Thermal characteristics of slab fluid in Hongu area, southwest Japan; Insights form thermochronology and fluid inclusion analyses

Sueoka, Shigeru; Kanno, Mizuho; Kawamura, Makoto; Niwa, Masakazu; Iwano, Hideki*; Danhara, Toru*

no journal, , 

no abstracts in English

Constraining timing of thrust activity within the Nobeoka Thrust, SW Japan

Zwingmann, H.*; Niwa, Masakazu; Yamaguchi, Asuka*; Fujimoto, Koichiro*; Todd, A.*

no journal, , 

Studies of the thermal, mechanical and hydrothermal effects of Nobeoka drilling core samples indicate distinctive changes in the Illite crystallinity between the footwall, main fault zone and hanging wall. Detailed illite crystallinity investigations of the core samples provide a unique framework to constrain timing of authigenic illite formation within an ancient tectonic boundary thrust system. This pilot study investigates timing of thrust formation by dating of authigenic illite (2 micron fractions) separated from 2 fresh non- weathered fault core, 3 footwall and 2 hanging wall core samples from the Nobeoka drilling core collected over a depths range of 80 to 30 m below ground surface. The obtained K-Ar ages will be discussed within the geological background of an ancient tectonic boundary thrust system.

Systematization from case studies of natural phenomena to impacts assessment on a HLW geological disposal

Kawamura, Makoto; Ishimaru, Tsuneari; Niwa, Masakazu; Komatsu, Tetsuya

no journal, , 

Regarding the selection of the suitable geological environment for geological disposal, not only the evaluation of the activity of the natural phenomena that are currently occurring, but also the prediction of the long-term occurrence and transition of natural phenomena beyond tens of thousands of years after disposal, and It is necessary to properly evaluate the impact on geological environmental conditions. In conducting an appropriate impact assessment, an impact assessment model and scenario will be established. In order to ensure their credibility, it is necessary to clarify the validity of their scientific validity based on the results of case studies. We devised an argument diagram and tried to organize the flow of information. As a result, it was possible to clarify the research contents and results information on necessary natural phenomena and geological environmental conditions for the validity of the set issues, and to clarify the flow of results information for constructing conceptual models and scenarios. In addition, we obtained the prospect of objective judgment on the validity of the evaluation scenario constructed based on the conceptual model.

Distribution map of erosion rates on timescales of 10 - 10 years in the Japanese Islands

Hiura, Yuki; Komatsu, Tetsuya; Sueoka, Shigeru; Kitamura, Yo*; Sanga, Tomoji*

no journal, , 

Distribution map of erosion rates on geological timescales should be prepared to evaluate the long-term stability of geological environments. Previous distribution maps of erosion rates were constructed based on deposition rates in artificial dams on multi-decadal timescales. This study aims to construct a new distribution map of erosion rates on timescales of 10 - 10 years by using reported data derived from terrestrial cosmogenic nuclide (TCN) methods. This study presents the method for constructing the new distribution map of erosion rate and the results of comparing it with the previous one.

Reaction and alteration of mudstone with cement pore fluids

Bateman, K.; Amano, Yuki; Tachi, Yukio

no journal, , 

Visualization of a high-strain shear zone based on a field survey for minor faults; A Case study of southern Kyushu, Japan

Goto, Akira; Shimada, Koji; Niwa, Masakazu; Terusawa, Shuji*

no journal, , 

Owing to a nationwide GNSS network installed since mid-1990s, high-strain shear zone with a sinistral strike-slip was identified in southern Kyushu. There have had large earthquakes in this area such as the 1997 Northwestern Kagoshima Earthquake, however, any seismogenic faults associated with these earthquakes or active faults with strike-slip tectonic landforms had not been previously recognized at the surface. Mesoscale fault zones with clayey gouge and cataclasite are rare in the study area (northwestern Kagoshima (2216 km)). Instead, minor faults cutting bedding planes and deformation structures subparallel to the bedding, suggesting the formation clearly after the accretion of the Shimanto accretionary complex, are commonly observed. Slip directions can be examined from striations along the minor faults. Based on orientation data of these striations, we applied stress tensor inversion techniques to elucidate stress states. Our field survey revealed an occurrence of the E-W trending zone of 2 km wide showing a stress state consistent with the sinistral high-strain shear zone (NE-SW compression and NW-SE extension). This study can contribute to one of helpful approaches to examine potential future activities of faults (or shear zones) without clear tectonic landforms.

Constraining thermal/denudation histories in the last 0.1 Myr using multi-OSL-thermochronometry applied to samples from deep boreholes; Case studies in the Japanese Islands

Ogata, Manabu; King, G.*; Herman, F.*; Sueoka, Shigeru; Yamada, Ryuji*; Omura, Kentaro*

no journal, , 

no abstracts in English

An Attempt to estimate the migration pathway of slab-derived fluid using shear wave splitting analysis

Hiratsuka, Shinya; Asamori, Koichi; Saiga, Atsushi

no journal, , 

no abstracts in English

Trial of domain segmentation of granite based on fracture orientations using Dip Azimuth Vector plot

Terusawa, Shuji*; Shimada, Koji

no journal, , 

The Dip Azimuth Vector plots used in resource exploration was utilized to visualize the dominant fracture direction trends at each depth section of borehole data taken from the Monju site. This procedure is one of the domain analysis method of granite. Domain boundaries are intersections of the two dominant fracture orientations providing pipe-like flow paths of groundwater. So, utilization of geological data accumulated at the Monju in this way, contributes application for geological survey for disposal of HLW as well as ground safety assessment for large earthquakes.

Long-term warming effect on soil carbon fluxes in a red pine forest in Tsukuba

Teramoto, Munemasa*; Liang, N.*; Jiye, Z.*; Koarashi, Jun; Kondo, Toshiaki*; Atarashi-Andoh, Mariko; Aramaki, Takafumi*; Zhao, X.*

no journal, , 

Forest soils are a large source for CO and sink for CH. Understanding long-term response of these soil carbon fluxes to warmer environment is the key to mitigation and adaptation for future climate change. To examine the long-term response of CO flux to global warming in Asian monsoon forests, we set multi-channel automated chamber measurement system in a red pine forest in Tsukuba. Half of the chambers were artificially warmed by infrared heaters. Recently, we started continuous measurement of soil CH flux using a control unit with CH analyzer. Results showed that soil temperature is the primary factor controlling soil CO fluxes, whereas soil moisture is the main factor controlling soil CH uptake in our study site.