Abstract: The carbon stable isotopic compositions and variations are examined for the Upper Cretaceous marine carbonate rocks in the Gamba region, and the stratigraphic correlation is made for the study area and other coeval marine strata in southern Xizang and Europe. The carbon stable isotopic records in the Gamba strata have well responsed to the global anoxic events during the Cretaceous. The lithostratigraphic and environmental analysis shows that the changes of oceanic dissolved oxygen contents caused by global sea-level changes and plate movement are a cause or effect of the deviation of δ¹³C values.