盐湖相生油岩中某些地球化学参数与沉积环境的关系

The relationship between some geochemistry parameters and environment in saline facies

柴达木盆地西部第三系盐湖相沉积生油岩中，含有丰富的碳酸盐岩，局部层段还含有盐岩、石膏和芒硝。生油岩中生物标志化合物的组成和分布与沉积环境有着密切的关系。沉积环境中盐度的增加可以抑制Ｔｍ向Ｔｓ的转化，反映母源输入的参数甾烷Ｃ２７／Ｃ２８十Ｃ２９比值，随岩石中Ｃｌ－离子含量的增加而增大。成熟度参数藿烷Ｃ３１Ｓ／Ｒ及甾烷Ｃ２９ββ／αα＋ββ比值随岩石中碳酸盐含量的增加而减小，表明碳酸盐对甾烷和藿烷的差向异构化反应存在着迟缓效应。

Abstract The Tertiary are saline sediment in western part of Qaidam Basin. The source rocks of oil contain much of carbonate and some strata even contain halite and mirabilite. The concentration of chlorine is higher in rocks. The composition and distribution of biomarkers have a close relationship with their sedimentary environment. The increasing of salinity in sedimentry environment can restrain the transformation from Tin to Ts. In addition, the formation of Ts may relative to some aquatic organism in saline factes. Sterane Parameter of C27/C28+C29 ratios which can reperesent the input information of organism have a positive relationship with the concentration of Cl-Show that because of dry climate, the supplying of higher plants decrence, the salinity incrence in water and some aquatic organism which can living in saline water may incrence. Many publications have shown that the hopane parameter of C31 S/R ratio and the sterane parameter of C29 ββ/αα+ββ ratio both can reflect the maturity degree of source rocks and oils. But in Qaidam Basin, when the concentrations of carbonate is lower than 25%, both of the C31S/R ration and the C29 ββ/αα+ββration have a pesitive relationship with the concentrations of carbonate, when the concentrations of carbonate is higher than 25%, both of the parameters have a negative relationship with the concentrations of carbonate. Show that the higher amount of carbonate have a restricted effection on the isomerisation of sterane and hopane.