of rocks at the earth's surface. Sedimentary rock has long been known to be particularly important as the host rock of economic uranium deposits. Source of uranium is generally considered to be basement granitic rock. Recent studies suggest that source of uranium may be released by decomposition of uranium-bearing heavy minerals and volcanic glass during diagenesis. This presentation is held in an invited speaker session regarding sedimentary rock. The author firstly introduces outline of uranium deposits occur in sedimentary rock and then discusses the relationship between uranium ore deposit, and sediment and diagenetic processes in some uranium deposits including the Tono uranium deposit as case examples.
Ishii, Eiichi
no journal, ,
no abstracts in English
Sasao, Eiji; Iwano, Hideki*; Danhara, Toru*; Hirata, Takafumi*
no journal, ,
The authors previously conducted Fission Track (FT) dating for tuff samples of the Miocene Mizunami and Iwamura groups in southeastern part of Gifu Prefecture, Central Japan. The determined depositional FT ages were, however, younger than their fossil ages for about one million years. To solve this issue, 
U-
Pb ages were determined using three of the tuff samples previously used for FT dating, also the FT age were recalculated based on the latest FT dating knowledge. As the result, U-Pb ages and recalculated FT ages coincided with each other within an acceptable error margin. Moreover, the obtained ages are concordant with fossil ages and magnetostratigraphic ages.
Yasue, Kenichi; Tokuyasu, Kayoko; Komatsu, Tetsuya; Horiuchi, Yasuharu; Shimizu, Mayuko; Niwa, Masakazu
no journal, ,
no abstracts in English
Ueki, Tadamasa; Niwa, Masakazu
no journal, ,
no abstracts in English
Shimizu, Mayuko; Sano, Naomi; Yasue, Kenichi; Shibata, Kenji*; Niwa, Masakazu; Suzuki, Kazuhiro
no journal, ,
no abstracts in English
Shimada, Koji; Sueoka, Shigeru; Ishimaru, Tsuneari
no journal, ,
The application of overlying sediments is one of the methods defining relative age based on the principle of cross-cutting relations. This principle is one of the geological principles indicating relative age of deformation features such as faulting or tectono-metamorphic textures. The application of overlying sediments and relative age determination of deformation features are also based on the principle of cross-cut relations. We present a method utilize relative deformation age by means of the cross-cut relations, temperature gauges shown by structures, and thermal history of geological body alternative to the application of overlying sediments. Research area is located near the FBR Monju. Data suggest that the activity of crush zones precede basaltic dyke formation under higher temperature environment. This research method is potential alternative, though case study is needed towards overcoming the unsuitable outcropping situation to grasp basic geological data.
Seshimo, Kazuyoshi; Aoki, Kazuhiro; Kametaka, Masao*; Nussbaum, C.*; Shimamoto, Toshihiko*; Ma, S.*; Yao, L.*
no journal, ,
no abstracts in English
Hatano, Nozomi*; Yoshida, Koki*; Sasao, Eiji; Kubota, Mitsuru; Adachi, Yoshiko*
no journal, ,
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.
Fukuda, Shoma*; Sueoka, Shigeru; Tagami, Takahiro*
no journal, ,
no abstracts in English