[B-CG10] Phanerozoic biodiversity change: Extinction and diversification

[BCG10-P01] Polycyclic Aromatic Hydrocarbons during the Recovery from the end-Permian Mass Extinction in the Norwegian Sea

*Calum Peter Fox¹, Kliti Grice¹, Rolando di Primio² (1.WA-OIGC, Curtin University, 2.Lundin, Norway)

Keywords:Mass Extinction, Polycyclic Aromatic Hydrocarbons (PAHs), Permian-Triassic

Five mass extinction events are recorded in the geological past. Arguably the most catastrophic is the end-Permian Mass Extinction (EPE) that occurred ~252 million years ago. During this period major extinction occurred in the both the marine and terrestrial realms, with ~95% of marine life and ~70% of terrestrial vertebrates becoming extinct. Recovery of life is an important factor regarding mass extinction events, and due to the severity of the EPE it has been suggested that recovery took on the order of 10 million years. Biomarkers are molecular fossils of lipids that derive from the 3 domains of life. During mass extinction events they are able to provide insights into the changes of redox, environmental and ecological conditions. One such group of these biomarkers are the Polycyclic Aromatic Hydrocarbons (PAHs). PAHs are associated with hydrothermal activity, the incomplete combustion of fossil fuels and wood, and may be formed during sedimentary diagenesis and catagenesis. During the EPE, the appearance of PAHs associated with incomplete combustion are found in sections from Western Australia, Greenland, China, and Canada. Here, data is shown from the Panthalassa Ocean in the Northern Hemisphere during the recovery of the EPE showing an abundance of PAHs. These include benzo(a)pyrene, benzo(e)pyrene, coronene, fluoranthene and pyrene. The pattern of a uniform increase in each of these biomarkers indicates an emergence of wildfires during the EPE recovery phase. Perylene a fungal wood marker, is present in extremely low concentrations. Retene is one such PAH that can be produced by wood combustion, but has also been suggested as a source of phytoplankton in sediments from the geological past. As retene shows a similar pattern to other combustion elated PAHs it is likely tracking the combustion of wood and is thus an additional indicator of wildfire. Ratios of dibenzothiophene and phenanthrene are representative of the source rock lithology (values >1 are carbonates and values <1 are shales) and shows clear transition across the Permian-Triassic boundary.