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King, G. E.*; Ahadi, F.*; Sueoka, Shigeru; Herman, F.*; Anderson, L.*; Gautheron, C.*; Tsukamoto, Sumiko*; Stalder, N.*; Biswas, R.*; Fox, M.*; et al.
Geology, 51(2), p.131 - 135, 2023/02
Sueoka, Shigeru; Iwano, Hideki*; Danhara, Toru*; Okamoto, Akira*; Tagami, Takahiro*
Fisshion, Torakku Nyusureta, (35), p.1 - 4, 2022/12
no abstracts in English
Nakajima, Toru; Fukuda, Shoma; Nagata, Mitsuhiro; Danhara, Toru*; Iwano, Hideki*; Sueoka, Shigeru
Fisshion, Torakku Nyusureta, (35), p.34 - 36, 2022/12
In this presentation, we report the results of fission-track etching experiments for the practical use of baddeleyite fission-track dating and a brief discussion of the results.
Fukuda, Shoma; Kohn, B. P.*; Sueoka, Shigeru; Danhara, Toru*; Iwano, Hideki*; Tagami, Takahiro*
Fisshion, Torakku Nyusureta, (35), p.7 - 10, 2022/12
In order to establish the age standard of zircon (U-Th)/He method, we performed zircon (U-Th)/He (hereinafter, ZHe) dating on 4 zircon samples. In this presentation, the Nohi rhyolite and the Mt. Wasso moonstone rhyolite as domestic samples, and Mt. Dromedary and OD-3 were also adopted as age standard zircons of fission-track and U-Pb methods. Consequently, regarding the ZHe age of the Nohi rhyolite indicated younger, which possibly reflected secondary heating, while ones of the others indicated consistent with previous thermochronometric data. Integrated with previously obtained ZHe data about 7 samples, the Utaosa rhyolite in the previous study showed a small age dispersion in grain ages, which infers a suitable candidate for the ZHe age standard. As future prospects, we are planning to conduct geochemical analyses and structure observations of these zircons for exploring the causal factors in age dispersions.
Minami, Saki*; Sueoka, Shigeru; Fukuda, Shoma; Nagata, Mitsuhiro; Kohn, B. P.*; Yokoyama, Tatsunori; Kagami, Saya; Kajita, Yuya*; Tagami, Takahiro*
Fisshion, Torakku Nyusureta, (35), p.22 - 26, 2022/12
no abstracts in English
Kajita, Yuya*; Sueoka, Shigeru; Fukuda, Shoma; Tagami, Takahiro*
Fisshion, Torakku Nyusureta, (35), p.19 - 21, 2022/12
no abstracts in English
Sasao, Eiji; Ishimaru, Tsuneari; Niwa, Masakazu; Shimada, Akiomi; Shimada, Koji; Watanabe, Takahiro; Sueoka, Shigeru; Yokoyama, Tatsunori; Fujita, Natsuko; Ogita, Yasuhiro; et al.
JAEA-Review 2022-022, 29 Pages, 2022/09
JAEA-Review-2022-022.pdf:0.97MB
This report is a plan of research and development (R&D) on geosphere stability for long-term isolation of high-level radioactive waste (HLW) in Japan Atomic Energy Agency (JAEA), in fiscal year 2022. The objectives and contents in fiscal year 2022 are described in detail based on the JAEA 4th Medium- and Long-term Plan (fiscal years 2022-2028). In addition, the background of this research is described from the necessity and the significance for site investigation and safety assessment, and the past progress. 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
Nagata, Mitsuhiro; Fukuda, Shoma; Sueoka, Shigeru; Nakajima, Toru; Kajita, Yuya*; Minami, Saki*; Okamoto, Akira*; Tagami, Takahiro*
Fisshion, Torakku Nyusureta, (35), p.15 - 18, 2022/09
We performed U-Pb dating on zircons from the Utaosa Rhyolite of the Teragi Group as part of the search for standard materials for dating of zircons. Previous studies about Utaosa Rhyolite have reported ca. 2.30-2.77 Ma zircon fission track, zircon (U-Th)/He, and biotite K-Ar ages. U-Pb dating was carried out on the multi-collector inductively coupled plasma mass spectrometer with a laser ablation system. The weighted mean 
U-
Pb ages of 2.65
0.16 Ma and 2.660.15 Ma were obtained from two samples. These ages are consistent with the ages from the previous studies. Therefore the results show that zircons from the Utaosa Rhyolite may be effective as a standard material.
Suzuki, Kota*; Kawakami, Tetsuo*; Sueoka, Shigeru; Yamazaki, Ayu*; Kagami, Saya; Yokoyama, Tatsunori; Tagami, Takahiro*
Island Arc, 31(1), p.e12462_1 - e12462_15, 2022/09
Times Cited Count：0 Percentile：0(Geosciences, Multidisciplinary)Ogata, Manabu; King, G. E.*; Herman, F.*; Sueoka, Shigeru
Earth and Planetary Science Letters, 591, p.117607_1 - 117607_14, 2022/08
Times Cited Count：0 Percentile：0.01(Geochemistry & Geophysics)Optically stimulated luminescence (OSL)-thermometry can be used to reconstruct the thermal structure in slowly denuded regions where infrared stimulated luminescence (IRSL) signals of samples obtained from deep boreholes are measured and evaluated with depth. Until now, only one study has explored this approach, using a target mineral of Na-feldspar. In this study, we applied multi-OSL-thermometry to K-feldspar obtained from deep borehole core samples (MIZ-1) drilled at the Tono region, central Japan, which is a well-documented thermally stable crustal environment. The inverted temperature for the IRSL 50 
C of the samples at a depth of 
1 km (40 C) were consistent with the in-situ temperature. The results suggest that the application of OSL-thermometry to K-feldspar in a borehole is useful to reconstruct the paleothermal condition.
Sueoka, Shigeru; Kobayashi, Yumi*; Fukuda, Shoma; Kohn, B. P.*; Yokoyama, Tatsunori; Sano, Naomi*; Hasebe, Noriko*; Tamura, Akihiro*; Morishita, Tomoaki*; Tagami, Takahiro*
Tectonophysics, 828, p.229231_1 - 229231_17, 2022/04
Times Cited Count：1 Percentile：0.01(Geochemistry & Geophysics)The South Fossa Magna zone, central Japan, has been an active collision zone between the Honshu Arc and the Izu-Bonin Arc since the middle Miocene and provides an excellent setting for reconstructing the earliest stages of continent formation. Multi-system geo-thermochronometry was applied to different domains of the South Fossa Magna zone, together with some previously published data, to reveal mountain formation processes, i.e., vertical crustal movements. Nine granitic samples yielded zircon U-Pb ages of 10.2-5.8 Ma (
= 2), apatite (U-Th)/He (AHe) ages of 42.8-2.6 Ma ( = 7), and apatite fission-track (AFT) ages of 44.1-3.0 Ma ( = 9). Thermal history inversion modeling based on the AHe and AFT data suggested rapid cooling events confined within the study region at 6-2 Ma. The Kanto Mountains may have undergone a domal uplift in association with their collision with the Tanzawa Block at 5 Ma. However, this uplift may have slowed down following the migration of the plate boundary and late Pliocene termination of the Tanzawa collision. The Minobu Mountains and possibly adjacent mountains may have been uplifted by the motional change of the Philippine Sea plate at 3 Ma. Therefore, the mountain formation in the South Fossa Magna zone was mainly controlled by collisions of the Tanzawa and Izu Blocks and motional change of the Philippine Sea plate. Earlier collisions of the Kushigatayama Block at 13 Ma and Misaka Block at 10 Ma appeared to have had little effect on mountain formation. Together with a 90 deg. clockwise rotation of the Kanto Mountains at 12-6 Ma, these observations suggest that horizontal deformation predominated during the earlier stage of arc-arc collision, and vertical movements due to buoyancy resulting from crustal shortening and thickening developed at a later stage.
Balkanska, E.*; Georgiev, S.*; Kounov, A.*; Anti
, M.*; Tagami, Takahiro*; Sueoka, Shigeru; Wijbrans, J.*; Peytcheva, I.*
Geologica Carpathica, 73(1), p.3 - 23, 2022/02
Times Cited Count：0 Percentile：0(Geosciences, Multidisciplinary)Minami, Saki*; Nagata, Mitsuhiro; Sueoka, Shigeru; Fukuda, Shoma; Kajita, Yuya*; Ogita, Yasuhiro; Kagami, Saya; Yokoyama, Tatsunori; Tagami, Takahiro*
Earth, Planets and Space (Internet), 73(1), p.231_1 - 231_7, 2021/12
Times Cited Count：1 Percentile：18.41(Geosciences, Multidisciplinary)Fukuda, Shoma; Sueoka, Shigeru; Kanno, Mizuho; Kohn, B. P.*; Tagami, Takahiro*
Fisshion, Torakku Nyusureta, (34), p.9 - 13, 2021/12
In order to explore suitable zircon samples as standard minerals for the zircon (U-Th)/He (namely, ZHe) method, we have attempted to conduct ZHe analyses of the Nisatai dacite sampled in Iwate prefecture. Previous researches reported solid ages at 22-21 Ma and a rapid cooling pattern based on various geochronometric investigations, which inferred a potential of an age standard for ZHe method. Consequently, ZHe ages in this study yielded at 21.5 0.2 Ma having wide dispersion of grain ages from 40 Ma to 15 Ma, probably caused by random errors. As possible causes of age dispersion, the zoning of parent nuclei in a crystal and the heterogeneous rock pieces revealed by observations of thin-section are considerable. Therefore, the Nisatai dacite was concluded as unsuitable sample for the ZHe age standard. However, geochronologic data of other methods showed comparable ages such as zircon fission-track and U-Pb method, the Nisatai dacite may be used as these age standards. We will continue to explore another candidates for ZHe age standard, e.g., U-Pb age standards.
Kajita, Yuya*; Sueoka, Shigeru; Fukuda, Shoma; Yokoyama, Tatsunori; Kagami, Saya; Nagata, Mitsuhiro; Tagami, Takahiro*
Fisshion, Torakku Nyusureta, (34), p.14 - 16, 2021/12
For reconstructing the uplift/denudation history of the fore-arc side of the NE Japan Arc on geologic timescales, U-Pb dating and apatite fission-track (AFT) thermochronometry were applied to granitoids in Kitakami mountains. In addition, U-Pb dating for the Jodogahama rhyolite at the easternmost Kitakami mountains was also carried out to estimate the timing of volcanism and its thermal effect. Consequently, U-Pb ages of 122.7 Ma and 117.3 Ma for 2 samples of the Cretaceous granites and AFT ages ranging from 156.8 Ma to 70.3 Ma of 15 samples were obtained. Concerning the Jodogahama rhyolite, U-Pb age of 44.3 Ma was obtained. Integrated AFT data of this study and previous ones in Kitakami mountains, the trend of ages shows younging toward west. Although such age trend can be explained by volcanism of the Jodogahama reflecting the migration of a paleo-volcanic front, all AFT ages exhibited significantly older than U-Pb data of the Jodogahama and the thermal inverse modeling based on track length distributions provided slow cooling patterns. These observations did not supported the reheating of volcanism as a cause of age trend. As future prospects, we are planning to improve the reliability of age data based on additional analyses and apply an ultra low-temperature thermochronometer, e.g., ESR method.
Minami, Saki*; Nagata, Mitsuhiro; Sueoka, Shigeru; Fukuda, Shoma; Kajita, Yuya*; Ogita, Yasuhiro; Yokoyama, Tatsunori; Kagami, Saya; Tagami, Takahiro*
Fisshion, Torakku Nyusureta, (34), p.4 - 8, 2021/12
This study employed U-Pb dating for determining the intrusive age of young (several Ma) granitoids in Tanigawa-dake area, where rapid and intense uplift/denudation has probably occurred in Japan. As results, U-Pb age of 109 Ma for the Cretaceous granodiorite and 3.95-3.19 Ma about 3 samples of the Pliocene granodiorites were obtained. These U-Pb ages showed consistent with previously reported ages based on thermochronometers having lower closure temperatures such as K-Ar or zircon fission-track methods. All previous data indicated younger ages than U-Pb ones in this study. Therefore, our U-Pb data can be interpreted as intrusive ages of young granitoids, inferring multiple events possibly occurred at least twice and contributed to the formation in young granitoids in the Tanigawa-dake area.
Nakajima, Toru; Fukuda, Shoma; Ogata, Manabu; Sueoka, Shigeru
Fisshion, Torakku Nyusureta, (34), p.25 - 26, 2021/12
The 17th International Conference on Thermochronology (Thermo2021) was held on September 12-17, 2021 at the Eldorado Resort in downtown Santa Fe, New Mexico, USA. Due to the social situation and the spread of the COVID-19, the event had been postponed. In this paper, I report on the circumstances surrounding our participation in the conference, the contents and trends of the presentations made at the conference, and the tasks for the 2023 and 2025 conferences.
Ishimaru, Tsuneari; Ogata, Nobuhisa; Kokubu, Yoko; Shimada, Koji; Niwa, Masakazu; Shimada, Akiomi; Watanabe, Takahiro; Sueoka, Shigeru; Yokoyama, Tatsunori; Fujita, Natsuko; et al.
JAEA-Research 2021-007, 65 Pages, 2021/10
JAEA-Research-2021-007.pdf:4.21MB
This annual report documents the progress of research and development (R&D) in the 6th fiscal year during the JAEA 3rd Mid- and Long-term Plan (fiscal years 2015-2021) to provide the scientific base for assessing geosphere stability for long-term isolation of the high-level radioactive waste. The planned 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. The current status of R&D activities with previous scientific and technological progress is summarized.
Ishimaru, Tsuneari; Kokubu, Yoko; Shimada, Koji; Shimada, Akiomi; Niwa, Masakazu; Watanabe, Takahiro; Sueoka, Shigeru; Yokoyama, Tatsunori; Fujita, Natsuko; Ogita, Yasuhiro; et al.
JAEA-Review 2021-012, 48 Pages, 2021/08
JAEA-Review-2021-012.pdf:1.64MB
This report is a plan of research and development (R&D) on geosphere stability for long-term isolation of high-level radioactive waste (HLW) in Japan Atomic Energy Agency (JAEA), in fiscal year 2021. The objectives and contents in fiscal year 2021 are described in detail based on the JAEA 3rd Medium- and Long-term Plan (fiscal years 2015-2021). In addition, the background of this research is described from the necessity and the significance for site investigation and safety assessment, and the past progress. 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.
Tateishi, Ryo*; Shimada, Koji; Shimizu, Mayuko; Ueki, Tadamasa*; Niwa, Masakazu; Sueoka, Shigeru; Ishimaru, Tsuneari
Oyo Chishitsu, 62(2), p.104 - 112, 2021/06
We attempted to discriminate between active and non-active faults by linear discriminant analysis using the chemical composition data of fault gouges in Japan, and then examined the elements that represent the difference between them and better discriminants. As a result, the multiple discriminants obtained could discriminate between them with high probability. In addition, the generalization performance of these discriminants is discussed, and the discriminants that can be expected to have high discriminant performance for unknown samples are presented. Also, from the combination of elements common to these discriminants, we narrowed down the number of elements that represent the difference between active and non-active faults to 6, and showed that the combination of TiO
and Sr contributing the most to the discrimination. The method applied in this study is an innovative one that can discriminate the activity by chemical analysis of fault rocks that are universally present in the bedrock.
