生物标志物组合与苏北金湖凹陷阜二段(Ef_2)沉积环境研究

Biomarker Assemblage and Study on Sedimentary Environments of Member 2 of Funing Formation, Lower Tertiary, Jinhu Sag, Subei Basin

阜二段生油岩可以分为两类:一类以具有正构完烃的偶碳优势为特征,伴随有强烈的植烷优势,以及高丰度的β-胡萝卜烷、伽玛蜡烷和脱羟基维生素E,显示出强还原条件下半咸水介质的沉积特征;另一类则具有正构烷烃奇碳优势,植烷优势不明显,且β-胡萝卜烷和伽玛蜡烷含量很低,未检测出脱羟基维生素E系列的标志物,属于水体还原程度和(或)含盐度较低条件下的一种产物。

The features of bipmarker assemblage in the saturate and aromatic fractions of source rocks from Member 2 of Funing formation, Lower Tertiary, Jinhu, Subei Basin have been systematically studied, and the obvious differences in biomarker components are indicated which would clearly show the changes of sedimentary environments during their deposition. Based on n-alkane distribution and biomarker assemblage, source rocks from Member 2 of Funing Formation may be devided into two types: One is characteristic of even carbon predominance in n-alkane distribution with a very sttong phytane preference. The content of β-carotane preserved and formed under reducing conditions is high, gammacerane usually indicating a hypersaline environment is enriched, and dehydroxytocopherol, rellection the paleaosalinity of sedimentary basin has been identified in the aromatic fraction sf the same source rocks, all of them show that these source rocks may be reffered to a strong reduced, brackish deposit, implying a salinized period during the lake lifetime. Another is of odd carbon predominance in n-alkane distribution, its phytane preference relatively less. the abundances of β-carotane and gammacerane is much lower, and dehydroxytopcopherol is not detected. Therefore, it is characterised by normal lacustrine deposits and formed during a freshening period.