Nahcolite in fluid inclusions from the Ryoke metamorphic rocks and its implication for fluid genesis

DOI 被引用文献1件 参考文献43件

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Nahcolite (NaHCO3) has been found in fluid inclusions in quartz veins hosted by the Ryoke metamorphic rocks in Kasado-Jima (Island), Yamaguchi Prefecture, Japan. The inclusions are classified into three types: type 1 containing vapor +/− liquid of the H2O-NaCl-CO2-CH4 system, type 2 of H2O-NaCl fluids and type 3 with nahcolite solid. Salinities of the nahcolite-bearing fluids are lower than 4 wt% NaCl eq. Extremely large volume fractions of nahcolite solids, occupying more than 50% of total inclusion volume, and various fluid compositions are indicative of their origin as accidentally trapped ones while the fluids were immiscible below the nahcolite melting temperature (270 °C). A thermodynamic calculation of the nahcolite stability and a phase analysis of the fluids show logaNa+ = 7.4 − pH as the minimum activity at P = 100 MPa and T = 270 °C where the neutral pH = 5.6. Hence, it can be concluded that the original (prior to immiscible state) liquids might have contained high Na+ and low Cl− yielded by an interaction of a low-salinity fluid and Na-bearing minerals such as plagioclase in the host metamorphic rocks below the fractures now occupied by quartz if nahcolite precipitated from boiling fluids.

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詳細情報 詳細情報について

  • CRID
    1390001206545532416
  • NII論文ID
    10018106117
  • NII書誌ID
    AA11460926
  • DOI
    10.2465/jmps.101.254
  • COI
    1:CAS:528:DC%2BD2sXhtVGnug%3D%3D
  • ISSN
    13493825
    13456296
  • 本文言語コード
    en
  • データソース種別
    • JaLC
    • Crossref
    • CiNii Articles
  • 抄録ライセンスフラグ
    使用不可

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