Carbon isotope biogeochemistry of plant resins and derived hydrocarbons
Carbon isotope biogeochemistry of plant resins and derived hydrocarbons
- Org. Geochem., 29(5-7), p.1199-1214, 1998 .
Hydrocarbons derived from plant resins are major components of some terrigenous oils and bitumens. These compounds are structurally distinct and this makes them useful biomarkers applicable in petroleum exploration as well as sources of biogeochemical information about palaeoenvironment and palaeobotany. Although recent studies have elucidated the molecular structure of resinites, very lit- tle information has been available for the carbon isotope composition of resinites and no studies of resin-derived compounds in oils had been performed prior to the present study. Hence, carbon stable isotope analyses were carried out on a suite of modern and fossil resins of diverse origins, including compound speci®c isotope analysis of individual hydrocarbons produced during resin pyrolysis. Oils de- rived from resinitic source organic matter were also analysed. The results showed that ``Class I'' resi- nites derived from gymnosperms were enriched in the heavy carbon isotope compared with those from angiosperms (``Class II'' resinites). Furthermore, both fossil resinites themselves and individual hydro- carbons derived from them were isotopically heavy compared with modern plant resins. The isotopic signatures of diterpanes and triterpanes in various early Tertiary oils from Australasia and Southeast Asia re¯ect their origins from gymnosperms and angiosperms, respectively.
CARBON ISOTOPES
CSIA
RESINS
RESINITES
HYDROCARBONS
OILS
AUSTRALIA
SE ASIA
Hydrocarbons derived from plant resins are major components of some terrigenous oils and bitumens. These compounds are structurally distinct and this makes them useful biomarkers applicable in petroleum exploration as well as sources of biogeochemical information about palaeoenvironment and palaeobotany. Although recent studies have elucidated the molecular structure of resinites, very lit- tle information has been available for the carbon isotope composition of resinites and no studies of resin-derived compounds in oils had been performed prior to the present study. Hence, carbon stable isotope analyses were carried out on a suite of modern and fossil resins of diverse origins, including compound speci®c isotope analysis of individual hydrocarbons produced during resin pyrolysis. Oils de- rived from resinitic source organic matter were also analysed. The results showed that ``Class I'' resi- nites derived from gymnosperms were enriched in the heavy carbon isotope compared with those from angiosperms (``Class II'' resinites). Furthermore, both fossil resinites themselves and individual hydro- carbons derived from them were isotopically heavy compared with modern plant resins. The isotopic signatures of diterpanes and triterpanes in various early Tertiary oils from Australasia and Southeast Asia re¯ect their origins from gymnosperms and angiosperms, respectively.
CARBON ISOTOPES
CSIA
RESINS
RESINITES
HYDROCARBONS
OILS
AUSTRALIA
SE ASIA