近代盐湖沉积物中的生物标志化合物  

BIOMARKERS FROM RECENT SALT-LAKE SEDIMENTS

作　　者：范璞[1] 张柏生[1] 于心科[1] 

机构地区：[1]中国科学院兰州地质研究所

出　　处：《地球科学进展》1994年第3期6-17,共12页Advances in Earth Science

摘　　要：生物标志化合物是在沉积有机质地质演化过程中可保留其原碳骨架的生物分子，具记录沉积环境和沉积有机质热演化历史的功能。用有机地球化学方法（气相色谱、气相色谱／质谱、热解色谱和同位素质谱）对采自我国西部盐湖的近代沉积物进行了大量研究，而且对盐湖沉积环境地球化学特征、有机质组成与早期成岩作用的关系和各种生物标志化合物指标进行了更加深入细致的探索。研究结果表明干酪根碳同位素组成（δ￣（１３）ＣＰＤＢ）和盐湖类型有关系，例如，硫酸盐型湖的干酪根δ￣（１３）Ｃ值较重，而碳酸盐型盐湖的δ￣（１３）Ｃ值则较轻。姥鲛烷／植烷比（Ｐｒ／Ｐｈ）、总三环萜烷／总萜烷（％）、孕甾烷／甾烷比（％）、伽玛蜡烷／αβ—藿烷和三芴系列化合物组成三角图等生物标志化合物指标可以用来判识沉积环境的盐度。通常，在盐湖或咸水沉积环境中，除额吉卓尔盐湖样品因采自边缘，Ｐｒ／Ｐｈ比值较大而外，其余各盐湖样品的Ｐｒ／Ｐｈ比值一般≤１．０，而其余各比值均明显大于在淡水湖中的比值；三芴系列化合物三角图中，各盐湖样品均集中分布在硫芴含量高的区域。与我国各典型沉积环境中的原油及古代岩样的分析结果作了对比，发现同样表现出上述规律，故认为是良好的识别标志。正构烷烃分布、?Organic matter and biomarkers from many recent salt-lake sediments in West Chinahave been investigated in the present paper by gas chromatography(GC),gas chromatog-raphy mass spectrometry(GC/MS)multiple ion detection,pyrolysis and isotope massspectrometry.Particular emphasis has been placed on the geochemical characteristics of thesaline sedimentary environment,the nature of organic matter and the early diagenesis onthe basis of the general geochemistry characteristics of organic matter and compositions,distributions and molecular parameters of various biomarkers. The results show that thecarbon isotope composition(λ￣(13)C)in kerogen seems to have a certain relationship with thesalt-type of salt lakes;pristane/phytane(Pr/Ph)ratio,∑tricyclic terpanes/∑terpanes(%),∑pregnanes/∑steranes(%),gammacerane/αβ-hopane and the relative percentage of threefluorene series compounds could be regarded as good indicators recognizing sedimentaryenvironments of different salinities; the distribution of n─alkanes,the relative concentra-tion of C_(27) ,C_(28) and C_(29) steranes and the occurence of some typical biomarkers such as tri-cyclic diterpane can be used to determine the nature of organic matter.Additionally,we re-port here on m/z 217,m/z 231,m/z 245 and m/z 259 tri-aromatic steranes found in recentsediments from each salt lake and infer their possible origin.

关 键 词：盐湖 沉积物 生物标志 化合物 

分 类 号：P512.3[天文地球—地质学]