摘要
Carbon dioxide gas pools occur widely in the basins of eastern China.CO_2 gas-bearing beds are from the Teritary to Ordovician,and reservoirs are sandstone,carbonates and volcanics.The gases from these gas pools contain CO_2 of 62.86 ‰ —99.55 ‰.In the Mesozoic-Cenozoic extensional basins,such as Songliao,Bohai Bay,Subei,Sanshui and Zhujingkou,the δ^(13)C_(CO_2)values of CO_2 gas pools range from-2.65‰ to-8.83‰,mainly from-3.5‰ to-6.0‰,~3He/~4He ratios are 2.65R_a to 4.96R_a.The regression equa- tion of CO_2 content and helium isotope ratio is CO_2(%)=61.3852+7.9745R/R_a,correlation coefficient r is 0.9430,CO_2 is mainly mantle-derived and magmatic origin.δ^(13)C_(CO_2)value of CO_2 gas from Well X in Yinggehai Basin is-3.80‰.~3He/~4He ratio is 0.07R_a,CO_2 is metamorphic origin.Mantle-derived and magmatic CO_2 gases are discharged from the cross areas of northeastern trending and northwestern trending faults in these Mesozoic-Cenozoic extensional basins,in the shallow level,the CO_2 gases migrate and accumulate along northeastern trending extensional faults.The activity of the Neogene to Quaternary northwestern trending tectonic-magmatism zones in eastern China is another important discharge event for mantle-derived and magmatic gases,which have great contribution to the CO_2 gas pools in this area.Metamorphic CO_2 in the Yinggehai Basin is released by the dynamic metamorphism of shear fractures.
Carbon dioxide gas pools occur widely in the basins of eastern China.CO<sub>2</sub> gas-bearing bedsare from the Teritary to Ordovician,and reservoirs are sandstone,carbonates and volcanics.The gases fromthese gas pools contain CO<sub>2</sub> of 62.86 ‰—99.55 ‰.In the Mesozoic-Cenozoic extensional basins,such asSongliao,Bohai Bay,Subei,Sanshui and Zhujingkou,the δ<sup>13</sup>C<sub>CO<sub>2</sub></sub>values of CO<sub>2</sub> gas pools range from-2.65‰to-8.83‰,mainly from-3.5‰ to-6.0‰,<sup>3</sup>He/<sup>4</sup>He ratios are 2.65R<sub>a</sub> to 4.96R<sub>a</sub>.The regression equa-tion of CO<sub>2</sub> content and helium isotope ratio is CO<sub>2</sub>（%）=61.3852+7.9745R/R<sub>a</sub>,correlation coefficient r is0.9430,CO<sub>2</sub> is mainly mantle-derived and magmatic origin.δ<sup>13</sup>C<sub>CO<sub>2</sub></sub>value of CO<sub>2</sub> gas from Well X inYinggehai Basin is-3.80‰.<sup>3</sup>He/<sup>4</sup>He ratio is 0.07R<sub>a</sub>,CO<sub>2</sub> is metamorphic origin.Mantle-derived and magmaticCO<sub>2</sub> gases are discharged from the cross areas of northeastern trending and northwestern trending faults inthese Mesozoic-Cenozoic extensional basins,in the shallow level,the CO<sub>2</sub> gases migrate and accumulate alongnortheastern trending extensional faults.The activity of the Neogene to Quaternary northwestern trendingtectonic-magmatism zones in eastern China is another important discharge event for mantle-derived andmagmatic gases,which have great contribution to the CO<sub>2</sub> gas pools in this area.Metamorphic CO<sub>2</sub> in theYinggehai Basin is released by the dynamic metamorphism of shear fractures.
基金
the National Natural Scienoe Foundation of China
