摘要
柴达木盆地西部第三系咸水湖相生油岩样品分析资料表明,不同沉积相带生油岩正构烷烃系列有三种碳数分布模式。深湖相生油岩在C18～C28范围呈明显的偶碳数优势,而>C28范围无碳数优势;滨浅湖相样品在整个碳数范围内呈奇碳数优势分布;过渡相带地层正构烷烃在中碳数范围呈偶碳数优势分布,而高碳数(>C23)部分为奇碳数优势分布。经不同沉积相带样品之间的沉积环境地球化学指标和碳酸盐含量比较发现,本区咸湖相生油岩正构烷烃的分布不取决于沉积环境的氧化还原性和岩石的矿物组成,而主要与沉积相带中的有机质生源组成有关。偶碳数优势分布的正构烷烃成因并非如常规观点解释的那样,由正构脂肪酸、醇类的还原作用或经碳酸盐催化发生β断裂而来,而可能来源于咸化湖泊中的某种嗜盐细菌或其他微生物。
The analytical data of source rock samples reveal three n alkane distribution patterns in Tertiary saline lacustrine strata deposited in different facies in western Qaidam Basin. The n alkanes with even carbon number preference in C18～ C28 range and no odd/even one in the range above C28 are found in the profundal lacustrine source rocks, the odd to even predominance in whole carbon number range in the marginal strata, and even over odd preference in middle carbon number range (C18～ C22) and odd over even one in the range above C23 in the transitional facies. Comparing the geochemical parameters for sedimentary environment and carbonate contents between source rocks deposited in various facies, the n alkane distribution patterns of the source rocks studied are believed to be independent of the redox in depositional environments and the mineral composition of source rocks, but to be associated with original organic matter composition within the given sedimentary facies. In opposition to the conventional proposition, the n alkanes with even carbon number preference could not be produced by the diagenetic reduction of corresponding n fatty acids and alcohols or by the mechanism in which carbonate catalyzes β breakage. It is possible that those n alkanes have been directly originated from philo salt bacteria or microorganism in saline lake.<P>
出处
《地球化学》
CAS
CSCD
北大核心
2003年第2期117-123,共7页
Geochimica
