Initialising ...
Initialising ...
Initialising ...
Initialising ...
Initialising ...
Initialising ...
Initialising ...
Yuguchi, Takashi*; Ito, Daichi*; Yokoyama, Tatsunori; Sakata, Shuhei*; Suzuki, Satoshi*; Ogita, Yasuhiro; Yagi, Koshi*; Imura, Takumi*; Motai, Satoko*; Ono, Takeshi*
Lithos, 440-441, p.107026_1 - 107026_14, 2023/03
Times Cited Count：0 Percentile：0.02(Geochemistry & Geophysics)We propose a new method for elucidating zircon growth in granitic plutons, based on variations in three-dimensional 3D cathodoluminescence (CL) patterns, U-Pb ages, titanium concentration, and Th/U ratios. We focused on the zircon growth processes in the Okueyama granite (OKG) in central Kyushu, Japan, to obtain interpretations of magma chamber processes that result in the formation of granitic plutons. The OKG consists of three lithofacies: biotite granite (BG), hornblende granite (HG), and hornblende granodiorite (HGD). To determine the 3D internal structure and growth pattern of a zircon crystal, we performed CL observations for multi-sections of the samples. Simultaneously, we also determined the zircon U-Pb age and titanium concentration of the center sections of the samples. The 3D distribution of the oscillatory zoning can be used to determine the crystal nucleus. The simultaneous determination of zircon U-Pb ages and Ti concentrations of the granite samples indicates the time-temperature (t-T) history of granitic magma before its solidification. The t-T histories of the BG, HG, and HGD represented similar cooling behaviors within the magma chamber: rapid cooling from the zircon crystallization temperature to the closure temperature of the biotite K-Ar system between 16 Ma and 10 Ma. The variations in the Th/U ratios against temperature also demonstrate a different trend at the boundary of approximately 670 
C. Fractional crystallization in the magma chamber progressed significantly at temperatures above 670 C; below 670 C, crystallization progressed slowly, indicating only minimal changes in the magma composition. The variations in the Th/U ratio against temperature in the BG, HG, and HGD portrayed common tendencies, indicating the same behavior in the progression of fractional crystallization among the three lithofacies, which in turn, represented the same behavior within the entire magma chamber.
Kitagaki, Toru; Yoshida, Kenta*; Liu, P.*; Shobu, Takahisa
npj Materials Degradation (Internet), 6(1), p.13_1 - 13_8, 2022/02
Times Cited Count：1 Percentile：14.66(Materials Science, Multidisciplinary)Kitagaki, Toru
Journal of Nuclear Materials, 557, p.153254_1 - 153254_8, 2021/12
Times Cited Count：1 Percentile：16.35(Materials Science, Multidisciplinary)
-edge XANES to determination of U oxidation state in zirconTanaka, Kazuya; Takahashi, Yoshio*
Geochemical Journal, 53(5), p.329 - 331, 2019/00
Times Cited Count：0 Percentile：0.01(Geochemistry & Geophysics)We examined three natural zircon samples with different amounts of radiation doses using M-edge and L
-edge U X-ray absorption near-edge structure (XANES). Analysis of XANES spectra at both M-edge and L-edge suggested that the oxidation state of U in the zircon sample with the highest radiation dose is tetravalent. The XANES spectra of the two other samples with lower radiation doses suggested a mixture of U(IV) and U(VI), while the possibility of U(V) was not excluded. This is the first work on the application of M-edge U XANES to the oxidation state of U in natural zircon.
Egusa, Shigenori; *
Ferroelectrics, 145, p.45 - 60, 1993/00
no abstracts in English
Egusa, Shigenori; *
J. Mater. Sci., 28, p.1667 - 1672, 1993/00
Times Cited Count：60 Percentile：90.55(Materials Science, Multidisciplinary)no abstracts in English
Egusa, Shigenori; *
Proc. of the 7th Int. Conf. on Solid-state Sensors and Actuators, p.976 - 979, 1993/00
no abstracts in English
Murakami, Takashi; B.C.Chakoumakos*; R.C.Ewing*; G.R.Lumpkin*; W.J.Weber*
American Mineralogist, 76, p.1510 - 1532, 1991/00
no abstracts in English
B.C.Chakoumakos*; Murakami, Takashi; G.R.Lumpkin*; R.C.Ewing*
Science, 236, p.1556 - 1559, 1987/00
Times Cited Count：177 Percentile：96.97(Multidisciplinary Sciences)no abstracts in English
*; ; *
Nihon Kagaku Zasshi, 82(9), P. 1156, 1961/00
no abstracts in English
Ueki, Tadamasa; Shimizu, Mayuko; Sano, Naomi; Yonaga, Yusuke
no journal, ,
no abstracts in English
Ueki, Tadamasa; Niwa, Masakazu; Yonaga, Yusuke
no journal, ,
no abstracts in English
Ueki, Tadamasa; Niwa, Masakazu; Yonaga, Yusuke; Iwano, Hideki*; Danhara, Toru*
no journal, ,
no abstracts in English
Ueki, Tadamasa; Yokoyama, Tatsunori
no journal, ,
no abstracts in English
Kitagaki, Toru
no journal, ,
no abstracts in English
Kitagaki, Toru; Horie, Kenji*; Takehara, Mami*; Onuki, Toshihiko*
no journal, ,
Estimation method of environmental condition changes in molten pool generated by Molten Core Concrete Interaction (MCCI) during Fukushima Daiichi NPP accident by analyzing zircon has been developping. In this research, simulant MCCI product without uranium was made under various conditions, zircon formation behavior was confirmed.
Kitagaki, Toru; Yoshida, Kenta*; Suzuki, Tatsuya*
no journal, ,
In order to estimate the physical/chemical properties of the fuel debris remaining in 1F, it is important to estimate the environmental conditions in 1F, such as temperature or oxygen potential during Molten Core-Concrete Interaction (MCCI) in the molten pools. To this end, this study focuses on the degradation behavior of zircon minerals in different solution conditions were investigated. The SEM results indicate that needle-like crystals were formed on the zircon surface as a secondary product only when the mineral was soaked in aqueous NaOH. The relevant crystal structure was further confirmed with TEM.
Kitagaki, Toru; Ikeda, Atsushi
no journal, ,
Large amounts of fuel debris are expected to be accumulated under the cooling water in the containment vessel of 1F. Parts of them could be leached and dispersed into the water. Therefore, the leaching behavior of fuel debris should be estimated. However, it is difficult to evaluate the leaching rate by traditional methods, such as solution analysis, because fuel debris is multiphase and heterogeneous materials. On the other hands, in-situ observation methods such as interferometric microscope can measure leaching rate by surface shape change. Zircon, ZrSiO
, is expected to be one of the main phases in 1F fuel debris. In this study, an interferometric microscope was applied to the measurement of the leaching rate of natural zircon under the flowing aqueous solutions with pH = 0 (HCl), 7 (ultrapure water), and 14 (aq NaOH) based on the change of zircon surface. It was confirmed that the dissolution rates under different aqueous solution can be measured by the applied method.
Fukuda, Shoma
no journal, ,
The (U-Th)/He thermochronometer is a method used to estimate the age based on the alpha decay of U and Th series in mineral crystals with U and Th concentrations as the parent isotopes and He-4 content as the daughter isotope. This method is utilized for dating within 0.1 to 100 Myr timescales. Its low closure temperature allows for reconstruction of geoscientific phenomena such as uplift/erosion in mountains, fault movements, and volcanism and magmatism. Regarding zircon (U-Th)/He (hereinafter, ZHe) method, the Fish Canyon Tuff zircon (a standard of zircon fission-track method) has been employed empirically as a reference material. However, some of these zircons have yielded heterogeneous U-Th distributions. Therefore, new potential zircons for (U-Th)/He dating are desirable. In this study, we conducted ZHe dating on eight zircons from potential samples collected in Japan and other age standards, and evaluated the consistency, age dispersions and their factor. Consequently, the Utaosa rhyolite (TRG04) and Mt. Dromedary (a zircon fission-track age standard) have the potential as reference materials in the ZHe method. As future prospect, we plan to conduct a round-robin test for inter-laboratory comparison.
