Lithology and diagenesis are important components in δ13Ccarb stratigraphic variation in Lower Cambrian Forteau Formation limestones. The δ13C values of ooids indicate that shallow seawater ΣCO2 was -1.0‰ to 0.0‰. Salterella and archaeocyathans probably exerted a vital effect on the carbon isotopic composition of their skeletal CaCO3. The diversification of early skeletal organisms complicated the biogeochemical cycling of carbon isotopes during the Precambrian-Cambrian transition, making δ13C chemostratigraphy and isotopic mass-balance calculations more difficult in Lower Cambrian and younger deposits. Similar studies should be carried out on other Lower Cambrian sections before the carbon isotopic chemostratigraphic technique can be validated for this important interval.