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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:2 Percentile:23.81(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.
Yuguchi, Takashi*; Ishibashi, Kozue*; Sakata, Shuhei*; Yokoyama, Tatsunori; Ito, Daichi*; Ogita, Yasuhiro; Yagi, Koshi*; Ono, Takeshi*
Lithos, 372-373, p.105682_1 - 105682_9, 2020/11
Times Cited Count:7 Percentile:34.03(Geochemistry & Geophysics)Simultaneous determination of zircon U-Pb age and titanium concentration for a single analysis spot gives both the crystallization age and temperature. The crystallization age and temperature pairs in granitic zircons map the time-temperature () path of granitic magma before its solidification. In laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS) analysis, it is challenging to quantitatively analyse a low level of titanium concentration. This study employed two approaches using a Quadrupole mass spectrometer equipped with a collision/reaction cell (CRC). The methods were applied to zircon samples of the Kurobegawa granite (KRG), the Okueyama granite (OKG), the Toki granite (TKG), and the Tono plutonic complex (TPC) and provided U-Pb ages and titanium concentrations consistent with previous studies. The crystallization ages and temperatures collected from individual analysis spots of zircon samples in the KRG, OKG, TKG, and TPC are plotted in the
diagrams and enable us to characterize the rapid cooling paths at thermal conditions of zircon crystallization at the sampling sites.
Iizuka, Riko*; Kagi, Hiroyuki*; Komatsu, Kazuki*; Ushijima, Daichi*; Nakano, Satoshi*; Sano, Asami; Nagai, Takaya*; Yagi, Takehiko*
Physics and Chemistry of Minerals, 38(10), p.777 - 785, 2011/12
Times Cited Count:11 Percentile:34.76(Materials Science, Multidisciplinary)The pressure responses of portlandite and the isotope effect on the phase transition were investigated at room temperature from single-crystal Raman and IR spectra and from powder X-ray diffraction using diamond anvil cells under quasi-hydrostatic conditions in a helium pressure-transmitting medium. Phase transformation and subsequent peak broadening observed from the Raman and IR spectra of Ca(OH) occurred at lower pressures than those of Ca(OD)
. In contrast, no isotope effect was found on the volume and axial compressions observed from powder X-ray diffraction patterns. X-ray diffraction lines attributable to the high-pressure phase remained up to 28.5 GPa, suggesting no total amorphization in a helium pressure medium within the examined pressure region. These results suggest that the H-D isotope effect is engendered in the local environment surrounding H(D) atoms.
Nakazawa, Shinobu*; Teshima, Shotaro*; Arai, Daichi*; Miyagi, Daisuke*; Tsuda, Makoto*; Hamajima, Takataro*; Yagai, Tsuyoshi*; Nunoya, Yoshihiko; Koizumi, Norikiyo; Takahata, Kazuya*; et al.
Teion Kogaku, 46(8), p.474 - 480, 2011/08
It is observed that measured critical currents of a large current CIC conductor sample become lower than expected ones, since unbalanced current distribution is caused through contacting resistances between strands and Cu sleeves in CIC conductor joints. In order to evaluate the contacting length, we identify all strands 3 dimensional positions in the CIC conductor, and then we measure contacting number and lengths of strands which appear on surface of the cable for contacting with the Cu sleeves. It is found that some strands do not appear on the surface of cable and the contacting lengths are widely distributed with large standard deviation. We develop a numerical code which simulates strand positions in the CIC, and then compare the analyzed contacting strand number and contacting length with measured ones. It is found that the both results are in good agreement and hence the code is available for evaluating the contacting parameters. We vary twist pitches of sub-cables to search the contacting parameters and then show that all strands appear on the cable surface and have contacting lengths with small standard deviation. It is found that the twist pitches are a key parameter for optimization of the contacting parameters.
Yagi, Daichi*; Yamada, Taro*; Kurihara, Kazuo; Onishi, Yuki*; Yamashita, Masahiro*; Tamada, Taro; Tanaka, Ichiro*; Kuroki, Ryota; Niimura, Nobuo*
Acta Crystallographica Section D, 65(9), p.892 - 899, 2009/09
Times Cited Count:17 Percentile:79.90(Biochemical Research Methods)A neutron crystallographic analysis of phosphate-free bovine pancreatic RNase A has been carried out at 1.7 resolution using the BIX-4 single-crystal diffractometer at the JRR-3 reactor of the Japan Atomic Energy Agency. The high resolution structural model allowed us to determine that His12 acts mainly as a general base in the catalytic process of RNase A. Numerous other distinctive structural features such as the hydrogen positions of methyl groups, hydroxyl groups, prolines, asparagines and glutamines were also determined at 1.7
resolution. The protonation and deprotonation states of all of the charged amino-acid residues allowed us to provide a definitive description of the hydrogen-bonding network around the active site and the H atoms of the key His48 residue. Differences in hydrogen-bond strengths for the
-helices and
-sheets were inferred from determination of the hydrogen-bond lengths and the H/D-exchange ratios of the backbone amide H atoms. The correlation between the B factors and hydrogen-bond lengths of the hydration water molecules was also determined.
Yuguchi, Takashi*; Ito, Daichi*; Yokoyama, Tatsunori; Sakata, Shuhei*; Suzuki, Satoshi*; Ogita, Yasuhiro; Yagi, Koshi*; Imura, Takumi*; Motai, Satoko*; Ono, Takeshi*
no journal, ,
This study proposes a new method for elucidating zircon growth processes in the Okueyama granitic pluton, Kyushu, Japan. Our method, which combines 3D growth patterns, U-Pb ages, titanium concentration, and Th/U ratios, contributes to the petrology and mineralogy to understand the growth of zircon crystals within a magma chamber. Simultaneous determination of zircon U-Pb ages and titanium concentrations for the granite gives the variations in the temporal and thermal conditions during zircon growth, thus, developing a t-T history of the granitic magma before its solidification. The simultaneous determination of zircon U-Pb ages and Ti concentrations in the granite also enable us to associate the Th/U ratio with the crystallization temperature. Therefore, the decrease in zircon Th/U ratios as decreasing the temperature indicates the progression of fractional crystallization as the cooling of the magma chamber.
Ishibashi, Kozue*; Sakata, Shuhei*; Yokoyama, Tatsunori; Ito, Daichi*; Ogita, Yasuhiro; Yagi, Koshi*; Ono, Takeshi*; Yuguchi, Takashi*
no journal, ,
no abstracts in English
Ito, Daichi*; Ishibashi, Kozue*; Sakata, Shuhei*; Yokoyama, Tatsunori; Ogita, Yasuhiro; Yagi, Koshi*; Ono, Takeshi*; Yuguchi, Takashi*
no journal, ,
no abstracts in English
Yagi, Daichi*; Ebata, Toshinobu*; Ichige, Toshikatsu*; Kobayashi, Yoichiro*; Ishikawa, Takuya*; Yamashita, Masahiro*; Onishi, Yuki*; Tanaka, Ichiro*; Kurihara, Kazuo; Niimura, Nobuo*
no journal, ,
no abstracts in English