A Biomarker Index for the Permian/Triassic Ecological Crisis

A unique biomarker - a C33 n-alkylcyclohexane ( n -heptacosylcyclohexane) - strongly increases in abundance within the extinction interval of the end-Permian ecological crisis, is reported from the key Permian-Triassic (P-Tr) marine section in Greenland (Grice et al., 2005b, Earth and Planetary Science Letters, 236, 315-321). Prior to this study, this compound had been known from Early Triassic organic-rich marine rocks and oils from the northern Perth Basin, Western Australia for two decades. We have identified the compound in high relative abundance in 29 samples from P/Tr marine sections from two separate paleogeographic localities, from Laurasia and Gondwana. Relative concentrations of the C33 n-alkylcyclohexane show similar changes to the relative abundances of extinct spinose acritarchs (Veryhachium and Micrhystridium) indicating that the source organism of the C 33 n-alkylcyclohexane is associated with the depositional environments/facies in which the acritarchs are indentified. These organisms probably formed the cornerstone of the unique marine ecosystem that thrived in the extinction aftermath in the Early Triassic Ocean.

Personnel

K. Grice, R. Twitchett, C.B. Foster, C. Looy, R. Alexander

Funding

ARC (QEII)

Collaborators

Plymouth University ( UK), Geoscience Australia ( Canberra), National Museum of Natural History ( Washington DC)