Potential of the young age reference materials; CA-ID-TIMS U-Pb dates of Cenozoic zircons in Japan

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.

Spatial distributions of low-temperature thermochronometric data in Shikoku mountains and these interpretations

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.

The Impact of climate on relief in the northern Japanese Alps within the past 1 Myr; The case of the Tateyama mountains

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

https://doi.org/10.1016/j.epsl.2024.118830

Short communication: Inverse correlation between radiation damage and fission-track etching time on monazite

Nakajima, Toru; Fukuda, Shoma; Sueoka, Shigeru; Niki, Sota*; Kawakami, Tetsuo*; Danhara, Toru*; Tagami, Takahiro*

Geochronology (Internet), 6(3), p.313 - 323, 2024/07

https://doi.org/10.5194/gchron-6-313-2024

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 90C 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.

Thermochronology of hydrothermal alteration zones in the Kii Peninsula, southwest Japan; An Attempt for detecting the thermal anomalies and implications to the regional exhumation history

Sueoka, Shigeru; Iwano, Hideki*; Danhara, Toru*; Niwa, Masakazu; Kanno, Mizuho; Kohn, B. P.*; Kawamura, Makoto; Yokoyama, Tatsunori; Kagami, Saya; Ogita, Yasuhiro; et al.

Earth, Planets and Space (Internet), 75(1), p.177_1 - 177_24, 2023/12

https://doi.org/10.1186/s40623-023-01921-5

Fluid-inclusion and thermochronometric analyses have been applied to hydrothermal alteration zones and their host rocks outcropping in the Hongu area of the Kii Peninsula, southwestern Japan in an attempt to detect thermal anomalies related to hydrothermal events and quantify the thermal effects on the host rocks. Hydrothermal events at ca 150 deg. C and ca 200 deg. C were identified by fluid-inclusion microthermometry of quartz veins in the alteration zones. For the host rocks and alteration zones, in the youngest population zircon yielded U-Pb dates ranging between ca 74.7-59.2 Ma, fission-track dates of ca 27.2-16.6 Ma, and (U-Th)/He single-grain dates of ca 23.6-8.7 Ma. Apatite yielded pooled fission-track ages of ca 14.9-9.0 Ma. The zircon U-Pb dates constrain the maximum depositional ages of the sedimentary samples. However, the fission-track and (U-Th)/He dates show no clear trend as a function of distance from the alteration zones. Hence, no thermal anomaly was detected in the surrounding host rocks based on the thermochronometric data patterns. The fission-track and (U-Th)/He dates are rather thought to record regional thermal and exhumation histories rather than a direct thermal imprint of fluid flow, probably because the duration of such activity was too short or because fluid flow occurred before regional cooling events and were later thermally overprinted. Apatite fission-track ages of ca 10 Ma may reflect regional mountain uplift and exhumation related to the obduction of the SW Japan lithospheric sliver onto the Shikoku Basin, or the rapid subduction of the Philippine Sea slab associated with the clockwise rotation of the Southwest Japan Arc.

Exhumation history of the Kurobe area, Hida Range, based on solidification ages and depths of the Pliocene-Quaternary plutons

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

https://ftrgj.org/FTNLs/FTNL36/FTNL36ALL.pdf

no abstracts in English

Zircon U-Pb dates from the Taiheizan Complex Plutons in Akita Prefecture, NE Japan

Nakajima, Toru; Nagata, Mitsuhiro; Fukuda, Shoma; Sueoka, Shigeru

Chishitsugaku Zasshi (Internet), 129(1), p.503 - 507, 2023/11

https://doi.org/10.5575/geosoc.2023.0016

Zircon U-Pb dating was carried out on granitic rocks from plutons in the Taiheizan Complex in Akita Prefecture, NE Japan. Two granodiorites from the Main Intrusive Rocks yielded weighted mean 206Pb/238U dates of 103.41.0 Ma and 115.61.1 Ma (1SE). Three porphyrygranite from the Young Intrusive Rocks yielded weighted mean 206Pb/238U dates of 11.40.1 Ma, 4.70.1Ma, and 4.80.1 Ma (1SE). The older and younger dates can be interpreted as the ages of early and later stages of granitic intrusion at the sampling locations. The Pliocene U-Pb dates suggest that the Nibetsu Body in the Young Intrusive Rocks is one of the youngest granitic plutons currently exposed on Earth.

Annual report for research on geosphere stability for long-term isolation of radioactive waste in fiscal year 2022

Niwa, Masakazu; Shimada, Koji; Sueoka, Shigeru; Ishihara, Takanori; Ogawa, Hiroki; Hakoiwa, Hiroaki; Watanabe, Tsuyoshi; Nishiyama, Nariaki; Yokoyama, Tatsunori; Ogata, Manabu; et al.

JAEA-Research 2023-005, 78 Pages, 2023/10

JAEA-Research-2023-005.pdf:6.51MB

This annual report documents the progress of research and development (R&D) in the 1st fiscal year of the Japan Atomic Energy Agency 4th Medium- and Long-term Plan (fiscal years 2022-2028) to provide the scientific base for assessing geosphere stability for long-term isolation of high-level radioactive waste. 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. The current status of R&D activities with previous scientific and technological progress is summarized.

Thermochronological data in the Kitakami Mountains and their interpretation

Kajita, Yuya*; Sueoka, Shigeru; Fukuda, Shoma; Tagami, Takahiro*

Fuisshon, Torakku Nyusureta, (35), p.19 - 21, 2022/12

no abstracts in English

Evaluation of potential age standards for zircon (U-Th)/He thermochronometry; Results from further chronometric investigations

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.