Changes in Abundances and Stable Carbon Isotopes of Biomarkers Across the Permian-Triassic Schuchert Dal section (Eastern Greenland)

Biomarker and isotope analysis of the Schuchert Dal P/Tr section, Eastern Greenland have been used to reconstruct environmental changes before and during the extinction. Biomarker distributions were used together with palynology data from previous studies to show a series of changes in the terrestrial plant species throughout the sedimentary record. The pre-extinction period was dominated by dibenzofuran, dibenzothiophene and biphenyl. Based on the redox conditions and the availability of sulfur these compounds have been assigned to lignin from woody plants. The beginning of the extinction period was dominated by the biomarkers retene and cadalene, attributed to a high abundance of herbaceous lycopsids. After the decline of herbaceous plants, gymnosperm shrublands became the most prolific plants, characterized by high amounts of plant waxes. 13C/12C of biomarkers, carbonates and TOC and sulphur isotopes of iron sulfides support a major reorganization of the global carbon and sulfur cycles. 13C/12C of plant waxes and carbonate suggest that CO2 in the atmosphere and ocean was isotopically light shortly after the extinction, supporting the theory of methane release from melting gas hydrates. These isotopic excursions occur after the beginning of the extinction indicating they can not the primary cause and support the theory that several mechanisms may have been involved. Some of the environmental changes have also been observed in other P/Tr sections from Italy and Western Australia, supporting a global process.

Personnel

K. Grice, R. Twitchett, M. Boettcher, S Fenton

Funding

ARC (QEII)

Collaborators

Max Planck Institute for Marine Microbiology ( Germany) , Plymouth University ( UK)