Abstract:

In order to understand the genesis of carbon dioxide gas in the Shangdou region for the guidance of carbon dioxide gas exploration, by means of the carbon dioxide gas geochemical analysis such as gas component，carbon isotope，helium isotope and hydrogen isotope, the characteristics are the carbon dioxide concentration is 97.23%-97.85%,the value of the carbon isotope δ¹³C is -6.5‰--5.2‰,the value of the associated gas He isotope ³He/⁴He is （1.69-3.35）×10^-6,the value of H₂ isotope δD(H₂) is -760‰--860‰ and the calculated the share of mantlederived helium is 69.7%-84.8％,which showed that the genesis of carbon dioxide gas is abiogenic obviously. Meanwhile，geological features of the deep faults development,the geological background of the strong magmatic activity and the carbon dioxide in the inclusions of the Hannuoba basalt group indicated that the geological conditions and geological processes that the generation and migration-accumulation of mantlederived carbon dioxide exists and the genesis of carbon dioxide gas in the Shangdou region is abiogenic undoubtedly. Geological conditions and previous exploration results indicate the good prospects for carbon dioxide gas exploration in the region.

Key words: Inner Mogolia, Shangdou region, carbon dioxide, mantle-derived origin