Carbon isotope of kerogen was heavier in deep formations of the Songliao Basin, but lighter carbon isotope may generate because the enrichment of 12 C in fatty side chains.

• 松辽盆地深层泥质烃源岩干酪根碳同位素比较重,但由于其脂肪支链上富集12C,因此生成的烃类碳同位素却比较轻。