Geological and Geochemical Characteristics of Source Rocks of Carbon Dioxide in Deep Strata of Northern Songliao Basin, Northeast China

Based on studies of major element, rare earth element, fluid inclusion and absorbed gas, the possible source matters of carbon dioxide (CO2) and their potentialities to form gas accumulations in deep northern Songliao basin, NE China were addressed in this paper Mantle-derived magma, volcanic rocks, carbonate rocks and organic matters are four kinds of potential source matters, whose significances are degressive in turn and vertical distributions could be divided into shallow, middle, deep and deeper levels In shallow level, the source matters of CO2 are volcanic rocks and carbonation rocks with higher total carbon contents and absorbed CO2 contents, 0 24%-7 76% and 0 213%-1 387% respectively The absorbed CO2 contents of volcanic rocks are negatively correlated with the SiO2 contents, and positively with the Na2O+K2O contents The principal source matters are metamorphic carbonate rocks in middle level and mantle-derived magma in deep and deeper levels Higher CO2 abundance in magmatic systems corresponding to deep volcanic rocks could be suggested by characteristics of lithogeochemistry and fluid inclusion as well as tectonic setting The volcanic rocks of Yingcheng Formation and corresponding magmatic activities are the most favorable CO2 source matters in northern Songliao Basin