Compound-specific isotopic analyses: A novel tool for reconstruction of ancient biogeochemical processes

doi:10.1016/0146-6380(90)90147-R

Organic Geochemistry

Volume 16, Issues 4–6, 1990, Pages 1115-1128

https://doi.org/10.1016/0146-6380(90)90147-R Get rights and content

Abstract

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 δ values for pristane and phytane are covariant with those of poryphyrins. 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, chemoautotrophic, and chemolithotrophic microorganisms as well as from primary producers that lived in the water column and sediments of this ancient lake.

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^∗: Present address: Department of Geology and Geophysics, University of Hawaii, 2525 Correa Road, Honolulu, HI 96822, U.S.A.

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Isotopic organic chemistryCompound-specific isotopic analyses: A novel tool for reconstruction of ancient biogeochemical processes

Abstract

Org. Geochem.

Geochim. Cosmochim. Acta

Geochim. Cosmochim. Acta

Geochim. Cosmochim. Acta

Geochim. Cosmochim. Acta

Geochim. Cosmochim. Acta

Chem. Geol.

J. Theor. Biol.

FEMS Microbiol. Lett.

Anomalous 13C enrichment in modern marine organic carbon

Nature

Geochemical and climatic effects of increased marine organic carbon burial at the Cenomanian/Turonian boundary

Nature

Poryphyrins in the geological record

An investigation of 2H and 13C abundance in a sequence of related oils of increasing maturity

Conversion efficiencies in heterotrophic organisms

Biol. Rev. Cambridge Phil. Soc.

Petroporyphyrins

Petroporphyrins as indicators of geothermal maturation

Nature

The etioporphyrins of oil Shale: Structural evidence for their derivation from chlorophyll

J. Chem. Soc. Chem. Commun.

Evidence from GC-MS carbon-isotopic measurements for multiple origins of sedimentary hydrocarbons

Nature

Isotopic compositions and probable origins of organic molecules in the Eocene Messel Shale

Nature

Isotopic organic chemistry
Compound-specific isotopic analyses: A novel tool for reconstruction of ancient biogeochemical processes

Anomalous ¹³C enrichment in modern marine organic carbon

An investigation of ²H and ¹³C abundance in a sequence of related oils of increasing maturity