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Selective chemical degradation of silica sinters of the Taupo Volcanic Zone (New Zealand). Implications for early Earth and Astrobiology

Research output: Contribution to journalArticle

Original languageEnglish
Pages (from-to)449-464
Number of pages16
JournalGeobiology
Volume17
Issue number4
Early online date24 Apr 2019
DOIs
DateAccepted/In press - 21 Mar 2019
DateE-pub ahead of print - 24 Apr 2019
DatePublished (current) - 1 Jul 2019

Abstract

Most organic matter (OM) on Earth occurs as kerogen-like materials, that is naturally formed macromolecules insoluble with standard organic solvents. The formation of this insoluble organic matter (IOM) is a topic of much interest, especially when it limits the detection of compounds of geomicrobiological interest. For example, studies that search for biomarker evidence of life on early Earth or other planets usually use solvent-based extractions. This leaves behind a pool of OM as unexplored post-extraction residues, potentially containing diagnostic biomarkers. Since the IOM has an enhanced potential for preservation compared to soluble OM, analysing IOM-released biomarkers can also provide even deeper insights into the ecology of ancient settings, with implications for early Earth and Astrobiology investigations. Here, we analyse the prokaryotic lipid biosignature within soluble and IOM of the Taupo Volcanic Zone (TVZ) silica sinters, which are key analogues in the search for life. We apply sequential solvent extractions and a selective chemical degradation upon the post-solvent extraction residue. Moreover, we compare the IOM from TVZ sinters to analogous studies on peat and marine sediments to assess patterns in OM insolubilisation across the geosphere. Consistent with previous work, we find significant but variable proportions—1%–45% of the total prokaryotic lipids recovered—associated with IOM fractions. This occurs even in recently formed silica sinters, likely indicating inherent cell insolubility. Moreover, archaeal lipids seem more prone to insolubilisation as compared to the bacterial analogues, which might enhance their preservation and also bias overall biomarkers interpretation. These observations are similar to those observed in other settings, confirming that even in a setting where the OM derives predominantly from prokaryotic sources, patterns of IOM formation/occurrence are conserved. Differences with other settings, however, such as the occurrence of archaeol in IOM fractions, could be indicative of different mechanisms for IOM formation that merit further exploration.

    Research areas

  • Astrobiology, early Earth, prokaryotic membrane lipids, selective chemical degradation, silica sinters, Taupo Volcanic Zone

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  • Full-text PDF (accepted author manuscript)

    Rights statement: This is the accepted author manuscript (AAM). The final published version (version of record) is available online via Wiley at https://doi.org/10.1111/gbi.12340 . Please refer to any applicable terms of use of the publisher.

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  • Full-text PDF Supplementary Material (accepted author manuscript)

    Rights statement: This is the accepted author manuscript (AAM). The final published version (version of record) is available online via Wiley at https://doi.org/10.1111/gbi.12340 . Please refer to any applicable terms of use of the publisher.

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    Rights statement: This is the accepted author manuscript (AAM). The final published version (version of record) is available online via Wiley at https://doi.org/10.1111/gbi.12340 . Please refer to any applicable terms of use of the publisher.

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  • Full-text PDF Supplementary Material (accepted author manuscript)

    Rights statement: This is the accepted author manuscript (AAM). The final published version (version of record) is available online via Wiley at https://doi.org/10.1111/gbi.12340 . Please refer to any applicable terms of use of the publisher.

    Accepted author manuscript, 1 MB, PDF document

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    Licence: Other

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