Identical carbon isotope trends of carbonate and organic carbon and their environmental significance from the Changhsingian (end-Permian), Meishan, South China.

High resolution carbon isotope analyses of carbonate and organic carbon from Meishan, South China showed that the variation of δC is marked by three large positive excursions during the Changhsingian (end-Permian). Carbon isotope stratigraphy during this stage shows three cyclic intervals in δC, with two cycles corresponding to the lower (Paleofusulinid minima Zone) and one corresponding to the upper Changhsingian (P. sinensis Zone). The large positive δC excursions indicate episodes of enhanced burial of isotopically light organic carbon, presumably in response to deep-water anoxia episodically extending into shallow water with the rise of sea level. The organic carbon during the Changhsingian is distinguished into two groups, and the δC of each group parallels (separately) the more detailed profile of δC, strongly showing that the values of fractionation ΔC remain relatively constant, with only two intervals with anomaly. The enhanced fractionation ΔC with large negative δC excursions apparently indicates significant inputs from sulfide-oxidizing bacteria and green sulfur bacteria, notably at bed 24 just predating mass extinction. Our evidence appears to support that the extended euxinic water is possible for the main pulse of mass extinction at the end-Permian. [ABSTRACT FROM AUTHOR]