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Miyakawa, Kazuya; Nakata, Kotaro*; Kashiwaya, Koki*; Suwa, Yukiko*
no journal, ,
no abstracts in English
Dei, Shuntaro; Tachi, Yukio; Amano, Yuki; Francisco, P. C. M.; Sugiura, Yuki; Takahashi, Yoshio*
no journal, ,
no abstracts in English
Takeda, Masaki; Ono, Hirokazu
no journal, ,
no abstracts in English
Miyakawa, Kazuya; Kashiwaya, Koki*; Komura, Yuto*; Nakata, Kotaro*
no journal, ,
no abstracts in English
Sr isotopic analysis of apatite by LA-ICP-MS to constrain the chemical composition of the original magmaKagami, Saya; Yokoyama, Tatsunori; Sasao, Eiji; Yuguchi, Takashi*; Chang, Q.*
no journal, ,
The fracture frequency distribution in granitic plutons depends on lithofacies, which reflect the chemical composition of the original magma. The initial Sr isotopic ratio of the whole rock is a valid indicator to identify the chemical composition of the magma. The apatite Sr isotopic composition probably records a primary Sr isotopic composition of the original magma because Rb is incompatible element for apatite. In this study, we developed a method for in situ Sr isotopic analysis of apatite by LA-ICP-MS. We adopted the technique of introducing desolvated solutions and solid samples into the ICP mass spectrometer. The correction for mass discrimination effects in the solid sample analysis by LA was attempted based on the isotope analysis of the solution. A gas line for mixing N
into Ar sample carrier gas was installed to suppress the oxide production rate and improve the ionization efficiency of Sr. Our results of the analysis on the apatite reference materials were consistent with previous studies. In addition, we confirmed that this method can be applied to apatite samples with lower Sr mass fraction than above apatite reference materials and grain sizes of approximately 100 
m. The developed method enables the evaluation of differences in the chemical composition of the original magma and then provides the constraint on the relationship between lithofacies and fracture frequency distribution by combination with chemical and geological information of granitic rocks.
Ichikawa, Nozomi*; Hamamoto, Takafumi*; Sasamoto, Hiroshi; Ichige, Satoru*; Kawakita, Ryohei; Fujisaki, Kiyoshi*
no journal, ,
For model validation of bentonite behavior under high alkaline condition, a batch type reaction experiment and modeling were performed. In the batch type reaction experiment, simulated solutions for the leachate from cement material (Region I solution of pH13 simulated by mixture of both 0.2M NaOH and KOH solutions, Region II solution of pH12.5 simulated by 0.016M CaOH solution) and bentonite (Kunigel V1 and Kunipia F) were reacted under L/S ratio of 50 mL/g and temperature for either 25 or 50 degrees, and for 2 years as the maximum duration. As the results, for example of the experiment for reactions between Region I solution and Kunipia F at 50 degrees, the peak intensity for montmorillonite slightly decreased with time and the new formed secondary mineral suggested as phillipsite occur. Geochemical modeling for this experimental case was performed. Regarding the amount of montmorillonite dissolution, the modeling considering the reactions of both montmorillonite dissolution and ion exchange approximated the experimental result well, however, the addition of the secondary mineral precipitation reaction was less effective. Sensitivity analyses considering the parameter uncertainties of secondary mineral precipitation reaction stimulated that the inconsistency was not dependent on the parameter uncertainties.
Tanaka, Kazuya; Yamaji, Keiko*; Masuya, Hayato*; Tomita, Jumpei; Ozawa, Mayumi; Fukuyama, Kenjin*; Ohara, Yoshiyuki*; Kozai, Naofumi
no journal, ,
no abstracts in English
Yamaguchi, Akiko; Kurihara, Yuichi*; Nagata, Kojiro*; Kobayashi, Keita; Tanaka, Kazuya; Kobayashi, Toru; Tanida, Hajime; Yaita, Tsuyoshi; Yoshimura, Takashi*; Okumura, Masahiko; et al.
no journal, ,
no abstracts in English