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Nagata, Mitsuhiro; Fukuda, Shoma; Sueoka, Shigeru; Nakajima, Toru; Yokoyama, Tatsunori; Wall, C. J.*; Danhara, Toru*; Iwano, Hideki*; Tagami, Takahiro*
Fuisshon, Torakku Nyusureta, (37), p.11 - 13, 2024/12
In recent years, advances in analytical technology have made it possible to measure the U-Th-Pb dating of young geological units (e.g. 
1 Ma). However, there are very few young standard samples available for evaluation. In this study, we attempted U-Pb dating using isotope dilution Thermal Ionization Mass Spectrometry (ID-TIMS) on young zircon samples (TRG04 and OGPK). As a result, we obtained preliminary U-Pb ages of 2.6654 
0.0016 Ma and 1.1266 0.0014 Ma, respectively.
Fukuda, Shoma; Okamoto, Akira*; Kohn, B.*; Shinjo, Hironao*; Sueoka, Shigeru; Tagami, Takahiro*
Fuisshon, Torakku Nyusureta, (37), p.8 - 10, 2024/12
The Shikoku Mountains are a non-volcanic uplift zone parallel to the subduction zone of the Philippine Sea Plate, and elucidation of its mountain building process is expected to contribute to constraining the long-term strain accumulation and release mechanism in the Nankai Trough. In this study, we attempted thermochronological analysis of nine granitoids of the Permian to Miocene age in the Shikoku Mountains using apatite and zircon (U-Th)/He (AHe, ZHe) and apatite fission-track (AFT) methods, which can provide thermal and exhumation history in the shallower crust (2 to 6 km depth). AHe and ZHe dating was conducted at the University of Melbourne, and AFT dating at the Tono Geoscience Center. AHe ages for eight samples ranged from about 55 to 7 Ma, AFT ages for five samples ranged from about 90 to 70 Ma, and ZHe ages for nine samples ranged from about 200 to 70 Ma. These data showed a consistent relationship considering the closure temperature of each method. They are also generally consistent with previously reported ZFT ages, biotite K-Ar ages, and AHe, AFT, and ZHe ages.
Bartz, M.*; King, G. E.*; Bernard, M.*; Herman, F.*; Wen, X.*; Sueoka, Shigeru; Tsukamoto, Sumiko*; Braun, J.*; Tagami, Takahiro*
Earth and Planetary Science Letters, 644, p.118830_1 - 118830_11, 2024/10
Times Cited Count：1 Percentile：0.00(Geochemistry & Geophysics)Nakajima, Toru; Fukuda, Shoma; Sueoka, Shigeru; Niki, Sota*; Kawakami, Tetsuo*; Danhara, Toru*; Tagami, Takahiro*
Geochronology (Internet), 6(3), p.313 - 323, 2024/07
In this study, we explored the impacts of radiation damage and chemical composition on the etching time of fission tracks in monazite. Despite the potential of monazite fission-track (MFT) dating as an ultralow-temperature thermochronology, the comprehensive effects of radiation damage and non-formula elements, especially on the etching rate of MFTs, remain unexplored, and established analytical procedures are lacking. We quantified the degree of radiation damage (dFHWM) in Cretaceous to Quaternary monazites distributed in the Japan arc through Raman spectroscopy and chemical composition analyses. Subsequently, MFT etching was performed to examine the correlation between these parameters and the etching time. Estimation of the degree of radiation damage showed an increase in radiation damage corresponding to the cooling age of each geological unit. For example, the Toya ignimbrite (ca. 0.1 Ma) and the Kurobegawa granodiorite (0.8 Ma), both of which are types of monazite from Quaternary geological units, have dFHWM values of 0.27 and 0.55 cm
, respectively. In contrast, the Muro ignimbrite (ca. 15 Ma) has a dFHWM value of 4.01 cm, while the Kibe granite and the Sagawa granite, both of which are Cretaceous granitoids, yielded 7.35 and 6.31 cm, respectively. MFT etching of these samples according to the existing recipe (6M HCl at 90
C for 60-90 min) was completed at 1200, 860, 210, 120, and 90 min for the Toya ignimbrite, Kurobegawa granodiorite, Muro ignimbrite, Sagawa granite, and Kibe granite, respectively.
Nakajima, Toru; Sueoka, Shigeru; Nagata, Mitsuhiro; Kohn, B. P.*; Ramos, N. T.*; Tsutsumi, Hiroyuki*; Tagami, Takahiro*
Earth, Planets and Space (Internet), 75(1), p.176_1 - 176_11, 2023/12
Times Cited Count：1 Percentile：24.68(Geosciences, Multidisciplinary)Geo- and thermochronological methods were applied to dioritic rocks from the Cordillera Central, Luzon, Philippines, to understand their emplacement and exhumation history in the island arc mountains. Zircon U-Pb ages range from 32.54 0.70 to 6.11 0.15 (2SE) Ma, indicating that dioritic magmas intruded the middle and upper crust intermittently during Tertiary magmatism. Zircon fission-track (ZFT) pooled ages range from 35.63 2.17 to 6.91 0.36 (2SE) Ma, and are generally comparable with the U-Pb ages at each locality. These results suggest that the diorites cooled rapidly below 250-350 degree, (i.e. through the partial annealing zone of the ZFT system), following their intrusion. On the other hand, the zircon and apatite (U-Th-Sm)/He (ZHe and AHe) weighted mean ages, ranging from 11.71 0.36 to 8.82 0.26 and 9.21 0.52 to 0.98 0.088 (2SE) Ma respectively, indicate a decrease in cooling rates at a lower temperature range, especially through the partial retention zone of the AHe system. This observation suggests that the ZFT ages reflect initial cooling of the dioritic magma, whereas the AHe ages reflect the cooling history associated with regional exhumation following the initial cooling phase. Spatial distribution of the AHe ages suggest that rapid exhumation of the Cordillera Central during the Quaternary resulted from the block-like uplift of the entire mountain range.
Kajita, Yuya*; Sueoka, Shigeru; Tani, Atsushi*; Isotani, Shusuke*; Tagami, Takahiro*
Fuisshon, Torakku Nyusureta, (36), p.6 - 8, 2023/12
no abstracts in English
Sueoka, Shigeru; Kawakami, Tetsuo*; Suzuki, Kota*; Kagami, Saya; Yokoyama, Tatsunori; Shibazaki, Bunichiro*; Nagata, Mitsuhiro; Yamazaki, Ayu*; Higashino, Fumiko*; King, G. E.*; et al.
Fuisshon, Torakku Nyusureta, (36), p.1 - 3, 2023/12
no abstracts in English
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
Fukuda, Shoma; Kohn, B. P.*; Sueoka, Shigeru; Danhara, Toru*; Iwano, Hideki*; Tagami, Takahiro*
Fuisshon, 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*
Fuisshon, Torakku Nyusureta, (35), p.22 - 26, 2022/12
no abstracts in English
Sueoka, Shigeru; Iwano, Hideki*; Danhara, Toru*; Okamoto, Akira*; Tagami, Takahiro*
Fuisshon, Torakku Nyusureta, (35), p.1 - 4, 2022/12
no abstracts in English
Kajita, Yuya*; Sueoka, Shigeru; Fukuda, Shoma; Tagami, Takahiro*
Fuisshon, Torakku Nyusureta, (35), p.19 - 21, 2022/12
no abstracts in English
Nagata, Mitsuhiro; Fukuda, Shoma; Sueoka, Shigeru; Nakajima, Toru; Kajita, Yuya*; Minami, Saki*; Okamoto, Akira*; Tagami, Takahiro*
Fuisshon, 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 2.650.16 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：2 Percentile：15.26(Geosciences, Multidisciplinary)Kinoshita, Takahiro*; Okamura, Shigeki*; Nishino, Hiroyuki; Yamano, Hidemasa; Kurisaka, Kenichi; Futagami, Satoshi; Fukasawa, Tsuyoshi*
Transactions of the 26th International Conference on Structural Mechanics in Reactor Technology (SMiRT-26) (Internet), 7 Pages, 2022/07
The seismic evaluation of key components such as reactor vessel is important for the Seismic Probabilistic Risk Assessment (S-PRA) in a Sodium-Cooled Fast Reactor (SFR). Many components were damaged by cumulative damage like fatigue damage during seismic ground motion. However, general evaluation method for key components under seismic ground motion has been based on static loads and elastic region of materials. More accurate evaluation method for S-PRA, which can evaluate the failure of key components such as reactor vessels, has been actually required. In this study, failure probability evaluation method with integrated energy was developed by comparing the energy with vibration tests and fatigue tests. Vibration tests were performed to evaluate integrated vibration energy at failure by energy balance equation and fatigue tests were performed to evaluate integrated vibration energy at failure based on experimental results of fatigue tests.
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：9.95(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：4 Percentile：48.39(Geology)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：4.99(Geosciences, Multidisciplinary)Minami, Saki*; Nagata, Mitsuhiro; Sueoka, Shigeru; Fukuda, Shoma; Kajita, Yuya*; Ogita, Yasuhiro; Yokoyama, Tatsunori; Kagami, Saya; Tagami, Takahiro*
Fuisshon, 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.
Fukuda, Shoma; Sueoka, Shigeru; Kanno, Mizuho; Kohn, B. P.*; Tagami, Takahiro*
Fuisshon, 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.
