Outlining zircon growth in a granitic pluton using 3D cathodoluminescence patterns, U-Pb age, titanium concentration, and Th/U; Implications for the magma chamber process of Okueyama granite, Kyushu, Japan

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

https://doi.org/10.1016/j.lithos.2023.107026

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.

Simultaneous determination of zircon crystallisation age and temperature; Common thermal evolution of mafic magmatic enclaves and host granites in the Kurobegawa granite, central Japan

Yuguchi, Takashi*; Yamazaki, Hayato*; Ishibashi, Kozue*; Sakata, Shuhei*; Yokoyama, Tatsunori; Suzuki, Satoshi*; Ogita, Yasuhiro; Sando, Kazusa*; Imura, Takumi*; Ono, Takeshi*

Journal of Asian Earth Sciences, 226, p.105075_1 - 105075_9, 2022/04

https://doi.org/10.1016/j.jseaes.2021.105075

Simultaneous determination of the U-Pb age of zircon and concentration of titanium in a single analysis spot, using inductively coupled plasma mass spectrometry with laser ablation sample introduction, produces paired age and temperature data of zircon crystallisation, potentially revealing time-temperature () histories for evolved magma. The Kurobegawa granite, central Japan, contains abundant mafic magmatic enclaves (MMEs). We applied this method to evaluate MMEs and their host (enclosing) granites. Cooling behaviour common to both MMEs and host rocks was found between 1.5 and 0.5 Ma. Rapid cooling from the zircon crystallisation temperature to the closure temperature of biotite K-Ar system was within 1 million year. Combining the obtained paths of MMEs and host rocks with petrological information can provide insights into magma chamber processes. This suggests that MME flotation, migration, and spread through the magma chamber ceased at 1.5-0.5 Ma, indicating the emplacement age of the Kurobegawa granitic pluton, as no large-scale reheating episodes have occurred since then.

Radioactivity and radionuclides in deciduous teeth formed before the Fukushima-Daiichi Nuclear Power Plant accident

Takahashi, Atsushi*; Chiba, Mirei*; Tanahara, Akira*; Aida, Jun*; Shimizu, Yoshinaka*; Suzuki, Toshihiko*; Murakami, Shinobu*; Koarai, Kazuma; Ono, Takumi*; Oka, Toshitaka; et al.

Scientific Reports (Internet), 11(1), p.10355_1 - 10355_11, 2021/05

https://doi.org/10.1038/s41598-021-89910-0

Morphological reproductive characteristics of testes and fertilization capacity of cryopreserved sperm after the Fukushima accident in raccoon ()

Komatsu, Kazuki*; Iwasaki, Tsugumi*; Murata, Kosuke*; Yamashiro, Hideaki*; Goh, V. S. T.*; Nakayama, Ryo*; Fujishima, Yohei*; Ono, Takumi*; Kino, Yasushi*; Shimizu, Yoshinaka*; et al.

Reproduction in Domestic Animals, 56(3), p.484 - 497, 2021/03

https://doi.org/10.1111/rda.13887

We have established an archive system of livestock and wild animals from the surrounding ex-evacuation zone. Wildlife within the alert zone have been exposed to low-dose-rate (LDR) radiation for a long and continuous time. In this study, we analysed the morphological characteristics of the testes and in vitro fertilization (IVF) capacity of cryopreserved sperm of raccoons from the ex-evacuation zone of the FDNPP accident. This study revealed that the chronic and LDR radiation exposure associated with the FDNPP accident had no adverse effect on the reproductive characteristics and functions of male raccoons.

Application of automated particle screening for effective analysis of individual uranium particles by thermal ionization mass spectrometry

Esaka, Fumitaka; Suzuki, Daisuke; Yomogida, Takumi; Magara, Masaaki

Analytical Methods, 8(7), p.1543 - 1548, 2016/02

AA2015-0572.pdf:0.66MB

https://doi.org/10.1039/C5AY02841H

The isotope ratio analysis of individual uranium particles in environmental samples taken at nuclear facilities is important to clarify their origins for nuclear safeguards. In the present study, automated particle screening was used to select uranium particles prior to precise isotope ratio analysis by thermal ionization mass spectrometry (TIMS). As a result, molecular ion interferences on the uranium mass region were able to be almost completely avoided in the analysis of real inspection samples using APM-TIMS. Therefore, the performance of APM-TIMS was sufficient for obtaining isotope ratio data of individual particles without molecular ion interferences.

Growth of single-phase nanostructured ErO thin films on Si (100) by ion beam sputter deposition

Mao, W.*; Fujita, Masaya*; Chikada, Takumi*; Yamaguchi, Kenji; Suzuki, Akihiro*; Terai, Takayuki*; Matsuzaki, Hiroyuki*

Surface & Coatings Technology, 283, p.241 - 246, 2015/12

https://doi.org/10.1016/j.surfcoat.2015.10.060

Single-phase nanocrystalline thin films of ErO (440) has been first prepared using Si (100) substrates by ion beam sputter deposition at 973 K at a pressure of 10 Pa and - annealing at 1023 K at a pressure of 10 Pa. Er silicides formed during the deposition are eliminated via the annealing, which results in the single phase and the smooth surface of the ErO thin films. The epitaxial relationship between Si (100) and ErO (110) is clarified by X-ray diffraction and reflection high energy electron diffraction.

SiC coating as hydrogen permeation reduction and oxidation resistance for nuclear fuel cladding

Usui, Takahiro*; Sawada, Akihiko; Amaya, Masaki; Suzuki, Akihiro*; Chikada, Takumi*; Terai, Takayuki*

Journal of Nuclear Science and Technology, 52(10), p.1318 - 1322, 2015/10

https://doi.org/10.1080/00223131.2015.1020901

SiC coating is one of countermeasures for the prevention of oxidation and hydrogen embrittlement of fuel claddings because SiC has high resistance of oxidation and hydrogen permeation. Hydrogen permeation and oxidation experiments for the cladding materials with SiC coatings were conducted in unirradiated conditions. The sputtering method was employed to make SiC coatings. In the hydrogen permeation experiment, SUS316 was used as a base material of the coating. SUS316 with SiC coatings showed hydrogen permeation reduction by one order of magnitude. In the oxidation experiments, Zry-4 and SUS316 were used as base materials of the coatings. The weight gain of the Zry-4 specimens with a SiC coating decreased by about one-fifth compared to the uncoated ones. This phenomenon was observed for SUS316 at 750 C as well. The peel-off of the coating was observed in some experiments, and it is considered that the peel-off was caused by the difference of the thermal expansions between coatings and base materials. Thicker coatings showed better oxidation resistance, but thinner coatings showed more tolerance of peel-off.

Recent progress on tritium technology research and development for a fusion reactor in Japan Atomic Energy Agency

Hayashi, Takumi; Nakamura, Hirofumi; Kawamura, Yoshinori; Iwai, Yasunori; Isobe, Kanetsugu; Yamada, Masayuki; Suzuki, Takumi; Kurata, Rie; Oyaizu, Makoto; Edao, Yuki; et al.

Fusion Science and Technology, 67(2), p.365 - 370, 2015/03

https://doi.org/10.13182/FST14-T31

Sputtering of SiN films by 540 keV C ions observed using high-resolution Rutherford backscattering spectroscopy

Nakajima, Kaoru*; Morita, Yosuke*; Kitayama, Takumi*; Suzuki, Motofumi*; Narumi, Kazumasa; Saito, Yuichi; Tsujimoto, Masahiko*; Isoda, Shoji*; Fujii, Yoshikazu*; Kimura, Kenji*

Nuclear Instruments and Methods in Physics Research B, 332, p.117 - 121, 2014/08

https://doi.org/10.1016/j.nimb.2014.02.042

Size and elemental analyses of nano colloids in deep granitic groundwater; Implications for transport of trace elements

Saito, Takumi*; Suzuki, Yohei*; Mizuno, Takashi

Colloids and Surfaces A; Physicochemical and Engineering Aspects, 435(Sp.IAP2012), p.48 - 55, 2013/10

https://doi.org/10.1016/j.colsurfa.2012.11.031

Nano colloids in granitic groundwater obtained from a borehole located at the -300-m stage of the Mizunami Underground Research Laboratory were studied in terms of their size distributions by flow-field flow fractionation. In order to deal with relatively low concentrations of colloids, colloids were enriched first by ultrafiltration, and then by in-situ enrichment using a large injection loop and the slot flow technique. The size distributions of organic and inorganic constituents of colloids were measured by UV/Vis, fluorescence and inductively coupled plasma mass spectrometry, from which possible association of trace elements with host colloidal phases consisting of major elements and organic materials was discussed. Trace elements, namely, Sr, lanthanides (La, Ce, Eu, Lu), actinide elements (U, Th) and heavy metals (Cu, Zn and W), exhibited distinct size distributions, reflecting their preferential association with certain host colloidal phases.