Mantle helium signal in the West Carpathians, Poland

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Abstract

Mantle derived helium with R/R<sub>AM</sub> ratios up to 1, which accompanies CO<sub>2</sub> exhalations and cold CO<sub>2</sub>-rich carbonated waters, has been found to escape through the 40 km thick continental lithosphere in the Outer Carpathians. Revised <sup>4</sup>He/<sup>20</sup>Ne ratios of mantle and crust (6818 and 2.53 × 10<sup>7</sup>, respectively) allow the estimation of the respective contribution of mantle, crust and air-derived helium to the bulk helium. Although isotopic ratios of noble gases attest to a mixing process which takes place between crust and mantle gases, carbon isotope ratios of the CO<sub>2</sub> (δ<sup>13</sup>C of -8.9 to -1.8 per mil) do not correlate with helium isotope ratios (R/R<sub>A</sub>), indicating complex processes of CO<sub>2</sub> derivation. The R/R<sub>A</sub> ratios in methane-dominated gases are similar to those in CO<sub>2</sub>-rich gases, designating similar mode of helium supply. The CO<sub>2</sub>/<sup>3</sup>He ratios are up to 2 orders of magnitude higher than the secular CO<sub>2</sub>/<sup>3</sup>He ratio of mantle gas emanations at ocean ridges. It suggests that the recycled crustal carbon rather than mantle carbon is the principal source of CO<sub>2</sub>. The fluids of interest with their noble gases and other isotopic signatures and high concentrations of dissolved carbonates are similar to hydrothermal solutions observed in active marginal basins.

Journal

  • GEOCHEMICAL JOURNAL

    GEOCHEMICAL JOURNAL 31(6), 383-394, 1997-12-01

    GEOCHEMICAL SOCIETY OF JAPAN

References:  43

Codes

  • NII Article ID (NAID)
    10008802126
  • NII NACSIS-CAT ID (NCID)
    AA00654975
  • Text Lang
    ENG
  • Article Type
    ART
  • ISSN
    00167002
  • NDL Article ID
    4371294
  • NDL Source Classification
    ZM41(科学技術--地球科学)
  • NDL Call No.
    Z53-R488
  • Data Source
    CJP  NDL  J-STAGE 
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