著者

Sota NIKI Kenta YOSHIDA Hikaru SAWADA Ryosuke OYANAGI Takafumi HIRATA

出版者

Japan Association of Mineralogical Sciences

雑誌

Journal of Mineralogical and Petrological Sciences (ISSN:13456296)

巻号頁・発行日

vol.117, no.1, pp.210814, 2022 (Released:2022-05-18)

参考文献数

24

被引用文献数

1

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Here we first report the in situ U–Pb dating of metamorphic grossular garnet (Grs) with distinction between internal zonation textures. The studied Grs occurs in an eclogite–facies marble collected from the eastern Iratsu body of the Sanbagawa metamorphic terrane, Japan. The Grs has a patchy texture, predominantly with pure Grs cores and andradite (Adr)–rich rims formed during eclogite–facies and exhumation stages, respectively. The U–Pb ages for the Grs core and Adr–rich rim were 97 ± 10 and 106 ± 16 Ma (95% confidence level), respectively. Despite the compositional zoning formed under different P–T conditions, the U–Pb ages of the core and rim were in similar values within analytical uncertainties. This decoupling of chemical zonation and U–Pb ages implies that the U–Pb chronological signatures of rims were inherited from cores owing to the redistribution of radiogenic Pb in cores during the rim formation through fluid–mediated dissolution and reprecipitation. The Grs U–Pb age (97 ± 10 Ma) thus directly corresponds to previously reported P–T conditions of the core formation during the eclogite–facies metamorphism. This advantage of Grt petrochronology as the combination of radiometric ages obtained by in situ analysis and P–T conditions deduced from paragenesis can contribute to reconstruct reliable metamorphic histories.

著者

Kenta YOSHIDA Sota NIKI Hikaru SAWADA Ryosuke OYANAGI

出版者

Japan Association of Mineralogical Sciences

雑誌

Journal of Mineralogical and Petrological Sciences (ISSN:13456296)

巻号頁・発行日

pp.200730, (Released:2020-12-08)

被引用文献数

2

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Datolite [CaBSiO4(OH)] was discovered in an eclogite–facies calcite marble collected from the Eastern Iratsu body in the Sanbagawa metamorphic belt of central Shikoku. The marble was composed of calcite, diopside, and garnet that contained inclusions of omphacite. Enclosed in the marble is a pod composed mainly of quartz, with subordinate calcite, diopside, and garnet that has inclusions of datolite. The formation conditions of the datolite were estimated on the basis of mineral assemblage and the Raman elastic geobarometer to be approximately 400–650 °C and 0.8–1.3 GPa, which coincide with the conditions of the eclogite juxtaposition with the non–eclogite units in the Besshi district. Our study records the highest pressure–temperature conditions as the metamorphic datolite formation. Our findings provide evidence for the occurrence of B–rich fluid infiltration during the juxtaposition of eclogite unit with the non–eclogite unit in the Besshi district.

著者

Kenta Yoshida Yoshihiko Tamura Tomoki Sato Chalermrat Sangmanee Ratchanee Puttapreecha Shigeaki Ono

出版者

GEOCHEMICAL SOCIETY OF JAPAN

雑誌

GEOCHEMICAL JOURNAL (ISSN:00167002)

巻号頁・発行日

pp.GJ22011, (Released:2022-08-06)

被引用文献数

7

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The 2021 eruption of Fukutoku-Oka-no-Ba (FOB) in the northwest Pacific on 13 August 2021 produced a large volume of pumice that drifted westward for ~1300 km to the Nansei Islands, Japan, and some extent. In February 2022, pumice with similar characteristics to the FOB pumice was deposited along the Gulf of Thailand. The pumice clasts deposited in Songkhla Province, Thailand, were fine-grained with <4 cm in size and rounded. Most of the clasts consisted of clinopyroxene, plagioclase (andesine), and olivine phenocrysts in a vesiculated grey groundmass, with black-coloured spots exhibiting signatures of a basaltic magma. The whole-rock compositions of the pumice are trachytic, with 61 mass% SiO2 and 9 mass% total alkali (Na2O + K2O). The overall characteristics in the pumice from Thailand are similar to those in FOB pumice. These pumice in Thailand were from the 2021 FOB eruption, and drifted >2800 km south-westward across the South China Sea.

著者

Kenta YOSHIDA Tatsu KUWATANI Atsushi YASUMOTO Satoru HARAGUCHI Kenta UEKI Hikaru IWAMORI

出版者

Japan Association of Mineralogical Sciences

雑誌

Journal of Mineralogical and Petrological Sciences (ISSN:13456296)

巻号頁・発行日

pp.171127, (Released:2018-06-07)

被引用文献数

3

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Conventional clustering algorithms such as k–means and fuzzy c–means (FCM) cluster analysis do not fully utilize the spatial distribution information of geologic samples. In this paper, we propose GEOFCM, a new clustering method for geochemical datasets with location coordinates. A spatial FCM algorithm originally constructed for image segmentation was modified for application to a sparse and unequally–spaced dataset. The proposed algorithm evaluates the membership function of each sample using neighboring samples as a weighting function. To test the proposed algorithm, a synthetic dataset was analyzed by several hyper–parameter settings. Applying this algorithm to a geochemical dataset of granitoids in the Ina–Mikawa district of the Ryoke belt shows that samples collected from the same geological unit are likely to be classified as the same cluster. Moreover, overlapping geochemical trends are classified consistently with spatial distribution, and the result is more robust against noise addition than standard FCM analysis. The proposed method is a powerful tool to use with geological datasets with location coordinates, which are becoming increasingly available, and can help find overviews of complicated multidimensional data structure.

著者

Kenta YOSHIDA Naoki AOYAGI Ryoji KATO Takao HIRAJIMA

出版者

一般社団法人日本鉱物科学会

雑誌

Journal of Mineralogical and Petrological Sciences (ISSN:13456296)

巻号頁・発行日

vol.111, no.6, pp.398-404, 2016 (Released:2017-01-12)

参考文献数

35

被引用文献数

1 5

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Thermal structure of the Kebara Formation and its proximal areas in the western Kii Peninsula was examined by Raman spectra of carbonaceous material (RSCM) geothermometer for pelitic rocks. A mean temperature of 313 ± 5 °C is obtained for the Kebara Formation, which is comparable with that of the neighboring unit of the Mikabu belt (319 ± 5 °C). The Sanbagawa belt of the relevant area, within a few kilometers to the north of the Kebara Formation, shows a mean temperature of 285 ± 7 °C, which is slightly but evidently lower value than those of the above two units. Peak temperatures estimated from the Chichibu belt and Shimanto belt located to the south of the Kebara Formation are 289 ± 13 °C and 216 ± 24 °C, respectively. Published geochronological data of the Kebara Formation are slightly older than those of the Sanbagawa belt in the Kii Peninsula and are similar to those of the Mikabu belt in the relevant area. These two data sets (geothermometry and geochronology) suggest that the Kebara Formation is possibly correlated with the Mikabu belt, but is not coherent to the southern margin of the Sanbagawa belt in the western Kii Peninsula, in tectonic contact with each other.

著者

Kenta YOSHIDA Takao HIRAJIMA

出版者

Japan Association of Mineralogical Sciences

雑誌

Journal of Mineralogical and Petrological Sciences (ISSN:13456296)

巻号頁・発行日

vol.107, no.1, pp.50-55, 2012 (Released:2012-02-29)

参考文献数

21

被引用文献数

5 5

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Annular fluid inclusions were found in a foliation-parallel quartz vein intercalated with metapelites from the Besshi area of the Sanbagawa belt, SW Japan. The preserved “foam microstructure” of the quartz vein suggests low differential stress at high temperatures for its formation. Three types of fluid inclusions have been identified: the earliest one, FIA-I, is characterized by two phase inclusions arranged along intragranular planes and mainly composed of aqueous saline fluid and CH4 gas; FIA-II texturally comparable to FIA-I consists of CH4-N2-CO2-H2 gas phase inclusions with rare two-phase inclusions; the latest type, FIA-III, is characterized by arrangements along transgranular planes consisting of two-phase inclusions mainly composed of CH4-N2 vapor in aqueous saline fluid. Amongst them, FIA-I contains annular fluid inclusions, which are attributed to reequilibration due to a confining pressure increase, suggesting that the host rock underwent the compression after the entrapment of FIA-I. Textural observations and chemical characteristics show that FIA-I and -II were trapped during prograde or near the peak metamorphic stage, and that FIA-III was probably trapped at an early stage of the exhumation.

著者

Kenta YOSHIDA Takao HIRAJIMA

出版者

一般社団法人日本鉱物科学会

雑誌

Journal of Mineralogical and Petrological Sciences (ISSN:13456296)

巻号頁・発行日

vol.110, no.5, pp.197-213, 2015 (Released:2015-11-11)

参考文献数

49

被引用文献数

5

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Garnet with a complex compositional zoning was found from the northern edge of the Western Iratsu body in the Sanbagawa metamorphic belt of the Besshi district, southwest Japan. The studied garnet shows incipient Mn–reverse (increase) zoning from the center part and subsequent Mn–bell shape type (decrease) zoning towards the outer part, which is almost identical to the ‘Mn–caldera shaped zoning’ described by Xu et al. (1994) and Banno and Nakamura (2004). In order to display the chemical characteristics sterically, three–dimensional X–ray chemical mapping was performed for one very–coarse grain of garnet. The result clearly displays that there is a high–Mn layer with faceted euhedral shape of the garnet at the intermediate part, and that its composition continuously changes from the inside to the outside. Inclusion arrays in garnet getting across the high–Mn layer also suggest the continuous growth of the garnet. In the same sample, garnets without Mn–caldera shaped zoning are ubiquitously observed, which are relatively small in size up to 5 mm in diameter. Inclusion mineral assemblage in garnet and Raman barometry suggest the peak P–T conditions of the studied sample not having reached the eclogite facies, but being the epidote–amphibolite facies. The formation process of the ‘Mn–caldera shaped zoning’ can be best explained by the disequilibrium crystal growth under oversaturation of garnet in MnO–(MgO + FeO) binary system. Such oversaturation can be triggered by rapid heating. The finding of the remnant of rapid heating event would provide an important clue to discuss the exhumation history of the Sanbagawa metamorphic belt.

著者

Kenta Yoshida Rustam Orozbaev Takao Hirajima Akira Miyake Akira Tsuchiyama Apas Bakirov Akira Takasu Kadyrbek Sakiev

出版者

GEOCHEMICAL SOCIETY OF JAPAN

雑誌

GEOCHEMICAL JOURNAL (ISSN:00167002)

巻号頁・発行日

vol.52, no.1, pp.59-67, 2018 (Released:2018-02-02)

参考文献数

42

被引用文献数

5 5

---

Direct chemical analysis of a single fluid inclusion was conducted by micro-excavation at cryo-temperatures. A scanning electron microscope (SEM) equipped with a focused ion beam (FIB), an energy dispersive X-ray spectrometer (EDS), and a cold stage, were used to analyze the chemical composition of the sample fluid inclusion, which was trapped in the ultrahigh-pressure (UHP) talc-garnet-chloritoid schist obtained from the Makbal metamorphic complex, Kyrgyz. Conventional techniques such as microthermometry and cryo-temperature and room-temperature Raman spectroscopy enabled the detection of NaCl and CaCl2 as solute species in the fluid inclusions, as well as high salinity of 20.5 mass% CaCl2 and 1.7 mass% NaCl with the assumption of a NaCl-CaCl2-H2O ternary system. However, additional chemical analysis using the present cryo-FIB-SEM-EDS system further revealed the presence of K as a solute element, which is hardly identified by conventional techniques. Petrographic examination of the fluid inclusions indicated that they had been trapped during the exhumation stage of the UHP talc-garnet-chloritoid schist, possibly originating from the decompression breakdown of lawsonite. The data acquired from the present study challenges previous reports of the existence of simple chemical system of aqueous fluids in high-pressure and UHP metamorphic terrane in eastern Asia. This is imperative because misidentification of solute species introduces errors into salinity estimation, resulting in inaccuracy propagation in quantitative analytical processes such as LA-ICP-MS. A detailed fluid inclusion petrography would thus require accurate quantitative analysis involving FIB-based sample-preparation and SEM-EDS analysis.

著者

Takashi Miyazaki Kazutaka Yasukawa Erika Tanaka Bogdan Stefanov Vaglarov Kenta Yoshida

出版者

GEOCHEMICAL SOCIETY OF JAPAN

雑誌

GEOCHEMICAL JOURNAL (ISSN:00167002)

巻号頁・発行日

pp.GJ23011, (Released:2023-06-27)

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During the early Paleogene (59–50 Ma), several short-term global warming events, known as hyperthermal events, occurred. Negative carbon isotope (δ13C) excursions are a typical proxy for detecting hyperthermal events. During the recovery from hyperthermal events, δ13C values returned toward pre-event levels via scavenging lighter C isotopes from the ocean and sequestrating them within sediments. The biological pump plays a key role in this process. Barium (Ba) is a nutrient-type element primarily transported in the water column by barite formed in microenvironments associated with the decomposition of organic matter, and the Ba-stable isotope ratio is a proxy of biological productivity. In this study, the δ138/134Ba values of bulk sediment samples from Ocean Drilling Program Site 738C in the southern part of the Kerguelen–Heard Plateau were analyzed. Although the samples predominantly comprised calcareous chalk corresponding to the latest Paleocene to early Eocene (56–52 Ma), the Ba isotope ratios of the bulk samples reflected a mixture of carbonate and barite. Three negative δ138/134Ba shifts were detected, corresponding to the global super-warming event “Paleocene–Eocene Thermal Maximum” at 56 Ma and to two hyperthermal events, known as ETM2 and I1. The changes in δ138/134Ba and δ13C values during PETM were comparable to those reported from the South Atlantic Ocean. Although commonly recognized, the scale of δ138/134Ba changes was smaller in the modest hyperthermal events (ETM2 and I1). Ba stable isotope ratios are a highly effective and powerful tool to reveal the response of the surficial system of Earth during hyperthermal events.

著者

Adil KASYMBEKOV Akira TAKASU Md Fazle KABIR Shunsuke ENDO Apas B. BAKIROV Kadyrbek SAKIEV Rustam OROZBAEV Takao HIRAJIMA Kenta YOSHIDA

出版者

The Association for the Geological Collaboration in Japan

雑誌

地球科学 (ISSN:03666611)

巻号頁・発行日

vol.74, no.2, pp.47-64, 2020-05-25 (Released:2020-07-05)

参考文献数

43

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キルギス北部天山に分布する高圧-超高圧変成作用を受けたマクバル・コンプレックス(Makbal Complex)中のネルディ層(Neldy Formation)のざくろ石を含まない泥質片岩(KG1251)と含ざくろ石-クロリトイド泥質片岩(KG1244)の岩石記載と地質年代の測定を行った.KG1251 の主要造岩鉱物はフェンジャイト,緑泥石と石英であり,その他に少量の曹長石,チタン石,方解石,ルチル及び炭質物を含む.ピーク変成条件はT < 630 ℃,P = 0.9-1.7 GPa が見積もられた.片理を形成するフェンジャイトのK-Ar 年代は524 ± 13 Ma であり,これはこれまでに報告されているマクバル・コンプレックスのエクロジャイト及びざくろ石-クロリトイド-タルク片岩のピーク変成年代(ca. 500 Ma)と調和的である.KG1244 の主要構成鉱物は白色雲母(コアがフェンジャイト,リムが白雲母),緑泥石,石英であり,その他に少量のざくろ石,クロリトイド,曹長石,電気石,ジルコン,モナザイト,チタン石,ルチル,方解石及び炭質物を含む.ピーク変成条件はT = 485-545 ℃,P = 1.2-1.5 GPa の高圧型変成作用を示し,その後,T = ca. 500 ℃,P > 0.3 GPa の低圧型変成作用を受けた.この変成作用は花崗岩体の貫入にともなう接触変成作用と考えられた.本研究で得られた白色雲母のK-Ar 年代(474 ± 12 Ma)は,この地域に分布するオルドビス紀の花崗岩の年代(ca. 460 Ma)と調和的である.KG1251 及びKG1244 のネルディ層の泥質片岩の変成条件は,マクバル・コンプレックスの構造・層序学的に下部を占めるエクロジャイトやざくろ石-クロリトイド-タルク片岩に比べて有意に低圧であることが明らかになった.

著者

Satoru Haraguchi Kenta Ueki Kenta Yoshida Tatsu Kuwatani Mika Mohamed Shunsuke Horiuchi Hikaru Iwamori

出版者

The Geological Society of Japan

雑誌

地質学雑誌 (ISSN:00167630)

巻号頁・発行日

vol.124, no.12, pp.1049-1054, 2018-12-15 (Released:2019-03-15)

参考文献数

11

被引用文献数

5

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A geochemical database for the basement rocks of the Japanese islands has been constructed. These data were previously published in Japanese domestic journals and bulletins not readily accessible to the international community. The database includes 5818 samples from 224 articles, and provides major and trace element concentrations, isotopic ratios, geographical coordinates (latitude, longitude, and altitude) of sampling points, and geological and lithological information. These data are provided in a unified and consistent format as an Excel spreadsheet, which can be efficiently utilized for statistical analyses and data-driven approaches in geochemistry, geology, and petrology.

著者

Tatsu KUWATANI Kenji NAGATA Kenta YOSHIDA Masato OKADA Mitsuhiro TORIUMI

出版者

Japan Association of Mineralogical Sciences

雑誌

Journal of Mineralogical and Petrological Sciences (ISSN:13456296)

巻号頁・発行日

pp.170923, (Released:2018-04-19)

被引用文献数

5

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Geothermometry and geobarometry are used to study the equilibration of mineral inclusions and their zoned host minerals, which provide information on the P–T conditions of inclusions at the time of their entrapment. However, reconstructing detailed P–T paths remains difficult, owing to the sparsity of inclusions suitable for geothermometry and geobarometry. We developed a stochastic inversion method for reconstructing precise P–T paths from chemically zoned structures and inclusions using the Markov random field (MRF) model, a type of Bayesian stochastic method often used in image restoration. As baseline information for P–T path inversion, we introduce the concepts of pressure and temperature continuity during mineral growth into the MRF model. To evaluate the proposed model, it was applied to a P–T inversion problem using the garnet–biotite geothermometer and the garnet–Al2SiO5–plagioclase–quartz geobarometer for mineral compositions from published datasets of host garnets and mineral inclusions in pelitic schist. Our method successfully reconstructed the P–T path, even after removing a large part of the inclusion dataset. In addition, we found that by using a probability distribution of the most probable P–T path, rather than a single solution, an objective discussion of the validity of the thermodynamic analysis is possible.

著者

Kenta YOSHIDA Takao HIRAJIMA

出版者

Japan Association of Mineralogical Sciences

雑誌

Journal of Mineralogical and Petrological Sciences (ISSN:13456296)

巻号頁・発行日

pp.1202160190, (Released:2012-02-18)

被引用文献数

5 5

著者

Kenta YOSHIDA Yoshiteru SENGEN Shigeki TSUCHIYA Kouta MINAGAWA Tomoyuki KOBAYASHI Taketoshi MISHIMA Shinji OHSAWA Takao HIRAJIMA

出版者

Japan Association of Mineralogical Sciences

雑誌

Journal of Mineralogical and Petrological Sciences (ISSN:13456296)

巻号頁・発行日

vol.106, no.3, pp.164-168, 2011 (Released:2011-07-05)

参考文献数

26

被引用文献数

5 5

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A remarkably high Li/B ratio has been recognized from a crush-leached fluid extracted from a foliation-parallel quartz vein, IR27, intercalated with a pelitic schist in the northern proximal to the Western Iratsu body of the Sambagawa metamorphic belt, SW Japan. Thin section observation shows that most quartz grains in the vein are polygonal and rarely show the undulatory extinction. These facts suggest that the quartz grains in the vein could be recrystallized under relatively high-T condition with the stress free environment, and that these fluid inclusions could be trapped during the peak metamorphic stage. Most fluid inclusions in the investigated sample are composed of liquid and vapor. Raman spectroscopy revealed that the liquid phase is aqueous fluid and the vapor is mainly a mixture of CH4 and N2. Their ice melting temperatures determined by microthermometry, ranging from -3.5 to -7.1 °C, show a striking contrast against the data of the fluid inclusions in later stage veins, ranging from -0.6 to -1.7 °C. However, the homogenization temperatures of IR27 are much lower than the peak metamorphic temperature of the host pelitic schist. The partition coefficients between the host rock and released fluid (Drock/fluid) calculated from P-T pseudosection show that DBrock/fluid tends to be higher than DLirock/fluid in a pelitic system, because of generally high modes of white mica in pelitic schists. The calculation suggests that the crush-leached fluid obtained from the quartz vein intercalated with the pelitic schist has higher Li/B ratio than fluids of those intercalated with the metabasite.