This paper investigates kerogen carbon isotopes, the difference between carbonate and kerogen carbon isotopes (D 13 C carb-kero = d 13 C carb -d 13 C kero ) and the difference between carbonate and n-C 19 alkane compound-specific carbon isotopes (D 13 C carb-n-C19 = d 13 C carb -d 13 C n-C19 ) during the Permian-Triassic transition at Meishan, South China. The results show that kerogen carbon isotopes underwent both gradual and sharp shifts in beds 23-25 and 26-29, respectively. The differences between carbonate and organic carbon isotopes, both the D 13 C carb-kero and D 13 C carb-n-C19 , which are mainly affected by CO 2 -fixing enzyme and pCO 2 , oscillated frequently during the Permian-Triassic transition. Both the variations of D 13 C carb-n-C19 and D 13 C carb-kero coupled with the alternation between cyanobacteria and green sulfur bacteria indicated by biomarkers. The episodic low values of D 13 C carb-n-C19 corresponded to episodic blooms of green sulfur bacteria, while the episodic high values of D 13 C carb-n-C19 corresponded to episodic blooms of cyanobacteria. The relationships between the variation of carbon isotopes and biota show that the microbes which flourished after the extinction of macroorganism affected the carbon isotope fractionation greatly. Combining the carbon isotope compositions and the pattern of size variation of the conodont Neogondolella, this paper supposes that anoxia of the photic zone at bed 24 was episodic and it would be caused by the degradation of terrigenous organic matters by sulfate reducing bacteria in the upper water column. Considered together with results from previous research, the high resolution variation of the biogeochemistry presents the sequence of the important geo-events during the PermianTriassic crisis.
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