Frysinger Glenn S.

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Frysinger
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Glenn S.
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Start date: 2006 × End date: 2008 × Author: Nelson, Robert K. ×

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Preprint

Molecular evidence of Late Archean archaea and the presence of a subsurface hydrothermal biosphere

2006-12-13 , Ventura, Gregory T. , Kenig, Fabien , Reddy, Christopher M. , Schieber, Juergen , Frysinger, Glenn S. , Nelson, Robert K. , Dinel, Etienne , Gaines, Richard B. , Schaeffer, Philippe

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.

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Preprint

Analysis of unresolved complex mixtures of hydrocarbons extracted from Late Archean sediments by comprehensive two-dimensional gas chromatography (GC×GC)

2008-03 , Ventura, Gregory T. , Kenig, Fabien , Reddy, Christopher M. , Frysinger, Glenn S. , Nelson, Robert K. , Van Mooy, Benjamin A. S. , Gaines, Richard B.

Hydrocarbon mixtures too complex to resolve by traditional capillary gas chromatrography display gas chromatograms with dramatically rising baselines or “humps” of coeluting compounds that are termed unresolved complex mixtures (UCMs). Because the constituents of UCMs are not ordinarily identified, a large amount of geochemical information is never explored. Gas chromatograms of saturated/unsaturated hydrocarbons extracted from Late Archean argillites and greywackes of the southern Abitibi Province of Ontario, Canada contain UCMs with different appearances or “topologies” relating to the intensity and retention time of the compounds comprising the UCMs. These topologies appear to have some level of stratigraphic organization, such that samples collected at any stratigraphic formation collectively are dominated by UCMs that either elute early- (within a window of C15-C20 of n-alkanes), early- to mid- (C15-C30 of n-alkanes), or have a broad UCM that extends through the entire retention time of the sample (from C15-C42 of n-alkanes). Comprehensive two-dimensional gas chromatography time-of-flight mass spectrometry (GC×GC-MS) was used to resolve the constituents forming these various UCMs. Early- to mid- eluting UCMs are dominated by configurational isomers of alkyl-substituted and non substituted polycyclic compounds that contain up to six rings. Late eluting UCMs are composed of C36-C40 mono-, bi-, and tricyclic archaeal isoprenoid diastereomers. Broad UCMs spanning the retention time of compound elution contain nearly the same compounds observed in the early-, mid-, and late retention time UCMs. Although the origin of the polycyclic compounds is unclear, the variations in the UCM topology appear to depend on the concentration of initial compound classes that have the potential to become isomerized. Isomerization of these constituents may have resulted from hydrothermal alteration of organic matter.

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