Understanding the Permian-Triassic transition with fossil data before and after the mass extinction event

Environmental instability prior to end-Permian mass extinction reflected in biotic and facies changes on shallow carbonate platforms of the Nanpanjiang Basin (South China) 

Li Tian, Jinnan Tong, Yifan Xiao, Michael J. Benton, Huyue Song, Haijun Song, Lei Liang, Kui Wu, Daoliang Chu, Thomas J. Algeo

Summarized by: Baron C. Hoffmeister. Baron Hoffmeister is currently an undergraduate senior at the University of South Florida pursuing a degree in Environmental Science and Policy with a minor in Geology. After graduation, he plans to attend a graduate program for environmental management. When graduate school is complete, he plans on working for the National Parks services. Baron is apart of the geology club as well as the fishing club and spends his free time hiking, fishing, and socializing with friends.

What data were used? Fossil taxa found in Southern China carbonate platforms that date back to the Permian-Triassic extinction event, ~251 million years ago. This data sheds light on the mass extinction event that spans the Paleozoic and Mesozoic Eras. 

Methods: Analytical evaluation of fossils present from three separate stratigraphic areas across South China, from before, during, and after the Permo-Triassic extinction event. 

Results: In this study, the fossil data evaluated at each site led to the discovery of common trends. Each formation had similar fossil accumulations, even though the formation would have been located a far distance apart. This means that each location was affected similarly  by the same event for the accumulation of similar fossils to appear in the corresponding strata. This is hypothesized to be the late Permian mass extinction. Another similarity between the three areas was that each section had a foraminifera gap between strata boundaries. At the same time, each boundary represented a different aspect of a shallow marine environment. For example, the Wennga Formation had strata before the extinction boundary that was littered with Permian fauna fossils that occurred in shallow marine environments. Post-extinction boundary strata didn’t possess these fossils. This is another indication of the severity of the mass extinction event. The Taiping section had different types of rock formations with different compositions; the transition of the rock from before the extinction to after showed a rapid die-off of organisms living in this area. Finally, in the Lung Cam section, there were fewer fossils than the other two (most likely due to poor fossil preservation conditions); however, the fossils that were found resembled those in the other sections studied. Further, the Lung Cam section had foram gaps consistent with the other sections.

Skeletal composition within strata at each study section. The three sections had similar organisms preserved in each and even showed similar gaps in fossil occurrences, indicating where the extinction event happened.

Why is this study important? This study strengthens what we know about the Permian-Triassic transition. These fossils, across multiple areas, were present in a shallow marine environment and were greatly affected by environmental instability during this time. The strata at each location, Wengna, Taiping, and Lung Cam, are remnants from the fatal conditions in the marine environment at this time. This can better help us understand and conceive how shallow marine organisms could be affected today during climate change. 

The big picture: This study shows the significant changes in fossils from  before and after the largest extinction event in Earth’s history. There is consistent evidence within and between each section studied, indicating a widespread event that negatively affected shallow marine life during this time.

Citation: Tian, Li, Jinnan Tong, Yifan Xiao, Michael J. Benton, Huyue Song, Haijun Song, Lei Liang, Kui Wu, Daoliang Chu, and Thomas J. Algeo. “Environmental instability prior to end-Permian mass extinction reflected in biotic and facies changes on shallow carbonate platforms of the Nanpanjiang Basin (South China).” Palaeogeography, Palaeoclimatology, Palaeoecology 519 (2019): 23-36. DOI: 10.1016/j.palaeo.2018.05.011

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