Abstract: Taking the Chongqing Nanchuan-Wulong bauxite as the research object,26 samples containing bauxite,clay rock,limestone,silty shale were selected to investigate the environment of ore-bearing rock forming and the source of ore-forming materials by analyzing the distribution of carbon and oxygen isotopes.According to the distribution range of δ¹³C_V-PDB,δ¹⁸O_V-PDB and δ¹⁸O_V-SMOW,C mainly came form carbonate rocks,the salinity of water medium in the process of rock-forming (ore-forming) varies greatly,but fresh water was the main part of the water medium.In addition,the forming process of ore-bearing rock series may be accompanied by the ancient landform changes,and seawater intrusion was possibly the factor.According to the feature of C,O isotope,it inferred that the source of ore-forming materials owns the feature of diversity,among which shale and limestone were regarded as the source of material.Combining with the characteristics of zircon and the field observations,silurian shale was the main source of ore-forming material.In general,the Nanchuan-Wulong bauxite was formed under a hot and humid climate,and a relatively closed,water retained and reducing environment.

Key words: Bauxite, Isotope, Ore-forming environment, Material source, Nanchuan-Wulong