Source apportionment of PAH at the Triassic-Jurassic boundary with implications for the link between volcanism and floral change
Final Report Abstract
The leading “suspect” for the Triassic-Jurassic (T/J) boundary mass-extinction event, which occurred 200 million years ago, is the eruption of the Central Atlantic Magmatic Province (CAMP), causing the release of large quantities of CO2 and SO2 to the atmosphere. In response, the T/J boundary marks a dramatic change in land plants from forests dominated by conifers, seed ferns and cycads to a pioneering, low-growing vegetation that was entirely composed of primitive ferns and fern allies. Samples from the T/J boundary also contain elevated levels of highly toxic polycyclic aromatic hydrocarbons (PAH). The PAH are thought to have formed when ascending lava from the Central Atlantic Magmatic Province interacted with surrounding sediments, such as coal beds, heating them up, and thereby releasing large quantities of additional carbon, sulfur, and other toxic compounds into the atmosphere. Detailed organic geochemical and palynological investigations were undertaken on the newly drilled Schandelah core from northern Germany with the aim to reproduce a low-resolution study of the Mariental core (N Germany). The palynological data serves to establish a firm biostratigraphic framework, as well as to document supraregional changes in vegetation. Boundary beds at Schandelah also record a peculiar signal of large amounts of reworked Palaeozoic acritarchs, indicating intense weathering and erosion. These changes co-occur with elevated levels of PAH, which are evident from a new high-resolution data set obtained from the Schandelah core. Combined, the data provide evidence for a scenario in which volcanic activity triggered deforestation and strong weathering. A further aim of the project was to trace PAH back to one of their potential sources, namely Carnian coal beds that were intruded by CAMP dikes and sills. These naturally occurring cokes, exposed in a number of old open mine pits in North Carolina, were sampled in May 2013. Organic geochemical work on those samples is ongoing.
Publications
- (in review). Volcanic CO2 did not cause the late-Triassic biodiversity crisis in Europe. Nature Geoscience
Jeram, A.J., Hesselbo, S.P., van de Schootbrugge, B., Manick, K., Wignall, P.B., Simms, M.J.
- 55th Palaeontological Association Annual Meeting, Plymouth (UK) - Microbes, Mud & Methane: Recurrent Early Jurassic anoxia following the end-Triassic mass-extinction
Bas van de Schootbrugge
- (2012). Hydrogen sulphide poisoning of shallow seas due to end-Triassic global warming. Nature Geoscience, 5, 662-666
Richoz, S., van de Schootbrugge, B., Pross, J., Püttmann, W., Quan, T.M., Lindström, S., Heunisch, C., Fiebig, J., Maquil, R., Schouten, S., Hauzenberger, C., Wignall, P.B.
- (2012). No causal link between terrestrial ecosystem change and methane release during the end-Triassic mass-extinction. Geology, 40, 531-534
Lindström, S., van de Schootbrugge, B., Dybkjaer, K., Pedersen, G.K., Fiebig, J., Richoz, S.
(See online at https://doi.org/10.1130/G32928.1) - Source Apportionment and Significance of PAH Associated with the Triassic-Jurassic Boundary Mass-extinction Event, ISPAC 23, Münster, Germany
Bas van de Schootbrugge, Wilhelm Püttmann, Sofie Lindström, Jörg Pross
- (2013). Microbes, mud, and methane: Cause and consequence of recurrent Early Jurassic anoxia following the end-Triassic mass-extinction. Palaeontology, 56, 685-709
van de Schootbrugge, B., Bachan, A., Suan, G., Richoz, S., Payne, J.L.
