Low-temperature thermochronology of active arc-arc collision zone, South Fossa Magna region, central Japan

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

https://doi.org/10.1016/j.tecto.2022.229231

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.

Quantitative micro-X-ray fluorescence scanning spectroscopy of wet sediment based on the X-ray absorption and emission theories; Its application to freshwater lake sedimentary sequences

Katsuta, Nagayoshi*; Takano, Masao*; Sano, Naomi; Tani, Yukinori*; Ochiai, Shinya*; Naito, Sayuri*; Murakami, Takuma*; Niwa, Masakazu; Kawakami, Shinichi*

Sedimentology, 66(6), p.2490 - 2510, 2019/10

https://doi.org/10.1111/sed.12603

Micro-X-ray fluorescence (XRF) scanning spectroscopy of marine and lake sedimentary sequences can provide detailed paleoenvironmental records available through element intensities proxy data. However, problems for effects of interstitial pore water on the micro-XRF intensities have been pointed out so far because of direct measurement on the split wet sediment surfaces. In this study, new methods for the XRF corrections were developed by being considered with the micro-X-ray scanning spectroscopy.

Quick examination of heavy mineral composition based on chemical analysis using electron probe microanalyzer in the Tono Geoscience Center

Yonaga, Yusuke; Shimizu, Mayuko; Sano, Naomi; Ueki, Tadamasa; Yoshikawa, Kiyotaka*; Niwa, Masakazu

JAEA-Testing 2018-001, 29 Pages, 2018/07

JAEA-Testing-2018-001.pdf:3.82MB
JAEA-Testing-2018-001-appendix(CD-ROM).zip:1.64MB

Study on the formation process of mountains provides important clues for evaluating the uplift and erosion related to long-term changes of geological environment for geological disposal. Provenance analysis of detrital sediments is often be effective to understand the process. In the Tono Geoscience Center, quick and efficient mineralogical and chemical analyses for heavy minerals in basement rocks and sediments have been developed using the electron probe microanalyzer (JEOL JXA-8530F EPMA), as one of the promising tool for provenance analysis. To contribute evaluation of the analyses, sample preparation and EPMA analyses of heavy minerals were shown in this paper.

Quantitative X-ray Fluorescence analysis of major and trace elements in rock samples at Tono Geoscience Center

Shimizu, Mayuko; Sano, Naomi; Shibata, Kenji*

JAEA-Testing 2016-004, 40 Pages, 2017/02

JAEA-Testing-2016-004.pdf:2.69MB

X-ray fluorescence analysis is one of the methods commonly used to reveal whole-rock chemical composition, which is basic information of rock samples. This report shows methods to prepare glass beads of fused samples and to use the X-ray fluorescence spectrometer (Rigaku ZSX Primus II) housed in Tono Geoscience Center, and the evaluation of precision and accuracy of the measurement.

Annual report on the environmental radiation monitoring around Toka1 Fue1 reprocessing plant; 1984(January - December)

Iwai, Makoto; Akutsu, Ken*; Ishida, Junichiro; ; ; ; Hayashi, Naomi*; Asano, Tomohiro

PNC TN844 85-07, 145 Pages, 1985/02

PNC-TN844-85-07.pdf:4.71MB

This report presents current information from the environmental protection section, Tokai works, PNC on the radiation monitoring around the reprocessing plant during 1984. The report consists of general interpretive report on the results, individual interpretive reports and maximum radiation dose which may be received by hypothetical inhabitants, caused by discharge of radioactivity into both marine and terrestrial environments. Subsequent supplements include tabulations of results including meteorological observations and radioactivity measurements on discharge effluent from the plant. The environmental radiation monitoring around the Tokai reprocessing plant has been performed since 1975 based on the safety standard of the plant.

Research on geosphere stability for long-term isolation of radioactive waste, Provenance analysis technique, 2; Examination of provenance analysis index by petrologocal and mineralogical approaches

Ueki, Tadamasa; Shimizu, Mayuko; Sano, Naomi; Yonaga, Yusuke

no journal, , 

no abstracts in English

Provenance analysis based on quick quantification of heavy minerals using EPMA

Shimizu, Mayuko; Sano, Naomi; Ueki, Tadamasa; Yonaga, Yusuke; Niwa, Masakazu

no journal, , 

no abstracts in English

Provenance analysis using EPMA, case study of Horonobe area in Hokkaido

Yonaga, Yusuke; Sano, Naomi*; Amamiya, Hiroki*; Niwa, Masakazu; Yasue, Kenichi*

no journal, , 

no abstracts in English

Estimation of provenance rocks of the Toki gravel beds, the Tokai Group based on EPMA analyses of the heavy minerals

Shimizu, Mayuko; Sano, Naomi; Yasue, Kenichi; Shibata, Kenji*; Niwa, Masakazu; Suzuki, Kazuhiro

no journal, , 

no abstracts in English

Low-temperature thermochronology of the Izu collision zone, central Japan; Implications for mountain building at an active arc-arc collision zone

Sueoka, Shigeru; Kobayashi, Yumi*; Fukuda, Shoma; Kohn, B. P.*; Yokoyama, Tatsunori; Sano, Naomi*; Hasebe, Noriko*; Tamura, Akihiro*; Morishita, Tomoaki*; Tagami, Takahiro*

no journal, , 

Multi-system thermochronometries were applied to the Izu collision zone, an active arc-arc collision zone in the central Japan, in order to reveal the mountain formation process. Nine granitic samples yielded zircon U-Pb ages of 10.2-5.8 Ma (n = 2), apatite (U-Th)/He ages of 42.8-2.6 Ma (n = 7), and apatite fission-track (AFT) ages of 44.1-3.0 Ma (n = 9). Thermal inversion analyses based on the AFT data suggest rapid cooling events at ca 5 Ma and 1 Ma in the collision zone and no such thermal/tectonic effect out of the zone. The Kanto Mountains are thought to be uplifted domally associated with the collision of the Tanzawa Block at ca 5 Ma. The Minobu Mountains and possibly the adjacent mountains could be uplifted by the collision of the Izu Block at ca 1 Ma. Mountain formation in the Izu collision zone is mainly controlled by the collisions of crustal blocks of the Izu-Bonin Arc and motional change of the Philippine Sea plate.