Hydrocarbon biomarkers from Ordovician sediments and the fossil alga Gloeocapsomorpha prisca Zalessky 1917

Journal Article · Thu Oct 01 04:00:00 EDT 1987 · Geochimica et Cosmochimica Acta; (USA)

DOI:https://doi.org/10.1016/0016-7037(87)90149-9· OSTI ID:7270650

Hoffmann, C F; Powell, T G; Summons, R E ^[1]; Foster, C B ^[2]

---

1. Bureau of Mineral Resources, Canberra City (Australia)
2. Western Mining Corp. Ltd., Parkside (Australia)

Numerous Ordovician oils worldwide are known to show unusual and distinctive distributions of hydrocarbons which, it has been suggested, are derived from a unique benthonic mat-forming non-photosynthetic prokaryotic organism, Gloeocapsomorpha prisca Zalessky 1917, which is the major contributor of organic matter. Organic matter-rich sediments from the canning and Amadeus basins of Australia, known to contain G. prisca fossils and to have the characteristic predominance of odd carbon number (C{sub 13}-C{sub 19}) n-alkanes, were investigated to determine other hydrocarbon distributions. Sediments from both basins contained abundant n-alkylcyclohexanes with odd carbon number predominance (C{sub 13}-C{sub 19}) and methyl-n-alkylcyclohexanes (C{sub 14}-C{sub 20}) which, in immature sediments, showed an even carbon number predominance. The isomer distribution of these latter compounds was determined by direct comparison with synthetic standards. Pyrolysis of a G. prisca-rich kerogen yielded a hydrocarbon mixture with a similar composition to the sediment extract, except that there was a marked increase in the relative abundance of pristane, phytane, alkylcyclohexanes, steranes and hopanes relative to n-alkanes. They argue on the basis of the geological, geochemical and palynological data that G. prisca was probably planktonic, photosynthetic and very possibly eukaryotic and that the striking character of Ordovician oils and sediments derive from bacterial and other diagenetic imprints superimposed on the primary signature of this organism.

• OSTI ID: 7270650
• Journal Information: Geochimica et Cosmochimica Acta; (USA), Journal Name: Geochimica et Cosmochimica Acta; (USA) Vol. 51:10; ISSN GCACA; ISSN 0016-7037
• Country of Publication: United States
• Language: English

Related Subjects

02 PETROLEUM
020200* -- Petroleum-- Reserves
Geology
& Exploration
023000 -- Petroleum-- Properties & Composition
58 GEOSCIENCES
580000 -- Geosciences
ALGAE
AUSTRALASIA
AUSTRALIA
BIOLOGICAL MARKERS
BITUMINOUS MATERIALS
CARBONACEOUS MATERIALS
CHEMICAL COMPOSITION
CHEMISTRY
DIAGENESIS
ENERGY SOURCES
FOSSIL FUELS
FUELS
GAMETES
GEOCHEMISTRY
GEOLOGIC AGES
GEOLOGIC DEPOSITS
GEOLOGIC STRUCTURES
GERM CELLS
HYDROCARBONS
KEROGEN
MATERIALS
MINERAL RESOURCES
ORDOVICIAN PERIOD
ORGANIC COMPOUNDS
ORGANIC MATTER
PALEOZOIC ERA
PALYNOLOGY
PETROLEUM
PETROLEUM DEPOSITS
PLANTS
POLLEN
RESOURCES
SEDIMENTARY BASINS
SEDIMENTS