Interpreting Molecular and Isotopic Biosignatures in Methane-Derived Authigenic Carbonates in the Light of a Potential Carbon Cycle in the Icy Moons.

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  • Additional Information
    • Source:
      Publisher: Mary Ann Liebert, Inc Country of Publication: United States NLM ID: 101088083 Publication Model: Print-Electronic Cited Medium: Internet ISSN: 1557-8070 (Electronic) Linking ISSN: 15578070 NLM ISO Abbreviation: Astrobiology Subsets: MEDLINE
    • Publication Information:
      Original Publication: Larchmont, N.Y. : Mary Ann Liebert, Inc., c2001-
    • Subject Terms:
      Methane*/metabolism ; Moon*; Archaea/metabolism ; Biomarkers/metabolism ; Carbon ; Carbon Cycle ; Carbonates ; Geologic Sediments/microbiology ; Lipids ; Oxidation-Reduction ; Water
    • Abstract:
      Finding evidence of life beyond Earth is the aim of future space missions to icy moons. Icy worlds with an ocean underlying the icy crust and in contact with a rocky subsurface have great astrobiological interest due to the potential for water-rock interactions that may provide a source of nutrients necessary to sustain life. Such water-rock interactions in icy moons can be indirectly investigated using analogous environments on the deep seafloor on Earth. Here, we investigate the presence of molecular and isotopic biomarkers in two submarine cold seep systems with intense rock-fluid interactions and carbon sink as carbonates with the aim of gaining understanding of potential carbon cycles in the icy worlds' oceans. Authigenic carbonates associated to cold seeps (a chimney from the Gulf of Cádiz and a clathrite from the Pacific Hydrate Ridge) were investigated for their mineralogical composition and lipid biomarker distribution. Molecular and compound-specific isotopic composition of lipid biomarkers allowed us to infer different carbonate origins in both carbonate scenarios: biogenic methane (clathrite) versus thermogenic methane together with allochthonous carbon (chimney). In the Pacific cold seep, carbonate precipitation of the clathrite was deduced to result from the anaerobic oxidation of methane by syntrophic action of methanotrophic archaea with sulfate-reducing bacteria. The distinct carbon sources (thermogenic methane, pelagic biomass, etc.) and sinks (gas clathrates, clathrite, chimney carbonates) were discussed in the light of potentially similar carbon cycling pathways in analogous icy-moon oceans. We show how the isotopic analysis of carbon may be crucial for detecting biosignatures in icy-world carbon sinks. These considerations may affect the strategy of searching for biosignatures in future space missions to the icy worlds.
    • Contributed Indexing:
      Keywords: Anaerobic oxidation of methane; Archaea; Clathrate hydrates; Cold seeps; Icy worlds; Lipid biomarkers; Stable-carbon isotope analysis; Sulfate-reducing bacteria
    • Accession Number:
      0 (Biomarkers)
      0 (Carbonates)
      0 (Lipids)
      059QF0KO0R (Water)
      7440-44-0 (Carbon)
      OP0UW79H66 (Methane)
    • Publication Date:
      Date Created: 20220324 Date Completed: 20220512 Latest Revision: 20220627
    • Publication Date:
      20240104
    • Accession Number:
      10.1089/ast.2021.0036
    • Accession Number:
      35325553