中文摘要：

应用生物标志物分析技术,结合其他地球化学资料,对西藏羊湖盆地新生代雅西措群烃源岩的有机质生源构成、沉积环境和成熟度进行了讨论,结果显示：烃类有机组分包括正构烷烃、萜类、甾类和类异戊二烯烃等。分析图谱结果显示正构烷烃主峰为C23、C27、C29及C31,碳数分布范围很宽;OEP的平均值为4.56,Pr/Ph的平均值为0.24,植烷有明显优势。规则甾烷呈不对称的＂V＂字形分布,其C27/C29比值介于0.18～1.41之间。生物标志物特征指示了烃源岩中的有机物来源于菌藻类和高等植物输入,显示了较高盐度的还原性湖相沉积环境。甾烷成熟度参数C29ααα20S/ααα（20S＋20R）值为0.046～0.382,C29αββ/（ααα＋αββ）值为0.203～0.399,萜烷成熟度参数C3122S/（22S＋22R）值约为0.415,结合其他指标综合判断,有机质演化主体处于低成熟-成熟阶段。

英文摘要：

The biologic-source constitution,sedimentary environment and maturity of organic matter in the Cenozoic hydrocarbon source rocks in Yaxicuo Group are researched by means of biomarker analysis technology combined with other geochemical data.The results show that the hydrocarbons fractions contain n-alkanes,terpanes,steranes and isoprenoids.The distribution of n-alkanes exhibits the highest peak of nC23,nC27,nC29 and C31,and n-alkanes distribution pattern has a wide range of carbon atom numbers.The average value of OEP is 4.56 and that of Pr/Ph ratio is 0.24,indicating the dominance of phytane.The sterane content shows an asymmetrical ＂V＂ shape,and that C27/C29 ratio changes between 0.18 and 1.41.The biomarkers characteristics indicate that the main sources of the organic matters are algaes and bacteria and higher plants.Some of the biomarkers indicate that the sedimentary environment is characterized by the reduced lake conditions and high salinity.The value of C29ααα20S/ααα（20S＋20R） of steranes is 0.046~0.382,that of C29 αββ/（ααα＋αββ） is 0.203~0.399,and C3122S/（22S＋22R） of terpanes is 0.415.And integrated with other proxies of maturity,it is concluded that the organic matter of the source rocks is mainly in a low maturity-maturity stage.