Document Detail

Compound-specific isotopic analyses: a novel tool for reconstruction of ancient biogeochemical processes.
MedLine Citation:
PMID:  11540919     Owner:  NASA     Status:  MEDLINE    
Patterns of isotopic fractionation in biogeochemical processes are reviewed and it is suggested that isotopic fractionations will be small when substrates are large. If so, isotopic compositions of biomarkers will reflect those of their biosynthetic precursors. This prediction is tested by consideration of results of analyses of geoporphyrins and geolipids from the Greenhorn Formation (Cretaceous, Western Interior Seaway of North America) and the Messel Shale (Eocene, lacustrine, southern Germany). It is shown (i) that isotopic compositions of porphyrins that are related to a common source, but which have been altered structurally, cluster tightly and (ii) that isotopic differences between geolipids and porphyrins related to a common source are equal to those observed in modern biosynthetic products. Both of these observations are consistent with preservation of biologically controlled isotopic compositions during diagenesis. Isotopic compositions of individual compounds can thus be interpreted in terms of biogeochemical processes in ancient depositional environments. In the Cretaceous samples, isotopic compositions of n-alkanes are covariant with those of total organic carbon, while delta values for pristane and phytane are covariant with those of porphyrins. In this unit representing an open marine environment, the preserved acyclic polyisoprenoids apparently derive mainly from primary material, while the extractable, n-alkanes derive mainly from lower levels of the food chain. In the Messel Shale, isotopic compositions of individual biomarkers range from -20.9 to -73.4% vs PDB. Isotopic compositions of specific compounds can be interpreted in terms of origin from methylotrophic, chemautotrophic, and chemolithotrophic microorganisms as well as from primary producers that lived in the water column and sediments of this ancient lake.
J M Hayes; K H Freeman; B N Popp; C H Hoham
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Publication Detail:
Type:  Journal Article; Research Support, Non-U.S. Gov't; Research Support, U.S. Gov't, Non-P.H.S.    
Journal Detail:
Title:  Organic geochemistry     Volume:  16     ISSN:  0146-6380     ISO Abbreviation:  Org. Geochem.     Publication Date:  1990  
Date Detail:
Created Date:  1998-08-28     Completed Date:  1998-08-28     Revised Date:  2007-08-01    
Medline Journal Info:
Nlm Unique ID:  100971475     Medline TA:  Org Geochem     Country:  ENGLAND    
Other Details:
Languages:  eng     Pagination:  1115-28     Citation Subset:  S    
Department of Chemistry, Indiana University, Bloomington 47405, USA.
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MeSH Terms
Alkanes / analysis,  chemistry
Carbon / analysis,  chemistry*,  metabolism
Carbon Dioxide / analysis,  chemistry,  metabolism
Carbon Isotopes*
Carbonates / analysis,  chemistry,  metabolism
Diterpenes / analysis,  chemistry,  metabolism
Geologic Sediments / chemistry*,  microbiology
Lipids / analysis*,  biosynthesis,  chemistry
Porphyrins / analysis*,  biosynthesis,  chemistry
Pyrroles / analysis,  chemistry
Terpenes / analysis,  chemistry,  metabolism
Water Microbiology*
Reg. No./Substance:
0/Alkanes; 0/Carbon Isotopes; 0/Carbonates; 0/Diterpenes; 0/Lipids; 0/Porphyrins; 0/Pyrroles; 0/Terpenes; 0/Tetrapyrroles; 124-38-9/Carbon Dioxide; 1921-70-6/pristane; 638-36-8/phytane; 7440-44-0/Carbon
J M Hayes / IN U, Bloomington

From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine

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