Publication Date:
2022-05-26
Description:
Author Posting. © National Academy of Sciences of the USA, 2007. This is the author's version of the work. It is posted here by permission of National Academy of Sciences of the USA for personal use, not for redistribution. The definitive version was published in Proceedings of the National Academy of Sciences 104 (2007): 14260-14265, doi:10.1073/pnas.0610903104.
Description:
Highly cracked and isomerized archaeal lipids and bacterial lipids, structurally changed
by thermal stress, are present in solvent extracts of 2,707-2,685 million year old (Ma)
metasedimentary rocks from Timmins, Ontario, Canada. These lipids appear in
conventional gas chromatograms as unresolved complex mixtures (UCMs) and include
cyclic and acyclic biphytanes, C36-C39 derivatives of the biphytanes, and C31-C35
extended hopanes. Biphytane and extended hopanes are also found in high pressure
catalytic hydrogenation (HPCH) products released from solvent-extracted sediments,indicating that archaea and bacteria were present in Late Archean sedimentary
environments. Post-depositional, hydrothermal gold mineralization and graphite
precipitation occurred prior to metamorphism (~2,665 Ma). Late Archean metamorphism
significantly reduced the kerogen’s adsorptive capacity and severely restricted sediment
porosity, limiting the potential for post-Archean additions of organic matter to the
samples. Argillites exposed to hydrothermal gold mineralization have disproportionately
high concentrations of extractable archaeal and bacterial lipids relative to what is
releasable from their respective HPCH product and what is observed for argillites
deposited away from these hydrothermal settings. The addition of these lipids to the
sediments likely results from a Late Archean subsurface hydrothermal biosphere of
archaea and bacteria.
Description:
This project was supported by NASA Exobiology grant #NAG5-13446 to Fabien Kenig.
SEM analysis was supported by NSF grant EAR 0318769 to Juergen Schieber. GC×GC
analysis was supported by NSF grant IIS-0430835 and the Seaver Foundation to
Christopher M. Reddy.
Repository Name:
Woods Hole Open Access Server
Type:
Preprint
Format:
application/pdf
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