Polymetamorphism of Aktyuz eclogites (northern Kyrgyz Tien-Shan) deduced from inclusions in garnets

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Abstract

Garnet and omphacite in eclogites from the Aktyuz area, northern Kyrgyz Tien-Shan, preserve evidence of two distinct metamorphic events. Relic polyphase inclusions of Fe-rich staurolite (XMg < 0.29), Mg-taramite, paragonite, and oligoclase (An < 16) contained in garnet cores represent a separate pre-eclogitic amphibolite or epidote-amphibolite facies metamorphism (T = 560-650 °C, P = 4-10 kbar). This relatively low- to medium-pressure metamorphic event probably resulted from the heat of the hot hanging wall at the inception of subduction. Inclusions in the garnet cores and rims and matrix omphacite (glaucophane, sodic-calcic and calcic amphiboles, paragonite, phengite, epidote, albite, rutile, hematite, and quartz) suggest that epidote-blueschist facies conditions (T = 330-570 °C, P = 8-16 kbar) were experienced during the prograde stage of the eclogitic metamorphism. This event occurred within a subduction zone. The estimated peak metamorphic conditions of the eclogites are T = 600-710 °C and P = 15-25 kbar. The subsequent retrograde path through epidote-amphibolite and greenschist facies suggests a clockwise P-T path, in contrast to the anticlockwise P-T path proposed by previous work.

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Details 詳細情報について

  • CRID
    1390001206545864704
  • NII Article ID
    10018419236
  • NII Book ID
    AA11460926
  • DOI
    10.2465/jmps.060831b
  • BIBCODE
    2007JMPeS.102..150O
  • COI
    1:CAS:528:DC%2BD2sXmtlSrurg%3D
  • ISSN
    13493825
    13456296
  • Text Lang
    en
  • Data Source
    • JaLC
    • Crossref
    • CiNii Articles
  • Abstract License Flag
    Disallowed

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