Fig. 9
Average variation trends of chemical weathering, land surface temperature and palaeoclimate across the Shahai and Fuxin formations, which can be divided vertically into stages A, B, C and D. Green shading represents the location of OAE1b. Chemical weathering trend (orange line) was indicated by chemical weathering indices CIAcorr., WIP and MIA(O) of mudstones from the Shahai and Fuxin formations. Land surface temperature (red line) was calculated by the linear relationship of CIA-temperature provided by Yang et al. (2014). The change trend of palaeoclimate (green line) inferred from palynological data is from Wan et al. (2017). I, II, III and IV represent the first, second, third and fourth members of the Shahai Formation, respectively