Initialising ...
Initialising ...
Initialising ...
Initialising ...
Initialising ...
Initialising ...
Initialising ...
Sakai, Toru*; Kametaka, Masao*; Aoki, Kazuhiro; Shimada, Koji; Takagi, Hideo*
Chishitsugaku Zasshi (Internet), 130(1), p.89 - 109, 2024/04
Shear planes are formed in various orientations within fault fracture zones. The sense of shear on each shear plane can be determined from the composite planar fabrics developed around it. However, it is not possible to distinguish whether all the shear planes in a fault fracture zone were formed during the same stage of motion by observations alone, because of the scarcity of chronological data. As such, we attempted to determine the kinematic and stress histories of the Shionohira and Kuruma faults by using both observations of composite planar fabrics and stress inversion analysis. As a result, we identified five stages of motion on the Shionohira Fault and two stages of motion on the Kuruma Fault. The chronological data are not sufficient to constrain the timing of the stages, but the reconstructed histories are consistent with the paleostress fields and tectonic activity around these faults, as determined in previous studies. Although the reconstructed stress history depends on the density of fault-slip data from the measurement area, this method is effective for investigating the formation mechanisms of fault fracture zones.
Yamada, Kunimi; Hanamuro, Takahiro; Tagami, Takahiro*; Shimada, Koji; Takagi, Hideo*; Yamada, Ryuji*; Umeda, Koji
Journal of Asian Earth Sciences, 45(2), p.17 - 23, 2012/02
Times Cited Count：5 Percentile：11.19(Geosciences, Multidisciplinary)no abstracts in English
Takagi, Hideo*; Miwa, Shigenori*; Yokomizo, Yoshiyuki*; Nishijima, Kei*; Enjoji, Mamoru*; Mizuno, Takashi; Amano, Kenji
Chishitsugaku Zasshi, 114(7), p.321 - 335, 2008/07
Based on the 3-D orientations of intracrystalline healed, sealed and open extension microcracks in quartz grains in the Late Cretaceous Toki Granite, we discuss the paleostress field and the history of microcracking combining the microthermometry of fluid inclusions in healed microcracks and sealing material identification in sealed microcracks. Twenty one oriented samples are collected mainly from the DH-15 core (240-1000 mabh) drilled by Japan Atomic Energy Agency (JAEA) and additionally from five outcrops in the Tono region. 3-D orientations of healed microcracks indicate the 
orientation of N-S to NW-SE in almost all sites, whereas those of sealed and open microcracks indicate the dominant orientation of E-W. Two or three orthogonal sets of microcracks are common in both healed and sealed microcracks. The formation of these sets can be attributed to the switch of principal stress axis due to stress release just after the crack formation. Healed microcracks probably reflect more regional paleostress field because of consistency of the orientations than the case of sealed and open microcracks that show rather scattering orientations. N-S to NW-SE trending healed microcracks are formed around 60 Ma on the basis of K-Ar biotite ages of the Toki Granite and formation temperature (c. 300-400
C) of fluid inclusions estimated from microthermometry in the case of intrusion depth (3.5 km=100 MPa) of the Toki Granite. Thus the orientation trended NW-SE after the restoration of clockwise rotation of SW Japan at c. 15 Ma. Following the healed microcrack formation, E-W trending high-angle sealed microcracks filled with carbonate mineral are formed. Open microcracks presumably formed at near-surface at the last stage of sealed microcrack formation after c. 20 Ma before the Mizunami Group deposited unconformably on the granite.
Miwa, Shigenori*; Takagi, Hideo*; Nishijima, Kei*; Yokomizo, Yoshiyuki*; Enjoji, Mamoru*; Mizuno, Takashi
no journal, ,
no abstracts in English
Yamada, Kunimi; Takagi, Hideo*; Tagami, Takahiro*; Danhara, Toru*
no journal, ,
Taki pseudotachylyte first found along the MTL was formed after mylonitization of the Hatai Tonalite under amphibolite to greenschist facies conditions, and had been post-dated by cataclasis. We dated some zircons from the mylonited Tonalite around the pseudotachylyte using the (U-Th)/He method, the age corresponds approximately to the FT ages of the pseudotachylyte, not the Tonalite. This suggests that the ambient temperature for generating the pseudotachylyte was higher than the closure temperature of ZHe, and this is consistent with cataclasis temperature. In this case we can not say the age of the pseudotachylyte, however, we can constrain something for the age and cooling-denudation history of this fault. Now we continue to date zircons from the pseudotachylyte.
Yamada, Kunimi; Hanamuro, Takahiro; Tagami, Takahiro*; Takagi, Hideo*; Shimada, Koji; Umeda, Koji; Iwano, Hideki*; Danhara, Toru*
no journal, ,
Japan Atomic Energy Agency have jointly set up the system of the (U-Th)/He dating in cooperation with Kyoto University and National Institute for Earth Sciences and Disaster Prevention. Through this two years, helium extraction machine using an electronically-cooled diode laser, micro crusible system using XRF bead sampler and uranium and thorium quantification procedure without artificial spikes are developed. Now we produce new ages of some age known samples. At the present stage, the accuracy and precision are roughly 20 and 10%, respectively, using the age standard zircon from the Fish Canyon Tuff (FC3). In the presentation, we will introduce our systems and the ages detailedly.
Yamada, Kunimi; Hanamuro, Takahiro; Tagami, Takahiro*; Shimada, Koji; Takagi, Hideo*; Iwano, Hideki*; Danhara, Toru*; Umeda, Koji
no journal, ,
no abstracts in English
Yamada, Kunimi; Hanamuro, Takahiro; Tagami, Takahiro*; Shimada, Koji; Takagi, Hideo*; Iwano, Hideki*; Danhara, Toru*; Umeda, Koji
no journal, ,
no abstracts in English
Yamada, Kunimi; Hanamuro, Takahiro; Shimada, Koji; Umeda, Koji; Tagami, Takahiro*; Takagi, Hideo*; Yamada, Ryuji*
no journal, ,
no abstracts in English
Iwamori, Akiyuki*; Takagi, Hideo*; Shimada, Koji; Asahi, Nobutaka*; Sugimori, Tatsuji*; Sasaki, Toshinori*; Aiyama, Kotaro*
no journal, ,
no abstracts in English
Iwamori, Akiyuki*; Ogita, Yasuhiro; Shimada, Koji; Tateishi, Ryo*; Takagi, Hideo*; Ota, Toru*; Kanno, Mizuho*; Wada, Shinya*; Ono, Akihiro*; Otsuka, Yoshiharu*
no journal, ,
We investigated the W value, which is an index showing the progress of weathering, for the fault rocks in the Kojak granite distributed in the eastern Wakasa area. The W value represents the contribution due to weathering calculated from the chemical composition, and along with the M value (contribution of the mafic component) and F value (contribution of the felsic component), a triangular diagram of M + F + W = 100% showing trends from protolith to fault rocks (cataclasite or fault gouge) can be drown. We also investigated on the fault at the geological boundary between the Kojaku granite and the Mino-Tamba metabasalt, and on the difference in characteristics from the fault rock in the Kojaku granite. Granite protolith has an F value of 94.2% and W value of 4.9%, and the fault rock sample has an M value of about 3% regardless of whether it is an active fault or an inactive fault. As weathering progresses, the F value decreases and the W value increases. Metabasalt has an M value of 88.2% and a W value of 6.6%, and the cataclasite has an almost constant F value. As weathering progresses, the M value decreases and the W value increases. Some of the F value increases with the increase of the W value, which is consistent with the contamination of granite-origin quartz fragments found in the basaltic fault gouge. As a result of examination, it was confirmed that Na
O and CaO have a great influence on the increase and decrease of the W value.
Sakai, Toru*; Kametaka, Masao*; Aoki, Kazuhiro; Shimada, Koji; Takagi, Hideo*
no journal, ,
no abstracts in English
