Acyclic isoprenoids – molecular indicators of archaeal activity in contemporary and ancient Chinese saline/hypersaline environments |
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Authors: | Wang Ruiliang |
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Institution: | (1) Biogeochemical Laboratories, Department of Geological Sciences, Indiana University, Bloomington, In, 47405-1403, U.S.A |
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Abstract: | Acyclic isoprenoid hydrocarbons are found to be the predominant components in the organic matter extracted from sedimentary
cores and oils of various hypersaline settings, including Tertiary Janghan salt lake basin, Cretaceous Taian salt lake basin,
and Triassic, Permian and Cambrian Yangtze evaporitic marine platform. Inland saline lake basins are characterized by tremendous
predominance of phytane (iC20) ranging up to 15% of the total extract. While the evaporitic marine sediments are unique for
their complete series of super-long-chain acyclic isoprenoids, up to C40. These isoprenoids possess head-to-head, tail-to-tail
or regular linkages and generally are indicators of the significant contribution from various archaea (archaebacteria), i.e.
halophiles, methanogens and acidothermophiles. According to the great discrepancy of distribution and composition of isoprenoids,
these modern and Cenozoic inland salt lake sediments are likely dominated by halophilic archaea, while the studied Mesozoic
and Paleozoic evaporitic marine sediments are predominantly distinguished by methanogens and acidothermophiles. Concentration
of chlorine salt is more directly proportional to the abundance of phytane than sulfate. Reduced species of sulfur, sulfide,
S0 and organic sulfur compounds (OSC), however, may have played a key role in the preservation and formation of the highly
abundant phytane observed in the inland salt lake basins.
This revised version was published online in July 2006 with corrections to the Cover Date. |
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Keywords: | Archaea archaebacteria biomarker isoprenoid salinity paleoenvironment Cambrian Permian Triassic Eocene |
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