T80 Global Change: Evolution and Extinctions in the Triassic

Monday, 5 November 2018
8:00 AM - 12:00 PM
Room 136-137

THE CORRELATION OF THE PERMIAN–TRIASSIC TRANSITIONAL BEDS AND MASS EXTINCTION IN CONTINENTAL-MARINE SILICICLASTIC SETTINGS OF WESTERN GUIZHOU AND EASTERN YUNNAN, SOUTHWESTERN CHINA

Paper number: T80-3
Program: Technical Sessions
Time: 8:35 AM – 8:55 AM

Authors

Abstract

The Permian-Triassic (P-Tr) boundary marks the greatest mass extinction during the Phanerozoic, which was coupled with major global environmental changes. However, the placement of the P-Tr boundary in terrestrial sections and accurate correlation with the marine strata are difficult due to the absence of the key index fossils in continental-marine siliciclastic settings. Here, we present detailed fossil data from the P-Tr boundary sections in western Guizhou and eastern Yunnan (WGEY), southwestern China. Our data show that the rapid mass disappearance of the Gigantopteris flora in various sections represents the end-Permian mass extinction and the base of the P-Tr transitional beds in continental-marine siliciclastic settings of South China. In particular, we find a mixed marine and terrestrial biota from the coastal transitional sections of the P-Tr transitional Kayitou Formation, which provides a unique intermediate link for biostratigraphic correlation between continental and marine sequences. In addition, evidence from paleobotany, organic carbon isotopes and charcoal from two non-marine P-Tr sections show a six-fold increase in the abundance of fossil charcoal coinciding with the onset of the negative carbon isotope excursion (CIE) and the catastrophic loss of tropical rainforest vegetation. Our data indicate that recurrent severe wildfires occurred at the same stratigraphic level as the onset of the CIE, suggesting a plausible cause for the mass extinction of the tropical rainforest. Based on comparison with modern El Niño events in equatorial Southeast Asia, we estimate that carbon emissions from tropical peatland wildfires during the onset of the P-Tr crisis, which is far from sufficient to drive the observed negative CIE. We assume that the synchronization of the onset of the CIE and recurrent severe peatland wildfires were potentially driven by volcanism.

Geological Society of America Abstracts with Programs. Vol. 50, No. 6

doi: 10.1130/abs/2018AM-318745

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