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Yuguchi, Takashi*; Yagi, Koshi*; Sasao, Eiji; Nishiyama, Tadao*
Heliyon (Internet), 7(4), p.e06750_1 - e06750_9, 2021/04
Times Cited Count：1 Percentile：18.67(Multidisciplinary Sciences)Our methodology and interpretations provide new insight for K-Ar geochronology in hydrothermal microcline within altered plagioclase in a granitic pluton. Our methodology employs a two-step separation process consisting of (1) plagioclase extraction from the rock sample and (2) separation of the hydrothermal microcline from the plagioclase, giving precise determination of microcline powders in K-Ar geochronology. This tighter constraint should provide the ability to better unravel thermal and age histories in granite subject to multi-step alteration processes and complex thermal histories.
Yuguchi, Takashi*; Ishibashi, Kozue*; Sakata, Shuhei*; Yokoyama, Tatsunori; Ito, Daichi*; Ogita, Yasuhiro; Yagi, Koshi*; Ono, Takeshi*
Lithos, 372-373, p.105682_1 - 105682_9, 2020/11
Times Cited Count：1 Percentile：9.85(Geochemistry & Geophysics)Simultaneous determination of zircon U-Pb age and titanium concentration for a single analysis spot gives both the crystallization age and temperature. The crystallization age and temperature pairs in granitic zircons map the time-temperature (
) path of granitic magma before its solidification. In laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS) analysis, it is challenging to quantitatively analyse a low level of titanium concentration. This study employed two approaches using a Quadrupole mass spectrometer equipped with a collision/reaction cell (CRC). The methods were applied to zircon samples of the Kurobegawa granite (KRG), the Okueyama granite (OKG), the Toki granite (TKG), and the Tono plutonic complex (TPC) and provided U-Pb ages and titanium concentrations consistent with previous studies. The crystallization ages and temperatures collected from individual analysis spots of zircon samples in the KRG, OKG, TKG, and TPC are plotted in the diagrams and enable us to characterize the rapid cooling paths at thermal conditions of zircon crystallization at the sampling sites.
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.
Yuguchi, Takashi*; Shobuzawa, Kaho*; Ogita, Yasuhiro*; Yagi, Koshi*; Ishibashi, Masayuki; Sasao, Eiji; Nishiyama, Tadao*
American Mineralogist, 104(4), p.536 - 556, 2019/04
Times Cited Count：15 Percentile：76.35(Geochemistry & Geophysics)This study describes the plagioclase alteration process with a focus on the role of micropores, mass transfer and reaction rate in the Toki granitic pluton, central Japan. The plagioclase alteration process involves albitization, K-feldspathization, and the formation of illite, calcite, fluorite and epidote. Such secondary minerals of hydrothermal origin in plagioclase within granitic rocks record the chemical characteristics of the hydrothermal fluid. Our results highlight (1) the nature of micropores such as distribution and volume in plagioclase, (2) the reaction nature of plagioclase alteration inferred by petrography and chemistry, (3) the physical conditions including alteration age and temperature, (4) the sequential variations of the fluid chemistry and (5) the mass transfer rate and reaction rate in the plagioclase alteration.
Sueoka, Shigeru; Shimada, Koji; Ishimaru, Tsuneari; Danhara, Toru*; Iwano, Hideki*; Yagi, Koshi*
Chigaku Zasshi, 127(6), p.795 - 803, 2018/12
no abstracts in English
Sueoka, Shigeru; Umeda, Koji; Yasue, Kenichi; Niwa, Masakazu; Shimada, Koji; Ishimaru, Tsuneari; Danhara, Toru*; Iwano, Hideki*; Yagi, Koshi*
Chigaku Zasshi, 125(2), p.201 - 219, 2016/04
We applied multi-system thermochronology to the Tsuruga body of the Kojaku granite to constrain the cooling/denudation history of the Tsuruga area. Based on the thermochronometric results and other data, we reconstructed the cooling and denudation histories of the Tsuruga body as below: (1) the Tsuruga body intruded at c.a. 68 Ma at the depth of 4-5 km, (2) rapidly cooled down to c.a. 200
C by heat conduction within a few million years or less, and (3) slowly cooled due to peneplanation during the Cenozoic. This cooling/denudation history is consistent with the observations that cataclasite and fault gouge are dominant in the crush zones of the Tsuruga body, that similar slow cooling histories over the Cenozoic are estimated in the surrounding areas based on thermochronometric ages, and that the amount of denudation in the last few million years in the Tsuruga area is inferred at less than several hundred meters from the elevations of the uplifted peneplains.
Utsumi, Wataru; Funakoshi, Kenichi*; Yagi, Naoto*; Urakawa, Satoru*; Otaka, Osamu*; Katsura, Tomoo*; Irifune, Tetsuo*; Inoue, Toru*; Uchida, Takeyuki*
Ganseki Kobutsu Kagaku, 30(2), p.100 - 101, 2001/03
no abstracts in English
Yuguchi, Takashi*; Shobuzawa, Kaho*; Ogita, Yasuhiro*; Yagi, Koshi*; Ishibashi, Masayuki; Sasao, Eiji; Nishiyama, Tadao*
no journal, ,
This study presents the plagioclase alteration process with a focus on the role of micropores, mass transfer and reaction rate in the Toki granitic pluton, central Japan. The plagioclase alteration process involves an albitization, K-feldspathization and the formation of illite, calcite, fluorite and epidote. Such secondary minerals of hydrothermal origin in plagioclase within granitic rocks record the chemical characteristics of the hydrothermal fluid. Our results highlight (1) the nature of micropores such as distribution and volume in plagioclase, (2) the reaction nature of plagioclase alteration inferred by petrography and chemistry, (3) the physical conditions including alteration age and temperature, (4) the sequential variations of the fluid chemistry and (5) the mass transfer rate and reaction rate in the plagioclase alteration.
Ishibashi, Kozue*; Sakata, Shuhei*; Yokoyama, Tatsunori; Ito, Daichi*; Ogita, Yasuhiro; Yagi, Koshi*; Ono, Takeshi*; Yuguchi, Takashi*
no journal, ,
no abstracts in English
Ito, Daichi*; Ishibashi, Kozue*; Sakata, Shuhei*; Yokoyama, Tatsunori; Ogita, Yasuhiro; Yagi, Koshi*; Ono, Takeshi*; Yuguchi, Takashi*
no journal, ,
no abstracts in English
Yuguchi, Takashi*; Ito, Daichi*; Yokoyama, Tatsunori; Sakata, Shuhei*; Suzuki, Satoshi*; Ogita, Yasuhiro; Yagi, Koshi*; Imura, Takumi*; Motai, Satoko*; Ono, Takeshi*
no journal, ,
This study proposes a new method for elucidating zircon growth processes in the Okueyama granitic pluton, Kyushu, Japan. Our method, which combines 3D growth patterns, U-Pb ages, titanium concentration, and Th/U ratios, contributes to the petrology and mineralogy to understand the growth of zircon crystals within a magma chamber. Simultaneous determination of zircon U-Pb ages and titanium concentrations for the granite gives the variations in the temporal and thermal conditions during zircon growth, thus, developing a t-T history of the granitic magma before its solidification. The simultaneous determination of zircon U-Pb ages and Ti concentrations in the granite also enable us to associate the Th/U ratio with the crystallization temperature. Therefore, the decrease in zircon Th/U ratios as decreasing the temperature indicates the progression of fractional crystallization as the cooling of the magma chamber.
