Fig. 4From: Authigenic carbonate precipitation at the end-Guadalupian (Middle Permian) in China: Implications for the carbon cycle in ancient anoxic oceansChemostratigraphic profile of the δ13Ccarb values of the authigenic carbonates at Chaotian. The δ13Ccarb values of the bioclastic limestone and black calcareous mudstone (open circles) were reported in Saitoh et al. (2013b). Except for some samples with lower values, the δ13Ccarb values of the carbonates are similar to or slightly lower than those of the black mudstone. U.P. upper partBack to article page