Origin of CO2 gas from the north depression of the middle fault zone in the Hailar-Tamtsag Basin and

Natural gas pools with the high contents of CO2 were discovered during exploring the middle fault zone of the Hailar-Tamtsag Basin.So far this kind of gas reservoir with CO2 with characteristics of carbon isotope is special.The stable carbon isotope of CO2 in the study area is relatively light with δ13 Cco2 values ranging from -13.1‰ to -8.2‰.The 40Ar/36Ar values of associated argon gas range from 916 to 996,with R/Ra of 1.20-1.26.Based on comprehensive analysis,it is believed that the CO2 gas in this study area is of crust mantle source.