This work was supported by the National Natural Science Foundation of China (Grant Nos. 49973008, 40172015) ; the Chinese Academy of Sciences (Grant No. KZCX2-116).
Along the Proterozoic stratigraphic sections of Jixian, Tianjin, the ??13C values of carbonates are mostly negative in the Changchengian (Changcheng System), varying approximately within a range of (0±1)‰ in the Jix...