Elsevier

Gondwana Research

Volume 5, Issue 4, October 2002, Pages 823-835
Gondwana Research

Granulite Facies Relics in the Early Paleozoic Kyanite-bearing Ultrabasic Metacumulate in the Oeyama Belt, the Inner Zone of Southwestern Japan

https://doi.org/10.1016/S1342-937X(05)70916-3Get rights and content

Abstract

Granulite facies relics are found in the early Paleozoic kyanite-bearing melanocratic metagabbro from the Fuko Pass metacumulate mass of the Oeyama belt, southwestern Japan. The granulite facies assemblage consists of relict Al-rich clinopyroxene (up to 8.5 wt.% Al2O3) and pseudomorphs of spinel and plagioclase. The spinel pseudomorphs consist mainly of symplectic intergrowth of corundum and magnetite with minor gahnitic spinel. The plagioclase pseudomorphs are composed mainly of clinozoisite with minor kyanite. The symplectite suggests oxidation and Mg-depletion of the original spinel: hercynite (3FeAl2O4)+(O) = corundum (3Al2O3)+magnetite (Fe3O4). This oxidation reaction may have taken place at 700-900°C temperature. The melanocratic metagabbro has later been hydrated to form the epidote amphibolite assemblage represented by clinozoisite+kyanite+paragonite. The clinozoisite+kyanite assemblage has further reacted to form margarite at a lower temperature. The first granulite facies assemblage implies that the metacumulate has originally constituted a basal part of thick oceanic crust, and then has experienced the high-P/T type metamorphism in a subduction zone. This indicates that the thick oceanic crust has been formed and accreted to the Circum-Pacific orogenic belt in the early Paleozoic time.

References (51)

  • CloosM.

    Lithospheric buoyancy and collisional orogenesis: subduction of oceanic plateaus, continental margins, island arcs, spreading ridges, and seamounts

    Geol. Soc. Amer. Bull.

    (1993)
  • DasguptaS. et al.

    Mid-crustal contact metamorphism around the Chimakurthy mafic-ultramafic complex, Eastern Ghats Belt, India

    Contrib. Mineral. Petrol.

    (1997)
  • DeBariS.M. et al.

    Examination of the deep levels of an island arc: evidence from the Tonsina ultramafic-mafic assemblage, Tonsina, Alaska

    J. Geophys. Res.

    (1989)
  • FrancisD.M.

    Corona-bearing pyroxene granulite xenoliths and the lower crust beneath Nunivak Island, Alaska

    Can. Mineral.

    (1976)
  • GasparikT.

    Two-pyroxenes thermobarometry with new experimental data in the system CaO-MgO-Al2O3-SiO2

    Contrib. Mineral. Petrol.

    (1984)
  • Gil IbarguchiJ.I. et al.

    Mg- and Cr-rich staurolite and Cr-rich kyanite in high-pressure ultrabasic rocks (Cabo Ortegal, northwestern Spain)

    Amer. Mineral.

    (1991)
  • GrégoireM. et al.

    The meta-igneous granulite xenoliths from Kerguelen Archipelago: evidence of a continent nucleation in an oceanic setting

    Contrib. Mineral. Petrol.

    (1998)
  • GrégoireM. et al.

    Oceanic granulite from the Kerguelen Archipelago

    Nature

    (1994)
  • Hayasaka, Y., Sugimoto, T., Kano, T., (1995) Ophiolitic complex and metamorphic rocks in the Niimi-Katsuyama area,...
  • HollandT.J.B. et al.

    An internally consistent thermodynamic data set for phases of petrological interest

    J. Metam. Geol.

    (1998)
  • IshigaH. et al.

    Late Paleozoic radiolarian assemblages from the Shimomidani Formation in Akiyoshi terrane, southwest Japan

    J. Geol. Soc. Japan

    (1988)
  • IshiwatariA.

    Granulite-facies metacumulates of the Yakuno ophiolite, Japan: evidence for unusually thick oceanic crust

    J. Petrol.

    (1985)
  • IshiwatariA.

    Igneous petrogenesis of the Yakuno ophiolite (Japan) in the context of the diversity of ophiolites

    Contrib. Mineral. Petrol.

    (1985)
  • Ishiwatari, A., (1991) Time-space distribution and petrologic diversity of Japanese ophiolite In: Peters, Tj., et. al.,...
  • IsozakiY.

    Anatomy and genesis of a subduction-related orogen: a new view of geotectonic subdivision and evolution of the Japanese Island

    The Island Arc

    (1996)
  • Cited by (11)

    • Reappraisal of the oldest high-pressure type schist in Japan: New zircon U-Pb age of the Kitomyo Schist of the Kurosegawa Belt

      2021, Lithos
      Citation Excerpt :

      Although the Fuko Pass Metacumulates bears a mineralogical indication of HP metamorphism most likely having occurred in ‘proto-Japan’ margin, their protolith, mainly troctolitic igneous cumulates, is not typical of ‘Pacific-type’ subduction complexes. The Fuko Pass protolith geochemistry as well as the presence of spinel granulite-facies relict minerals suggest an unusually thick oceanic plateau (Tsujimori & Ishiwatari, 2002). In contrast, the Kitomyo Schist has a typical accretionary complex protolith consisting of metabasaltic and metasedimentary rocks.

    • Orogenic and metamorphic processes in plate boundaries: Synopsis and future directions

      2022, Japanese Magazine of Mineralogical and Petrological Sciences
    View all citing articles on Scopus
    View full text