Updated on 2023/06/06

写真a

 
TAGUCHI, Tomoki
 
Scopus Paper Info  
Paper Count: 14  Citation Count: 119  h-index: 8

Click to view the Scopus page. The data was downloaded from Scopus API in June 05, 2023, via http://api.elsevier.com and http://www.scopus.com .

Affiliation
Faculty of Education and Integrated Arts and Sciences, School of Education
Job title
Associate Professor
Degree
2016/03 名古屋大学 博士(理学)

Research Experience

  • 2023.04
    -
    Now

    Waseda University   Faculty of Education and Integrated Arts and Sciences

  • 2023.04
    -
    Now

    Waseda University   Graduate School of Creative Science and Engineering

  • 2020.04
    -
    2023.03

    Waseda University   Faculty of Education and Integrated Arts and Sciences

  • 2017.04
    -
    2020.03

    Kyoto University   Graduate School of Science

  • 2016.04
    -
    2017.03

    Nagoya University   Institute for Space and Earth Environmental Research

  • 2015.04
    -
    2016.03

    Nagoya University   Graduate School of Environmental Studies

▼display all

Education Background

  • 2013.04
    -
    2016.03

    Nagoya University   Graduate School of Environmental Studies   Department of Earth and Environmental Sciences  

  • 2011.04
    -
    2013.03

    Nagoya University   Graduate School of Environmental Studies   Department of Earth and Environmental Sciences  

  • 2007.04
    -
    2011.03

    Shizuoka University   Faculty of Science   Department of Geosciences  

Professional Memberships

  •  
     
     

    THE GEOLOGICAL SOCIETY OF JAPAN

  •  
     
     

    Japan Association of Mineralogical Sciences

  •  
     
     

    JAPAN GEOSCIENCE UNION

  •  
     
     

    American Geophysical Union

Research Areas

  • Solid earth sciences

Research Interests

  • Mineralogy

  • Raman spectroscopy

  • Petrology

  • Metamorphic rock

Awards

  • JMPS 第1回学生論文賞

    2016.09   日本鉱物科学会  

    Winner: 田口 知樹

  • 第16回論文賞

    2015.09   日本鉱物科学会  

    Winner: 田口 知樹, 榎並 正樹

  • 2015年年会研究発表優秀賞

    2015.09   日本鉱物科学会  

    Winner: 田口 知樹

 

Papers

  • Formation process of Al-rich calcium amphibole in quartz-bearing eclogites from The Sulu Belt, China

    Masaki Enami, Tomoki Taguchi, Yui Kouketsu, Katsuyoshi Michibayashi, Tadao Nishiyama

    American Mineralogist   107 ( 8 ) 1582 - 1597  2022.08  [Refereed]

     View Summary

    Abstract

    Aluminum-rich and Si-poor calcium amphibole [~3.9 Al atoms per formula unit (apfu) and ~5.5 Si apfu for 23 O] occur in the quartz-bearing eclogites from the Donghai area, Sulu ultrahigh-pressure metamorphic belt, eastern China. Most of the aluminous amphibole phases are retrograde products from the exhumation and hydration stage and are texturally divided into a mantle phase around a porphyroblastic garnet and a crack-filling (vein) phase of a garnet. Less aluminous amphibole occurs as symplectite phase with plagioclase after omphacite. The formation process of the aluminous amphibole in the quartz-bearing samples is discussed on the basis of the analytical data by EPMA, FIB-TEM, and EBSD.

    The mantle amphibole occurs between garnet and symplectite or quartz. A set of plagioclase and aegirinediopside/argirine-hedenbergite thin monomineralic bands forms at the boundary between the mantle amphibole and matrix quartz. However, these monomineralic bands do not occur at the mantle amphibole-symplectite boundary. These textural differences indicate that the recrystallization of the aluminous amphibole around garnet was controlled by significant local reactions, and the size of equilibrate domains was probably several tens of micrometers or less.

    The mantle amphibole is composed of inner (garnet-side) and outer (matrix-side) zones. The inner zone is compositionally homogeneous, and its atomic Al/Si value is ~0.63–0.66 and similar to that of garnet. Atomic Ca/Si value in the inner zone is also almost uniform and is generally identical to that of garnet. The outer zone exhibits a monotonic decrease in the Al/Si and Ca/Si values outward, and its composition at the outermost margin is similar to that of the symplectitic amphibole. The crack-filling amphibole has a composition similar to the inner zone of the mantle amphibole. The CPO pattern of the crack-filling amphibole is different from that of the adjacent mantle amphibole, showing that the crack-filling amphibole is cut by the mantle amphibole. The textural relationship between the mantle and crack-filling amphibole phases and their compositional characteristics imply that: (1) the mantle type is a slightly later stage product than the crack-filling type, and (2) the boundary between the inner and outer zones of the mantle aluminous amphibole probably corresponds to the initial surface of the porphyroblastic garnet. The inner zone is considered to have grown inward by simple substitution of garnet, using the tetrahedral and octahedral cations of the garnet as the basic framework. On the other hand, most of the outer zone of the mantle-type amphibole grew outward in the matrix from the initial surface of the garnet porphyroblast. The mantle amphibole shows a CPO similar to that of amphibole in the adjacent symplectite domain, suggesting that these two types of amphibole formed almost simultaneously, sharing crystallographic orientation with each other.

    The formation of crack-filling aluminous amphibole was probably promoted by the hydraulic microfrac-turing process at an early stage of exhumation and hydration. The mantle and symplectitic amphibole phases formation was promoted by the subsequent infiltration of metamorphic fluid. The aluminous amphibole in the SiO2 phase-bearing eclogites probably recrystallized with the formation of a localized SiO2-undersaturated reaction domain because of rapid exhumation and subsequent rapid cooling of the Sulu UHP metamorphic belt.

    DOI

    Scopus

    1
    Citation
    (Scopus)
  • Raman Geobarometry of Quartz Inclusions in Kyanite: Application to Quartz Eclogite from the Gongen Area of the Sanbagawa Belt, Southwest Japan

    Yuki Tomioka, Yui Kouketsu, Tomoki Taguchi

    The Canadian Mineralogist   60 ( 1 ) 121 - 132  2022.01  [Refereed]

    Authorship:Last author

     View Summary

    ABSTRACT

    Residual pressure values of quartz inclusions in host kyanite were estimated using Raman spectroscopy and show that the quartz-inclusions-in-kyanite system can be used as a geobarometer for estimating peak metamorphic conditions. Samples of quartz eclogite, a pelitic high-pressure metamorphic rock composed mainly of garnet, omphacite, and quartz, with subordinate kyanite, were obtained for analysis from the Gongen area in the Sanbagawa metamorphic belt, southwest Japan. Residual pressure in the 236 analyzed quartz inclusions within kyanite grains varies from 0.12 to 0.76 GPa. Values are independent of inclusion size and inclusion aspect ratio, and the distribution of residual pressure within the inclusions is homogeneous, except at inclusion-host interfaces. Numerical calculations based on elastic modeling with the equations of state of quartz and kyanite were applied using the highest residual pressure value of 0.76 GPa, with the calculated isopleth being consistent with previous results obtained by conventional thermodynamic geothermobarometry. We conclude that the quartz-inclusions-in-kyanite system can be used as a reliable new Raman geobarometer.

    DOI

    Scopus

    1
    Citation
    (Scopus)
  • Thermal structure in subducted units from continental Moho depths in a palaeo subduction zone, the Asemigawa region of the Sanbagawa metamorphic belt, SW Japan

    Yui Kouketsu, Kazushi Sadamoto, Hayato Umeda, Hirokazu Kawahara, Takayoshi Nagaya, Tomoki Taguchi, Hiroshi Mori, Simon Wallis, Masaki Enami

    Journal of Metamorphic Geology   39 ( 6 ) 727 - 749  2021.08  [Refereed]

    DOI

    Scopus

    7
    Citation
    (Scopus)
  • Hidden intact coesite in deeply subducted rocks

    Tomoki Taguchi, Yui Kouketsu, Yohei Igami, Tomoyuki Kobayashi, Akira Miyake

    Earth and Planetary Science Letters   558   116763 - 116763  2021.03  [Refereed]

    Authorship:Lead author, Corresponding author

     View Summary

    The stabilization of coesite is a diagnostic indicator of ultrahigh-pressure metamorphism and in many cases it implies that a rock has been subducted to a minimum depth of 80 km. Coesite typically occurs as rare relicts in rigid host minerals, but most commonly transforms into alpha-quartz pseudomorphs during exhumation. The abundance of coesite-bearing rocks in orogens worldwide is a contentious issue in the petrological community, despite evidence from numerical modeling that suggests that coesite formation should be a common geological process during ultrahigh-pressure metamorphism. This knowledge gap must be addressed to improve the understanding of the geological aspects of subductionzone geodynamics. Here we report that minuscule coesites (<20 mu m) occur as abundant inclusions in garnet-rich layers from the Italian Western Alps. The discovery of such intact inclusions may fill the gaps in the predicted and observed abundances of coesite worldwide. Through integrated approaches with resolutions down to the nano-scale, we show that these garnet-hosted inclusions are composed entirely of coesite. Our results suggest that common coesite-derived quartz pseudomorphs are less typical structures in ultrahigh-pressure metamorphic rocks and the minuscule coesite in many rocks may be overlooked because of its size. These findings open up new research directions for constraining the extent of deeply subducted rocks and their rheology. (C) 2021 Elsevier B.V. All rights reserved.

    DOI

    Scopus

    4
    Citation
    (Scopus)
  • Early Carboniferous HP metamorphism in the Hida Gaien Belt, Japan: Implications for the Palaeozoic tectonic history of proto‐Japan

    Takumi Yoshida, Tomoki Taguchi, Hayato Ueda, Kenji Horie, M. Satish‐Kumar

    Journal of Metamorphic Geology   39 ( 1 ) 77 - 100  2021.01  [Refereed]

    DOI

    Scopus

    10
    Citation
    (Scopus)
  • Drastic effect of shearing on graphite microtexture: attention and application to Earth science

    Yui Kouketsu, Akira Miyake, Yohei Igami, Tomoki Taguchi, Hiroyuki Kagi, Masaki Enami

    Progress in Earth and Planetary Science   6 ( 1 )  2019.12  [Refereed]

     View Summary

    © 2019, The Author(s). The microtexture of graphite exposed on the polished surface was studied using confocal laser scanning microscopy, laser Raman spectroscopy, and focused ion beam–transmission electron microscopy (FIB–TEM) to elucidate the effect on surface condition and crystallinity of graphite by polishing process. The polished surface of the graphite was divided into a flat part with no irregularities and a grooved band with a width of < 1 μm and a depth of < 100 nm. Raman analyses revealed that the original structure of the graphite covered by the host mineral was a well-ordered graphite, whereas the polished graphite at the surface had a reduced crystallinity, particularly in the flat part of the sample. Based on scanning TEM observations of an ultra-thin FIB section, fractures that developed during sample preparation were concentrated in the region extending from the surface to a depth of 1 μm. Furthermore, graphite sheets were peeled away by shearing, with scraped graphite sheets filling in the gap. Our results demonstrate that the original microtexture of graphite was easily deformed by shearing during polishing, and careful attention should be paid to sample preparation. In addition, we also need to pay more attention to the effects of natural shearing such as faulting on the graphite or sheet-like minerals. [Figure not available: see fulltext.].

    DOI

    Scopus

    13
    Citation
    (Scopus)
  • A new occurrence of retrogressed eclogite from the Sanbagawa belt of southwest Japan and its significance

    Tomoki Taguchi, Shunsuke Endo, Yohei Igami, Akira Miyake

    ISLAND ARC   28 ( 5 ) e12317  2019.09  [Refereed]

     View Summary

    The present paper reports, for the first time, the occurrence of an omphacite-bearing mafic schist from the Asemi-gawa region of the Sanbagawa belt (southwest Japan). The mafic schist occurs as thin layers within pelitic schist of the albite-biotite zone. Omphacite in the mafic schist only occurs as inclusions in garnet, and albite is the major Na phase in the matrix, suggesting that the mafic schist represents highly retrogressed eclogite. Garnet grains in the sample show prograde-type compositional zoning with no textural or compositional break, and contain mineral inclusions of omphacite, quartz, glaucophane, barroisite/hornblende, epidote and titanite. In addition to the petrographic observations, Raman spectroscopy and focused ion beam system-transmission electron microscope analyses were used for identification of omphacite in the sample. The omphacite in the sample shows a strong Raman peak at 678 cm(-1), and concomitant Raman peaks are all consistent with those of the reference omphacite Raman spectrum. The selected area electron diffraction pattern of the omphacite is compatible with the common P2/n omphacite structure. Quartz inclusions in the mafic schist preserve high residual pressure values of Delta omega(1) > 8.5 cm(-1), corresponding to the eclogite facies conditions. The combination of Raman geothermobarometries and garnet-clinopyroxene geothermometry gives peak pressure-temperature (P-T) conditions of 1.7-2.0 GPa and 440-540 degrees C for the mafic schist. The peak P-T values are comparable to those of the schistose eclogitic rocks in other Sanbagawa eclogite units of Shikoku. These findings along with previous age constraints suggest that most of the Sanbagawa schistose eclogites and associated metasedimentary rocks share similar simple P-T histories along the Late Cretaceous subduction zone.

    DOI

    Scopus

    1
    Citation
    (Scopus)
  • Factors affecting preservation of coesite in ultrahigh-pressure metamorphic rocks: Insights from TEM observations of dislocations within kyanite

    Tomoki Taguchi, Yohei Igami, Akira Miyake, Masaki Enami

    Journal of Metamorphic Geology   37 ( 3 ) 401 - 414  2019.04  [Refereed]

     View Summary

    © 2019 John Wiley & Sons Ltd To understand the preservation of coesite inclusions in ultrahigh-pressure (UHP) metamorphic rocks, an integrated petrological, Raman spectroscopic and focussed ion beam (FIB) system–transmission electron microscope (TEM) study was performed on a UHP kyanite eclogite from the Sulu belt in eastern China. Coesite grains have been observed only as rare inclusions in kyanite from the outer segment of garnet and in the matrix. Raman mapping analysis shows that a coesite inclusion in kyanite from the garnet rim records an anisotropic residual stress and retains a maximum residual pressure of ~0.35 GPa. TEM observations show quartz is absent from the coesite inclusion–host kyanite grain boundaries. Numerous dislocations and sub-grain boundaries are present in the kyanite, but dislocations are not confirmed in the coesite. In particular, dislocations concentrate in the kyanite adjacent to the boundary with the coesite inclusion, and they form a dislocation concentration zone with a dislocation density of ~10 9  cm −2 . A high-resolution TEM image and a fast Fourier transform-filtered image reveal that a tiny dislocation in the dislocation concentration zone is composed of multiple edge dislocations. The estimated dislocation density in most of the kyanite away from the coesite inclusion–host kyanite grain boundaries is ~10 8  cm −2 , being lower than that in kyanite adjacent to the coesite. In the case of a coesite inclusion in a matrix kyanite, using Raman and TEM analyses, we could not identify any quartz at the grain boundaries. Dislocations are not observed in the coesite, but numerous dislocations and stacking faults are developed in the kyanite. The estimated overall dislocation density in the coesite-bearing matrix kyanite is ~10 8  cm −2 , but a high dislocation density region of ~10 9  cm −2 is also present near the coesite inclusion–host kyanite grain boundaries. Inclusion and matrix kyanite grains with no coesite have dislocation densities of ≤10 8  cm −2 . Dislocation density is generally reduced during an annealing process, but our results show that not all dislocations in the kyanite have recovered uniformly during exhumation of the UHP rocks. Hence, one of the key factors acting as a buffer to inhibit the coesite to quartz transformation is the mechanical interaction between the host and the inclusion that lead to the formation of dislocations in the kyanite. The kyanite acts as an excellent pressure container that can preserve coesite during the decompression of rocks from UHP conditions. The search for and study of inclusions in kyanite may be a more suitable approach for tracing the spatial distribution of UHP metamorphic rocks.

    DOI

    Scopus

    8
    Citation
    (Scopus)
  • Metamorphic record of the Asemi‐gawa eclogite unit in the Sanbagawa belt, southwest Japan: Constraints from inclusions study in garnet porphyroblasts

    Tomoki Taguchi, Masaki Enami, Yui Kouketsu

    Journal of Metamorphic Geology   37 ( 2 ) 181 - 201  2019.02  [Refereed]

    DOI

    Scopus

    17
    Citation
    (Scopus)
  • Chemical factors controlling occurrence of staurolite in the Ryoke metamorphic rocks of the Hongu-san area, Aichi Prefecture

    Shisaka Shunya, Naito Takahito, Sugiura Yasuhiko, Inaishi Takumi, Taguchi Tomoki, Miyake Akira

    The Journal of the Geological Society of Japan   125 ( 4 ) 263 - 278  2019  [Refereed]

     View Summary

    <p>Eleven localities of staurolite-bearing metapelites and pelitic bands in metachert, are reported from the Ryoke metamorphic belt in the Hongu-san area (Aichi Prefecture, Japan). Staurolite occurs as inclusions within andalusite porphyroblasts and within mica-quartz aggregates in metapelites. On the other hand, staurolite in pelitic bands in metachert, occurs not only as inclusions within mica-quartz aggregates but also as porphyroblast. Petrographic observations indicate that the mica-quartz aggregates were formed by replacing staurolite porphyroblasts during prograde stage of the Ryoke regional metamorphism. Based on the widespread spatial distribution of the mica-quartz aggregates, it is suggested that staurolite was widely produced in the area. During subsequent stages of prograde and peak metamorphism, staurolite became unstable in some rocks while remaining stable in others. Thermodynamic calculations reveal that the Ti content of biotite and the Zn content of staurolite affect the stability of staurolite, thus explaining its heterogeneous preservation in the study area.</p>

    DOI CiNii

  • Significance of an amorphous SiO<inf>2</inf> phase in a pseudomorph after coesite enclosed in garnet from ultrahigh-pressure eclogite, Su–Lu Belt, eastern China

    Tomoki Taguchi, Akira Miyake, Masaki Enami, Yohei Igami

    Journal of Metamorphic Geology   36 ( 7 ) 843 - 854  2018.09  [Refereed]

     View Summary

    © 2018 John Wiley & Sons Ltd Here, we report the first discovery of an amorphous SiO2 phase (APSI phase) in a pseudomorph after coesite included in garnet from an ultrahigh-pressure (UHP) eclogite from the Su–Lu metamorphic belt, eastern China. Using transmission electron microscopy, Raman spectroscopy and selected area electron diffraction, we show that the internal structure of the pseudomorph consists of an APSI phase with nano/submicrocrystalline particles of quartz and a polycrystalline K-bearing fibrous sheet-silicate phase (KFSS phase). The APSI phase-bearing aggregates included in the garnet might have formed by reactions involving a supercritical fluid during exhumation by the following processes: (1) the development of radial cracks within the host garnet by the phase transition of coesite to quartz; (2) the decomposition of a part of the pseudomorph following infiltration of supercritical fluid; (3) the precipitation of the KFSS phase from the fluid phase during subsequent exhumation and cooling, which was likely promoted by a change in the metamorphic fluid from supercritical and/or subcritical to aqueous fluid; and (4) the rapid precipitation of the APSI phase under a metastable (non-equilibrium) state, such as quenching, during a later stage of the exhumation. Whether the APSI phase generally formed during exhumation and survived widely throughout the Su-Lu terrane is unknown. However, the presence of the APSI phase in a UHP eclogite provides new insight into the geodynamic phenomena occurring at continental collision zones.

    DOI

    Scopus

    3
    Citation
    (Scopus)
  • Finding of staurolite-bearing pelitic schists in the Ryoke metamorphic belt of the Dando-san area, Aichi Prefecture and its significance

    Miyake Akira, Igarashi Yukari, Inaishi Takumi, Taguchi Tomoki

    Jour. Geol. Soc. Japan   123 ( 2 ) 59 - 72  2017  [Refereed]

     View Summary

    &lt;p&gt;Schistose staurolite-bearing pelites occur in the Ryoke Metamorphic Belt, Dando-san area, Aichi Prefecture, Japan. These rocks contain andalusite porphyroblasts and coarse-grained elongate mica-quartz aggregates composed of muscovite, biotite, and quartz in a matrix of muscovite, biotite, quartz, and fibrolite. Staurolite occurs as inclusions in andalusite porphyroblasts and in the minerals of the micaquartz aggregates. Detailed microscopy indicates that a staurolite-consuming and andalusite-producing reaction occurred before the deformation causing the schistosity, such that staurolite grains apart from andalusite porphyroblasts have been replaced by mica-quartz aggregates, and those adjacent to the porphyroblasts have been replaced by andalusite. It is possible that the prograde &lt;i&gt;P&lt;/i&gt;-&lt;i&gt;T&lt;/i&gt; paths of the staurolite-bearing pelites of the Dando-san and Hazu-Hongu-san areas lie on the high-pressure side of those of staurolite-free pelitic rocks with similar metamorphic grades in other areas of the Ryoke Belt.&lt;/p&gt;

    DOI CiNii

  • Prograde evolution of Sulu UHP metamorphic rock in Yangzhuang, Junan region, deduced by combined Raman and petrological studies

    T. Taguchi, M. Enami, Y. Kouketsu

    JOURNAL OF METAMORPHIC GEOLOGY   34 ( 7 ) 683 - 696  2016.09  [Refereed]

     View Summary

    The prograde metamorphic history of the Sulu ultrahigh-pressure metamorphic terrane has been revealed using Raman-based barometry of the SiO2 phases and other mineral inclusions in garnet porphyroblasts of a coesite eclogite from Yangzhuang, Junan region, eastern China. Garnet porphyroblasts have inner and outer segments with the boundary being marked by discontinuous changes in the grossular content. In the inner segment, the SiO2 phase inclusions are -quartz with no coesite or relict features such as radial cracks. The residual pressures retained by the quartz inclusions systematically increase from the crystal centre to the margin of the inner segment. The metamorphic conditions estimated by calculation from the residual pressure and conventional thermodynamic calculation range from 500 to 630 degrees C and 1.3 to 2.3GPa for the stage of the inner segment. Coesite and its pseudomorph occur as inclusions in the outer segment of the garnet and matrix omphacite. This occurrence of coesite is consistent with the pressure and temperature conditions of 660-725 degrees C and 3.1GPa estimated by conventional geothermobarometry. Our results suggest that the quartz inclusions in the inner segment were trapped by garnet under -quartz-stable conditions and survived phase transition to coesite at the peak metamorphic stage. The SiO2 phases and other inclusions in the garnet have retained evidence of the pre-eclogite prograde stage even during exhumation stage. The combined Raman spectroscopic and petrological approaches used here offers a powerful means for obtaining more robust constraints prograde stages involving garnet growth where different SiO2 phases are present as inclusions.

    DOI

    Scopus

    9
    Citation
    (Scopus)
  • Large thermal aureole around the Inagawa Granodiorite in the southeastern area of Asuke, Aichi Prefecture

    Miyake Akira, Hirukawa Takanobu, Sato Maki, Taguchi Tomoki, Suzuki Kazuhiro, Nakai Yutaka

    Jour. Geol. Soc. Japan   122 ( 5 ) 173 - 191  2016  [Refereed]

     View Summary

    In Aichi Prefecture of Central Japan, metamorphic rocks of the Ryoke Belt are intruded by the Inagawa Granodiorite southeast of the town of Asuke. The pluton extends in a NE-SW direction for ca. 120 km with a width of ca. 25 km at its southwestern end and consists of four distinct intrusive units. A new CHIME monazite age of 83.3±1.3 Ma for the third unit is within error of a previously reported age of 83-82 Ma for the forth unit, thereby supporting the proposal that the whole of the granodiorite intrusion solidified over a shorttime span. Geological and petrological evidence, including metamorphic zones, the occurrence of prismatic sillimanite after andalusite, and the spatial distribution of migmatitic rocks, shows that the metamorphic grade increases gradually towards the northwest as the contact with the granodiorite is approached. The width of the thermal aureole recognized during mapping reaches 8 km, whereas its true width is estimated to be ca. 5 km after correcting for the dip of the contact between the pluton and country rocks. The wide thermal aureole around the Inagawa Granodiorite is ascribed to the large heat capacity of the intrusion and the elevated geothermal gradient that existed in the region at the time, owing to the active magmatic processes during the successive emplacement of the Younger Ryoke granitoids.

    DOI CiNii

  • Crust–mantle interactions in subduction zones: Constraints from inclusions study in garnet porphyroblasts

    Tomoki Taguchi

        7 - 13  2015

    Authorship:Lead author, Corresponding author

  • Coexistence of jadeite and quartz in garnet of the Sanbagawa metapelite from the Asemi-gawa region, central Shikoku, Japan

    Tomoki Taguchi, Masaki Enami

    JOURNAL OF MINERALOGICAL AND PETROLOGICAL SCIENCES   109 ( 4 ) 169 - 176  2014.08  [Refereed]

     View Summary

    Coexistence of jadeite (Jd(92)) and quartz was newly found in an inner segment of a composite-zoned garnet from a metapelite in the southern albite-biotite zone of the Asemi-gawa region, Sanbagawa belt in central Shikoku, Japan. The assemblage of jadeite + quartz in garnet gives a minimum metamorphic pressure of 1.4-1.9 GPa at 500-700 degrees C, which was significantly higher than that previously proposed for epidote-amphibolite facies conditions in the albite-biotite zone. Garnet includes quartz retaining high residual pressure (Delta omega(1) values up to 11.7 cm(-1)), which is comparable to the residual pressure reported in eclogite and metapelite within the eclogite unit in central Shikoku. These results imply that (1) the inner segment of the composite-zoned garnet records prograde recrystallization under high-pressure blueschist to eclogite facies conditions and (2) at least a part of the southern albite-biotite zone of the Asemi-gawa region recrystallized under higher pressure conditions prior to the regional metamorphism from the greenschist to epidote-amphibolite facies that formed the regional thermal structure of the Sanbagawa belt of central Shikoku.

    DOI

    Scopus

    17
    Citation
    (Scopus)
  • Compositional zoning and inclusions of garnet in Sanbagawa metapelites from the Asemi-gawa route, central Shikoku, Japan

    Tomoki Taguchi, Masaki Enami

    JOURNAL OF MINERALOGICAL AND PETROLOGICAL SCIENCES   109 ( 1 ) 1 - 12  2014.02  [Refereed]

     View Summary

    Compositional and textural characteristics of the zonal structure and inclusions of garnet in metapelites from areas of high-grade greenschist facies (garnet zone) to areas of epidote-amphibolite facies (albite-biotite and oligoclase biotite zones) located along the Asemi-gawa route were examined using EPMA and Raman spectroscopy to investigate evolution of the P-T history of Sanbagawa metamorphism. Garnet grains exhibit two types of compositional zoning patterns: bell-shaped and composite types with spessartine variation. Bell-shape zoning is characterized by a monotonous decrease in the spessartine component from the crystal core towards the margin. Almandine and pyrope components exhibit the opposite trend. The grossular content reaches a maximum at an intermediate position between the core and the rim, and then decreases towards the outermost rim. The composite-zoned garnet is divided into core and mantle parts and it exhibits discontinuous compositional variations according to the associated boundary, evidencing resorption of the core and overgrowth of the mantle during crystallization; implying a two-stage growth of garnet during the Sanbagawa metamorphism. Composite-zoned garnet is characteristically observed in metapelites from a part of the albite-biotite zone, and quartz grains included in its core retain a higher residual pressure than those in garnet from other mineral zones. Isolated paragonite crystal occurs particularly as an inclusion in the core part of this composite-zoned garnet. These data suggest that part of the Sanbagawa metamorphic rocks in the Asemi-gawa region recrystallized under higher-pressure conditions up to the eclogite facies, prior to regional metamorphism from the greenschist, to the epidote-amphibolite facies that formed the regional thermal structure of the Sanbagawa belt of central Shikoku.

    DOI

    Scopus

    17
    Citation
    (Scopus)
  • PETROGENESIS OF Cr-RICH CALC-SILICATE ROCKS FROM THE BANDIHALLI SUPRACRUSTAL BELT, ARCHEAN DHARWAR CRATON, INDIA

    Tomoki Taguchi, Madhusoodhan Satish-Kumar, Tomokazu Hokada, Mudlappa Jayananda

    CANADIAN MINERALOGIST   50 ( 3 ) 705 - 718  2012.06  [Refereed]

     View Summary

    Chromium-rich calc-silicate rocks in the Archaean Bandihalli supracrustal belt in the Dharwar Craton, India, show a characteristic mineral assemblage that includes euhedral and anhedral (resorbed) green garnet associated with chromite, in addition to diopside, quartz, clinozoisite and calcite. Two distinct types of green garnets and a brown variety were identified in the calc-silicate rocks. These garnets show complex chemical compositional variations that range between the endmembers of uvarovite, grossular, and spessartine. Chromite grains in the matrix are euhedral or subhedral, whereas inclusions in garnet are rounded or amoeboid in shape. The two textural varieties of chromite from Bandihalli are separated by a compositional gap. Furthermore, chromites from the study area have high Cr# (0.80-0.97) and low Mg# (0.01-0.04), which is similar to the chromite in serpentinites and are in contrast with chromite compositions reported from igneous rocks. Therefore, the chromite in the calc-silicate rocks may have been derived from serpentinized ultramafic rocks. Textural and compositional data presented here provide evidence for chemical changes of the primary chromite with increasing metamorphic grade, presumably associated with primary hydrothermal alteration that resulted in serpentinization and carbonation of the ultramafic protolith. Therefore, Cr-rich calc-silicate rocks can be considered as products of metamorphosed carbonated and serpentinized mafic or ultramafic igneous rocks.

    DOI

    Scopus

    11
    Citation
    (Scopus)

▼display all

Research Projects

  • Experimental study of Raman geobarometry using hydrothermal diamond anvil cell

    Japan Society for the Promotion of Science  Grants-in-Aid for Scientific Research Grant-in-Aid for Scientific Research (B)

    Project Year :

    2022.04
    -
    2026.03
     

  • 高圧ー超高圧変成岩に適用可能な新しいラマン地質圧力計の開発

    日本学術振興会  科学研究費助成事業 基盤研究(C)

    Project Year :

    2019.04
    -
    2022.03
     

    田口 知樹, 纐纈 佑衣

  • 多相固体包有物のナノ組織解析:超高圧変成岩上昇期の流体挙動の解明に向けて

    日本学術振興会  科学研究費助成事業 特別研究員奨励費

    Project Year :

    2017.04
    -
    2020.03
     

    田口 知樹

  • 石英ラマン圧力計の超高圧変成岩への適用:変成履歴を残留圧力から読み解く

    日本学術振興会  科学研究費助成事業 特別研究員奨励費

    Project Year :

    2015.04
    -
    2017.03
     

    田口 知樹

  • ザクロ石の鉱物包有物から探る沈み込み帯の地殻・マントル 相互作用

    深田地質研究所  深田研究助成

    Project Year :

    2014.04
    -
    2015.03
     

    田口 知樹

 

Syllabus

▼display all

 

Sub-affiliation

  • Faculty of Science and Engineering   Graduate School of Creative Science and Engineering

Internal Special Research Projects

  • ラマン分光法による鉱物包有物分析の条件最適化に関する研究

    2022  

     View Summary

    ラマン分光装置は初学者にとっても取り扱いが比較的容易であるが、信頼できるデータの取得には分析条件の最適化や標準試料の精査が求められる。本課題では、新規導入した顕微ラマン分光装置について、鉱物包有物分析に最適化した条件を見出すことを目的に研究を進めた。特に、ラマン地質温度圧力計で頻用される石英および炭質物に着目し、レーザー出力の多段階調整や鉱物ラマンスペクトルのピークフィッティング解析を行った。その結果、各鉱物の分析条件(レーザー出力、露光時間、対物レンズなど)を最適化することに成功し、温度圧力既知の岩石試料を用いた分析においても、先行研究の推定値と整合的なデータが得られた。

  • 岩石レオロジー研究の新機軸:結晶欠陥の迅速解析手法の確立

    2022  

     View Summary

    岩石レオロジーを定式化する上で、結晶欠陥(転位)の運動様式や密度は必要不可欠な情報となる。しかし、その観察分析法は研究者の知識経験に大きく依存し、転位分布と鉱物組織の関係性を調べることは容易でない。本研究課題ではラマン分光法に基づき、結晶欠陥の種類や分布を特定することが可能かを検証した。本年度は基礎研究として、微小硬度計を用いて石英に人工転位を再現可能か試行した。分析機器メーカーにおけるデモ分析で微小圧痕を作成し、その周囲に残留応力を保持しているかを検証した。ラマン分析条件の最適化など今後必要であるが、次年度以降も継続して結晶欠陥解析法の構築を進めていく予定である。

  • 高圧ー超高圧変成岩に適用可能な新しいラマン地質圧力計の開発

    2022  

     View Summary

    本研究課題では、ラマン分光分析を軸に、高圧―超高圧変成岩の形成圧力条件を推定できる新規ラマン地質圧力計の開発を目指した。藍晶石―石英系における石英残留圧力の数値計算を実施し、藍晶石に着目した新たなラマン地質圧力計の構築に成功した。本ラマン圧力計を西南日本三波川帯の石英エクロジャイトに適用した結果、先行研究で報告されている熱力学的推定値と矛盾のないデータが得られた。また、超高圧変成作用を経験したスロベニア産片麻岩にも適用したところ、負の残留圧力を保持する石英を確認した。これは片麻岩の岩石上昇期の変成史を解読する上で有用なデータであり、次年度以降も検証を続ける予定である。

  • 副成分鉱物の残留圧力から読み解く変成履歴

    2021  

     View Summary

    変成鉱物内に取り込まれた包有物の残留圧力を用いて、天然変成岩の変成履歴解析が可能か検証した。本研究課題では、西南日本三波川帯および中国蘇魯帯のエクロジャイトの藍晶石およびルチルに着目した。藍晶石を対象としたラマン分析と数値計算モデルにより算出された変成圧力値は、先行研究の推定値と遜色ないものであった。一方、ルチルについてはラマン分析条件の設定など再考すべき点があるものの、ピークシフト量から残留圧力推定は可能であると示唆される。今後、ラマン分光分析装置による鉱物包有物測定の条件最適化に関する研究も推進する予定である。

  • ラマン分光学に基づく新たな地質温度圧力計の開発

    2020  

     View Summary

    本課題では、藍晶石内に存在するシリカ包有物の「残留圧力」に焦点を当て、ラマン分光学に基づく新たな地質圧力計の開発を目指した。天然の高圧変成岩を対象に、石英包有物のラマン分析を実施し、その残留圧力値から変成条件の制約を試みた。最新の数値計算モデルを用いて残留圧力値から推定した変成圧力条件は、先行研究の熱力学的解析によって見積もられたピーク変成条件と調和的であった。これまでに得られた成果をまとめて、当該分野の査読付き国際誌に投稿済みの状態にあり、全体としてはおおむね順調に研究が進展したと言える。