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PdSi
Hirschberger, M.*; Nakajima, Taro*; Kriener, M.*; Kurumaji, Takashi*; Spitz, L.*; Gao, S.*; Kikkawa, Akiko*; Yamasaki, Yuichi*; Sagayama, Hajime*; Nakao, Hironori*; et al.
Physical Review B, 101(22), p.220401_1 - 220401_6, 2020/06
Times Cited Count：40 Percentile：91.78(Materials Science, Multidisciplinary)Yamasaki, Seiko*; Zwingmann, H.*; Yamada, Kunimi*; Tagami, Takahiro*; Umeda, Koji
Chemical Geology, 351, p.168 - 174, 2013/08
Times Cited Count：25 Percentile：60.27(Geochemistry & Geophysics)Constraining of the timing of fault zone formation is of fundamental geotectonic importance to understand structural evolution and brittle fault processes. Here, we present authigenic illite K-Ar age data from brittle fault zones comprising two gouges within the Toki granite, central Japan. The gouge samples were collected from a shaft at the Mizunami Underground Research Laboratory, and were separated into five grain-size fractions. K-Ar ages of clay fractions decrease with grain size, suggesting enrichment in finer fraction of more-recently grown authigenic illites. The K-Ar ages of the fractions range from 53.6 to 42.7 Ma (Paleogene-Early to Middle Eocene). The 
0.1 
m fractions yield ages of 42.7 and 46.5 Ma. This age range is consistent with the stability field of illite and the main temperature field of brittle deformation within the cooling history of the Toki granite, supported by extensive thermochronological data of the host rock.
Yamasaki, Seiko; Umeda, Koji
Ganseki Kobutsu Kagaku, 41(2), p.39 - 46, 2012/05
The thermal history of the Toki granite body exposed in the eastern Sanyo Belt, Central Japan, was evaluated from various chronological data by K-Ar, fission track methods and Rb-Sr. The K-Ar ages obtained from biotite ranged from 72 to 74 Ma, which were concordant with the K-Ar ages of hornblende and the reported Rb-Sr whole-rock isochron ages. Fission-track ages for zircon and apatite in the Toki granite were 64 to 73 Ma and 37 to 40 Ma, respectively. These thermochronological data revealed two distinctive cooling stages for the Cretaceous Toki granite; (1) a rapid cooling stage which the granitic magma was cooled to the temperature of host rock soon after intrusion at depths of 5 - 6 km in the upper crust, and (2) the subsequent slow cooling stage (7 - 10 
C/m.y.) associated with the exhumation of the granite body after ca. 60 Ma.
Yasue, Kenichi; Asamori, Koichi; Tanikawa, Shinichi; Yamada, Kunimi; Yamasaki, Seiko; Kokubu, Yoko; Niwa, Masakazu; Doke, Ryosuke; Kusano, Tomohiro; Hanamuro, Takahiro; et al.
JAEA-Research 2011-023, 113 Pages, 2011/10
JAEA-Research-2011-023.pdf:10.9MB
This annual report documents the progress of R&D in the first fiscal year during the JAEA 2nd Midterm Plan (FY 2010 - 2014) to provide the scientific base for assessing geosphere stability for long-term isolation of the high-level radioactive waste. The planed framework is structured into the following categories: (1) development and systematization of investigation techniques for selecting suitable sites in geosphere stability, (2) development, application and verification of prediction models for evaluating the changes of geological environment in thermal, hydraulic, mechanical and geochemical conditions for a long period of time, and (3) development of new dating techniques for providing information about geologic history and the timing of geologic events. In this paper, the current status of R&D activities with previous scientific and technological progress is summarized.
Yasue, Kenichi; Asamori, Koichi; Kusano, Tomohiro; Kokubu, Yoko; Tanikawa, Shinichi; Niwa, Masakazu; Hanamuro, Takahiro; Yamasaki, Seiko; Yamada, Kunimi; Ishimaru, Tsuneari; et al.
JAEA-Review 2011-023, 43 Pages, 2011/07
JAEA-Review-2011-023.pdf:1.84MB
The concept of geological disposal of HLW in Japan is based on a multibarrier system which combines a stable geological environment with an engineered barrier system. Potential geological host formations and their surroundings are chosen, in particular, for their long-term stability, taking into account the fact that Japan is located in a tectonically active zone. This report is a plan of research and development (R&D) for geosphere stability for long-term isolation of HLW in JAEA, in fiscal year 2011. The objectives and contents in fiscal year 2011 are described in detail based on the outline of 5 years plan (fiscal years 2010-2014). In addition, the plan framework is structured into the following categories: (1) Development and systematization of investigation techniques, (2) Development of models for long-term estimation and effective assessment, (3) Development of dating techniques.
Kusano, Tomohiro; Asamori, Koichi; Kurosawa, Hideki; Kokubu, Yoko; Tanikawa, Shinichi; Negi, Tateyuki; Hanamuro, Takahiro; Yasue, Kenichi; Yamasaki, Seiko; Yamada, Kunimi; et al.
JAEA-Research 2010-044, 153 Pages, 2011/01
JAEA-Research-2010-044.pdf:12.53MB
This progress report (H22 report) documents progress made during JAEA 1st Midterm Plan (FY 2005 - 2009) to provide the scientific base for assessing geosphere stability for long-term isolation of the high-level radioactive waste. For the current 5-year R&D programme, three major goals have been defined as follows: (1) development and synthesis of investigation techniques for selecting suitable sites in geosphere stability, (2) development, application, and evaluation of prediction models for evaluating the changes of geological environment in thermal, hydraulic, mechanical and geochemical conditions for a long period of time, and (3) development of new dating techniques for providing information about geologic history and the timing of geologic events. In this paper, the current status of R&D activities with previous scientific and technological progress is summarized.
Yasue, Kenichi; Asamori, Koichi; Yamada, Kunimi; Kokubu, Yoko; Yamasaki, Seiko; Kurosawa, Hideki; Tanikawa, Shinichi; Negi, Tateyuki; Kusano, Tomohiro; Hanamuro, Takahiro; et al.
JAEA-Review 2010-034, 42 Pages, 2010/09
JAEA-Review-2010-034.pdf:1.15MB
The concept of geological disposal of HLW in Japan is based on a multibarrier system which combines a stable geological environment with an engineered barrier system. Potential geological host formations and their surroundings are chosen, in particular, for their long-term stability, taking into account the fact that Japan is located in a tectonically active zone. This report is a plan of research and development (R&D) for geosphere stability for long-term isolation of HLW in JAEA, in fiscal year 2010. The objectives and contents in fiscal year 2010 are described in detail based on the outline of 5 years plan (fiscal years 2010-2014). In addition, the plan framework is structured into the following categories: (1) Development and systematization of investigation techniques, (2) Development of models for long-term estimation and effective assessment, (3) Development of dating techniques.
Yamada, Kunimi; Yamasaki, Seiko
no journal, ,
no abstracts in English
Yamasaki, Seiko; Yamada, Kunimi; Hanamuro, Takahiro; Umeda, Koji; Tagami, Takahiro*
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no abstracts in English
Yamasaki, Seiko; Yamada, Kunimi; Umeda, Koji; Hanamuro, Takahiro; Tagami, Takahiro*
no journal, ,
no abstracts in English
Yamada, Kunimi; Hanamuro, Takahiro; Yamasaki, Seiko
no journal, ,
no abstracts in English
Yamasaki, Seiko; Yamada, Kunimi; Tagami, Takahiro*; Zwingmann, H.*
no journal, ,
no abstracts in English
Yamasaki, Seiko; Yamada, Kunimi; Tagami, Takahiro*; Zwingmann, H.*
no journal, ,
no abstracts in English
Yamasaki, Seiko; Zwingmann, H.*; Todd, A.*; Yamada, Kunimi; Umeda, Koji; Tagami, Takahiro*
no journal, ,
Early studies highlighted the potential for determining the timing of brittle fault deformation using isotopic dating of authigenic illites in fault gouge. However, it has remained difficult owing to the possibility of contamination of detrital material. In recent years, precise size separation combined with mineral characterization of the gouge samples has demonstrated the suitability of illite K-Ar dating for constraining the timing of brittle deformation, but further investigation on various geological setting is needed. In this study, we present K-Ar age data from two gouge samples collected from the fault in the Cretaceous Toki granite, central Japan. The gouge samples were separated into four grain-size fractions and characterized by XRD, SEM, and TEM. The fine fractions give younger K-Ar ages, suggesting enrichment in more recently grown authigenic illites. The K-Ar ages of the fractions with no detectable contamination from detrital K-bearing minerals on XRD analysis range from 53 to 43 Ma. This age is consistent with the stability field of illite and the main temperature field of brittle deformation within the cooling history of Toki granite body, which was evaluated by the ages from the hostrock.
Yamada, Kunimi; Yamasaki, Seiko
no journal, ,
no abstracts in English
Yamada, Kunimi; Yamasaki, Seiko
no journal, ,
no abstracts in English
Niwa, Masakazu; Kokubu, Yoko; Hanamuro, Takahiro; Matsubara, Akihiro; Yamasaki, Seiko*
no journal, ,
We report R&D process of 
Be dating for a calculation of upheaval and denudation rates, and K-Ar dating for an assessment of fault activity.
