Biomarkers as Paleoenvironmental Proxies
2010 Fall Meeting Search Results
11/12/13 9:07 PM
Cite abstracts as Author(s) (2010), Title, Abstract xxxxx-xxxx presented at 2010 Fall Meeting, AGU, San Francisco, Calif., 13-17 Dec.
Your query was: brassell HR: 1020h AN: PP42A-01 TI: Biomarkers as Paleoenvironmental Proxies AU: *Brassell, S C EM:
[email protected] AF: Geological Sciences, Indiana University, Bloomington, IN, USA AB: A diverse array of source-specific biomarkers, often coupled with diagnostic isotopic compositions, can provide compelling evidence of varied contributions to sediments from Archaea, bacteria, discrete algal groups and vascular plants. Production of these diagnostic compounds is intrinsically linked to environmental factors that affect their source organisms, notably the supply of nutrients and essential elements, and the survival and preservation of such biomarkers is dependent on depositional conditions, including oxygenation levels prevailing in the water column and underlying sediment. Deciphering the complex signatures resulting from these distinct controls presents many challenges, especially assessment of the nature, magnitude, and temporal variations in productivity, which are typically interwoven in ancient molecular records. The biomarker compositions of marine sediments deposited during Mesozoic Oceanic Anoxic Events (OAEs) reveal differences in ocean productivity on both local and regional scales. Thus, 2-methylhopanoid biomarkers derived from cyanobacteria are prominent constituents in Lower Aptian (OAE1a) sediments, accompanied by δ15N values evidence for nitrogen fixation, whereas the prevalence of 28,30-bisnorhopane in Cenomanian/Turonian sediments from Tethys and Brazilian marginal basins suggests a distinct ecological niche for their bacterial source organisms during OAE2. These varied molecular records for OAEs attest to temporal differences in marine phytoplankton communities, augmented by biomarker evidence for dynamic fluctuations in redox conditions over short, perhaps seasonal, time scales during these episodes. DE: [0420] BIOGEOSCIENCES / Biomolecular and chemical tracers DE: [1051] GEOCHEMISTRY / Sedimentary geochemistry DE: [1055] GEOCHEMISTRY / Organic and biogenic geochemistry DE: [4924] PALEOCEANOGRAPHY / Geochemical tracers SC: Paleoceanography and Paleoclimatology (PP) MN: 2010 Fall Meeting New Search AGU Home
http://www.agu.org/cgi-bin/SFgate/SFgate?language=English&verbose…012%2047477709%20%2fdata2%2fepubs%2fwais%2fdata%2ffm10%2ffm10.txt
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