Chloritoid-bearing basic schists from the Sanbagawa metamorphic belt, central Shikoku: their petrologic significance and tectonic implications

DOI BIBCODE 5 Citations 51 References
  • Ko Zaw Win
    Department of Earth and Planetary Sciences, Nagoya University, Chikusa-ku Present address: No. 30, Block-Ma 37, Yemon (South), Maha Aung May Township, Mandalay, Myanmar
  • ENAMI Masaki
    Department of Earth and Planetary Sciences, Nagoya University, Chikusa-ku
  • AOYA Mutsuki
    Department of Earth and Planetary Sciences, Nagoya University, Chikusa-ku Present address: Institute of Geology and Geoinformation, National Institute of Advanced Industrial Science and Technology (AIST), Central 7, Higashi 1-1-1, Tsukuba 305-8567, Japan

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  • Chloritoid-bearing basic schists from Sanbagawa metamorphic belt, central Shikoku, Japan: Their petrologic significance and evidence for presence of major tectonic boundary

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Abstract

Chloritoid- and taramite-bearing basic schists occur on the streambed at Ikadadu in the garnet zone of the Sanbagawa metamorphic belt, central Shikoku. Their major constituent phases are chloritoid, taramite, chlorite, paragonite, phengite, epidote, ilmenite, titanite, albite and quartz. Chloritoid occurs only as inclusions in garnet. The appearance of chloritoid in the basic schists is strongly dependent on their restricted FeO-rich and high Al2O3/(CaO + Na2O + K2O) bulk-rock compositions. The metamorphic pressure (P) and temperature (T) conditions, 0.9 GPa and 505-515°C, are estimated by using equilibrium relationships among chloritoid, taramite, chlorite, paragonite, garnet and quartz. These P-T conditions are distinctly lower than those estimated for a chloritoid-bearing assemblage at the eclogite facies stage of pelitic schists in the Seba eclogite unit (1.7 GPa/525-555°C), 0.5-1 km north of the Ikadadu outcrop. This implies that there is a significant difference in the peak metamorphic pressure of the chloritoid-forming stages between the Ikadadu and Seba chloritoid-bearing schists, indicating the existence of a tectonic discontinuity between the two localities. Chloritoid and amphibole-bearing assemblages are stable at various metamorphic P-T conditions within suitable bulk rock compositions and their phase equilibria are helpful in discussing P-T conditions for various metamorphic rocks.

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Details 詳細情報について

  • CRID
    1390001206546249600
  • NII Article ID
    10014010488
  • NII Book ID
    AA11460926
  • DOI
    10.2465/jmps.100.43
  • BIBCODE
    2005JMPeS.100...43K
  • COI
    1:CAS:528:DC%2BD2MXltlSis7s%3D
  • ISSN
    13493825
    13456296
  • Text Lang
    en
  • Data Source
    • JaLC
    • Crossref
    • CiNii Articles
  • Abstract License Flag
    Disallowed

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