2:30 PM - 3:00 PM
[SCG54-04] Significance of geochronology and thermochronology on geological disposal: recent studies and future’s prospects
★Invited Papers
Keywords:natural phenomena, geochronology, thermochronology, geological disposal
For the safety assessment of geological disposal of high-level radioactive waste, it is essential to evaluate the influence of natural phenomena such as volcanic/hydrothermal activity, fault movement, uplift/erosion, and climate/sea level change. The evaluation is generally based on the records of these natural phenomena from the past to the present. Thus, chronological studies play a very important role in the evaluation. In this presentation, recent research outcomes and future’s prospects by JAEA on geochronology and thermochronology are showcased.
Concerning an estimation of uplift/erosion rate, the following techniques were proposed: an approach using multi-OSL-thermometry of K-feldspar from deep borehole core (Ogata et al., 2002, EPSL), examination based on the combination of Al-in-hornblende geobarometry and U–Pb zircon dating (Kawakami et al., 2021, IAR; Suzuki et al., 2022, IAR), and applications of feldspar IRSL dating (Ogata et al., 2021, Quaternary Research of Japan) and depth profile of terrestrial cosmogenic nuclides to an estimation of emergence age of a terrace. In order to contribute to the evaluation of hydrothermal activity, fluid-inclusion and thermochronometric analyses to detect thermal anomalies around hydrothermal veins were examined (Sueoka et al., submitted). In addition, several geochronological studies were conducted to understand history of fault activity, including case studies for inland active faults in central Japan (Zwingmann et al., in prep.).
These recent researches can contribute to the development of investigation methodology for the site selection/design and safety assessment on the geological disposal project. However, further accumulation of geochronological and thermochronological studies for a wide spatial and temporal range and for various geological environment are still needed for the reliable evaluation of future’s risk on natural phenomena.
This study was funded by METI, Japan as part of its R&D supporting program titled “Establishment of Advanced Technology for Evaluating the Long-term Geosphere Stability on Geological Disposal Project of Radioactive Waste (JPJ007597) (Fiscal Year 2018-2022)”.
Concerning an estimation of uplift/erosion rate, the following techniques were proposed: an approach using multi-OSL-thermometry of K-feldspar from deep borehole core (Ogata et al., 2002, EPSL), examination based on the combination of Al-in-hornblende geobarometry and U–Pb zircon dating (Kawakami et al., 2021, IAR; Suzuki et al., 2022, IAR), and applications of feldspar IRSL dating (Ogata et al., 2021, Quaternary Research of Japan) and depth profile of terrestrial cosmogenic nuclides to an estimation of emergence age of a terrace. In order to contribute to the evaluation of hydrothermal activity, fluid-inclusion and thermochronometric analyses to detect thermal anomalies around hydrothermal veins were examined (Sueoka et al., submitted). In addition, several geochronological studies were conducted to understand history of fault activity, including case studies for inland active faults in central Japan (Zwingmann et al., in prep.).
These recent researches can contribute to the development of investigation methodology for the site selection/design and safety assessment on the geological disposal project. However, further accumulation of geochronological and thermochronological studies for a wide spatial and temporal range and for various geological environment are still needed for the reliable evaluation of future’s risk on natural phenomena.
This study was funded by METI, Japan as part of its R&D supporting program titled “Establishment of Advanced Technology for Evaluating the Long-term Geosphere Stability on Geological Disposal Project of Radioactive Waste (JPJ007597) (Fiscal Year 2018-2022)”.