Carbonic fluid inclusions in a garnet–pyroxene granulite from Austhovde in the Lützow–Holm Complex, East Antarctica: Implications for a decompressional <i>P–T</i> path

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著者

    • TAKAHASHI Kazuki
    • Graduate School of Life and Environmental Sciences, University of Tsukuba
    • TSUNOGAE Toshiaki
    • Graduate School of Life and Environmental Sciences, University of Tsukuba|Department of Geology, University of Johannesburg

抄録

<p>A garnet–pyroxene granulite from Austhovde in the Lützow–Holm Complex, East Antarctica, contains two types of fluid inclusions: a small number of primary inclusions in garnet and quartz, and dominant secondary inclusions in garnet and plagioclase. The melting temperatures of the trapped fluids lie in a range of −57.2 to −56.4 °C, which are close to the triple–point temperature of pure CO<sub>2</sub>. The primary inclusions are homogenized at +1.8 to +12.6 °C, which correspond to densities of 0.842–0.917 g/cm<sup>3</sup>. However, the estimated pressure conditions (3–5 kbar at 850 °C) from the fluid densities of the primary inclusions are not consistent with the peak <i>P–T</i> conditions recorded in the rock (840–860 °C and 8.3–8.7 kbar). Homogenization of the secondary inclusions into the liquid phase occurs within a range of +11.5 to +25.2 °C, which correspond to low CO<sub>2</sub> densities of 0.708 to 0.851 g/cm<sup>3</sup>. The results imply that fluid density decreased by partial leakage of the trapped fluid in the primary inclusions during post–peak exhumation stage, and the process is consistent with the occurrence of orthopyroxene + hornblende + plagioclase symplectite around garnet, suggesting post–peak rapid decompression.</p>

収録刊行物

  • 岩石礦物礦床學

    岩石礦物礦床學 112(3), 132-137, 2017

    一般社団法人 日本鉱物科学会

各種コード

  • NII論文ID(NAID)
    130007348398
  • 本文言語コード
    ENG
  • ISSN
    1345-6296
  • データ提供元
    J-STAGE 
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