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Journal Articles

Discrimination between active and non-active faults based on the chemical composition of fault gouge; An Attempt using linear discriminant analysis

Tateishi, Ryo*; Shimada, Koji; Shimizu, Mayuko; Ueki, Tadamasa*; Niwa, Masakazu; Sueoka, Shigeru; Ishimaru, Tsuneari

Oyo Chishitsu, 62(2), p.104 - 112, 2021/06

We attempted to discriminate between active and non-active faults by linear discriminant analysis using the chemical composition data of fault gouges in Japan, and then examined the elements that represent the difference between them and better discriminants. As a result, the multiple discriminants obtained could discriminate between them with high probability. In addition, the generalization performance of these discriminants is discussed, and the discriminants that can be expected to have high discriminant performance for unknown samples are presented. Also, from the combination of elements common to these discriminants, we narrowed down the number of elements that represent the difference between active and non-active faults to 6, and showed that the combination of TiO$$_{2}$$ and Sr contributing the most to the discrimination. The method applied in this study is an innovative one that can discriminate the activity by chemical analysis of fault rocks that are universally present in the bedrock.

Journal Articles

K-Ar ages of an andesitic parallel dike swarm in the Takane area, Takayama City, Gifu Prefecture, Central Japan

Niwa, Masakazu; Ueki, Tadamasa*; Hoshi, Hiroyuki*; Sugisaki, Yuichi*; Yagi, Koshi*; Tozawa, Terumasa

Chishitsugaku Zasshi, 126(9), p.543 - 548, 2020/09

A large number of paleomagnetic and chronological studies have contributed to the elucidation of the early Miocene clockwise rotation of Southwest Japan associated with the major opening of back-arc basins of the Japan Sea. Paleomagnetic data from an andesitic parallel dike swarm in the Takane area, Takayama City, Gifu Prefecture, Central Japan, were previously reported, showing the easterly deflection of the observed magnetization direction compared to an early Miocene expected paleomagnetic direction. This must represent the clockwise rotation during the opening of the Japan Sea, if the dike swarm was intruded before the opening event. Here, we report new K-Ar hornblende ages from an andesite dike of the dike swarm. These ages are statistically indistinguishable, indicating emplacement of the dike swarm before the clockwise rotation.

JAEA Reports

Study on sample description, composition, and preparation for dating of altered volcanic rocks

Niwa, Masakazu; Ueki, Tadamasa*; Hoshi, Hiroyuki*; Sugisaki, Yuichi*

JAEA-Research 2020-003, 33 Pages, 2020/07

JAEA-Research-2020-003.pdf:5.69MB

Ages of volcanic rocks are helpful information to understand the impact of volcanism concerning a site characterization and a safety assessment for geological disposal. In this study, mineralogical and geochemical data of altered volcanic rocks were collected using a polarizing microscope, X-ray diffractometer, X-ray fluorescence spectrometer, X-ray analytical microscope, and electron probe microanalyzer, to select targets suitable for reliable K-Ar dating. In addition, sample preparation procedures such as freeze-thawing and HCl treatment were examined to concentrate unaltered plagioclase which is one of major phenocrysts in volcanic rocks. These data and procedures were compiled in this report.

JAEA Reports

Annual report for research on geosphere stability for long-term isolation of radioactive waste in fiscal year 2017

Ishimaru, Tsuneari; Ogata, Nobuhisa; Shimada, Akiomi; Asamori, Koichi; Kokubu, Yoko; Niwa, Masakazu; Watanabe, Takahiro; Saiga, Atsushi; Sueoka, Shigeru; Komatsu, Tetsuya; et al.

JAEA-Research 2018-015, 89 Pages, 2019/03

JAEA-Research-2018-015.pdf:14.43MB

This annual report documents the progress of research and development (R&D) in the 3rd fiscal year during the JAEA 3rd Mid- and Long-term Plan (fiscal years 2015-2021) to provide the scientific base for assessing geosphere stability for long-term isolation of the high-level radioactive waste. The planned 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. In this report, the current status of R&D activities with previous scientific and technological progress is summarized.

Journal Articles

Zircon U-Pb and Fission-track ages for the Ohta Tephra in the Pliocene Tokai Group, Central Japan

Ueki, Tadamasa; Niwa, Masakazu; Iwano, Hideki*; Danhara, Toru*; Hirata, Takafumi*

Chishitsugaku Zasshi, 125(3), p.227 - 236, 2019/03

no abstracts in English

Journal Articles

Provenance identification based on EPMA analyses of heavy minerals; Case study of the Toki Sand and Gravel Formation, central Japan

Shimizu, Mayuko; Sano, Naomi; Ueki, Tadamasa; Komatsu, Tetsuya; Yasue, Kenichi*; Niwa, Masakazu

Island Arc, 28(2), p.e12295_1 - e12295_13, 2019/03

 Times Cited Count:1 Percentile:11.99(Geosciences, Multidisciplinary)

no abstracts in English

JAEA Reports

Petrographic data of silicic igneous rocks in the Tono area, central Japan

Ueki, Tadamasa; Niwa, Masakazu

JAEA-Data/Code 2018-005, 94 Pages, 2018/08

JAEA-Data-Code-2018-005.pdf:15.6MB

Mountain development has an influence on long-term changes of uplift, erosion, and groundwater flow related to change in hydraulic gradient. Provenance analysis is one of promising geological methods to understand origin and formation process of mountains. Case study in the Tono area, central Japan has been done for research and development of individual technique to estimate a provenance. In this report, petrological descriptions by meso- and microscopic observations and elemental distributions using scanning X-ray analytical microscope of basement rocks (silicic igneous rocks) from the study area were compiled.

JAEA Reports

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.

Journal Articles

Modal analysis using scanning X-ray analytical microscope and image processing and analyzing softwares

Ueki, Tadamasa; Niwa, Masakazu

Chishitsugaku Zasshi, 123(12), p.1061 - 1066, 2017/12

Conventional point counting method for modal analysis is time-consuming, and often affected by measurer's skill and subjective view on the determination of minerals. We introduce the alternate method using scanning X-ray analytical microscope and image processing and analyzing softwares. This method is simple and not affected by measurer's skill and subjective view. By using this method for thin sections or polished slabs of granitic rocks, we provided clear images showing mineral distributions and obtained objective data of modal compositions efficiently and quickly.

JAEA Reports

Observed and analyzed data for clay veins in granite

Ueki, Tadamasa; Tanabe, Hiroaki*; Niwa, Masakazu; Ishimaru, Tsuneari; Shimada, Koji

JAEA-Data/Code 2016-010, 292 Pages, 2016/09

JAEA-Data-Code-2016-010.pdf:76.12MB

Occurrence of recent activity of faults is often evaluated based on displacements of subsurface sediments covering the faults. However, this evaluation is not applicable for faults that occur where subsurface sediments are not found. In this study, mesoscopic description in a field, microscopic observation using thin sections, chemical composition mapping for polished slabs, X-ray diffraction analysis, particle size distribution analysis, and detailed analysis for quartz fragments (scanning electron microscopy and measurement of electron spin resonance signals) were carried out for clay veins in order to contribute a development of evaluation of fault activity. This Data/Code reports the results of these observation and analyses.

Oral presentation

Microscopic structures of mineral fragments from faults and clay veins in granite

Niwa, Masakazu; Tanabe, Hiroaki; Ishimaru, Tsuneari; Shimada, Koji; Ueki, Tadamasa*

no journal, , 

Fault gouge in granitic rocks is commonly clay-rich, as a result of fracturing and comminution caused by concentrated deformation and displacement, and subsequent retrograde hydration reactions. In some cases, fractures filled with clay minerals described as clay veins occur due to hydrothermal alteration. The hydrothermal clay veins associated with secondary shearing through old geologic time, or with secondary non-tectonic slips are often similar in appearance to typical fault gouges in active faults. Thus precise discrimination of active fault gouges from inactive clay veins is important for avoiding misleading estimates of seismic hazard. In this study, in-depth investigations were carried out on clay vein samples from the Hiroshima Granite, central Japan.

Oral presentation

Geological survey on faults and clay veins in granite

Tanabe, Hiroaki; Niwa, Masakazu; Ishimaru, Tsuneari; Shimada, Koji; Ueki, Tadamasa*

no journal, , 

An outcrop of an active fault geological feature gap and a heat water deterioration vein paid attention to clay vein of granite, and conducted a field survey for the purpose of the field sample extraction offered to a study of the material science-like value and judgment technique about the granite body you can expect to be distributed from documents in the past and research reports of existence, etc.. I'll report on those outcrop distribution situations by an announcement.

Oral presentation

Modal analysis using X-ray analytical microscope and image processing and analyzing softwares

Ueki, Tadamasa; Niwa, Masakazu

no journal, , 

no abstracts in English

Oral presentation

Case study of provenance analysis based on petrography

Ueki, Tadamasa; Shimizu, Mayuko; Niwa, Masakazu; Yasue, Kenichi

no journal, , 

no abstracts in English

Oral presentation

Estimation of provenance rocks based on EPMA analyses of the heavy minerals; A Case study of Byobuyama fault

Shimizu, Mayuko; Sano, Naomi; Ueki, Tadamasa; Yasue, Kenichi; Niwa, Masakazu; Suzuki, Kazuhiro

no journal, , 

no abstracts in English

Oral presentation

Provenance analysis to understand formation and development of mountains

Niwa, Masakazu; Shimizu, Mayuko; Yasue, Kenichi; Nishimura, Shusaku; Amamiya, Hiroki; Ueki, Tadamasa; Horiuchi, Yasuharu

no journal, , 

Uplift and associated denudation of mountains affect hydraulic gradient and groundwater flow path. In the case of a safety assessment for geological disposal of radioactive wastes, uplift and denudation will be examined in terms of nuclide migration driven by deep groundwater as well as potential exposure of repositories. Provenance analysis based on sedimentological, petrological, mineralogical and geochemical approaches in downstream area is often helpful for understanding onset times and processes of uplift and associated denudation of mountains in upstream area. In this study, quick quantification analysis for heavy minerals and measurement of electron spin resonance signal for quartz to estimate provenance rocks, and paleo-current analysis using magnetic anisotropy of susceptibility for fine sand were developed.

Oral presentation

Examination of provenance analysis index by petrological and mineralogical approaches

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

no journal, , 

no abstracts in English

Oral presentation

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

Oral presentation

Identification of provenance rocks based on EPMA analyses of heavy minerals

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

no journal, , 

31 (Records 1-20 displayed on this page)