沟鞭藻：24-降胆甾烷的重要生源

DINOFLAGELLATES AS POTENTIAL PRECURSORS OF 24-NORCHOLESTANES

王广利 李姝

Wang Guangli Li Shu

油气资源与探测国家重点实验室(中国石油大学), 北京, 102249 2. 中国石油大学 资源与信息学院, 北京, 102249 3. 中国石油化工股份有限公司, 石油勘探开发研究院, 北京, 100083

State Key Laboratory of Petroleum Resources and Prospecting, China University of Petroleum, Beijing 102249, China 2. School of Natural Resources and Information Technology, China University of Petroleum, Beijing 102249, China 3. Research Institute of Petroleum Exploration and Production, SINOPEC, Beijing 100083, China

24-降胆甾烷是出现在原油和沉积有机质中的一类重要分子化石,其在地层中的分布与地质时代、古气候和沉积相等有关。国内外研究表明,硅藻是24-降胆甾烷的重要生源。通过研究发现,在缺少硅藻化石的渤海湾盆地济阳坳陷古近系沙河街组湖相沉积中,发育丰富的24-降胆甾烷,且与地层中的沟鞭藻分子化石(三芳甲藻甾烷)和生物化石(囊孢)存在明显相关性。因此可以推测,沟鞭藻是24-降胆甾烷的另一重要生源。由于沟鞭藻和硅藻分布的差异,不同盆地中24-降胆甾烷的来源存在区别。济阳坳陷古近纪气候温暖湿润,沟鞭藻极度繁盛,是24-降胆甾烷的主要贡献者。

Occurring widely in oils and ancient sediments,24-norcholestanes are useful to oil-source correlation and petroleum age evaluation.24-norcholestanes mainly derive from diatoms;however,they are also identified unambiguously from dinoflagellates.Abundant 24-norcholestanes occur in oils and source rocks of the Shahejie Formation,but no diatom fossils have been distinguished from the Shahejie Formation.Thus,other potential precursors might be responsible for these 24-norcholestanes.A correlative relationship between 24-norcholestanes and dinocysts or triaromatic dinosteroids has been observed,revealing that dinoflagellates should be potential precursors of 24-norcholestanes.It seems that 24-norcholestanes come from dinoflagellates and diatoms,respectively,for different basins.Notwithstanding the fact that 24-norsterols have low concentrations in contemporary dinoflagella test,it is concluded that dinoflagellates are key contributors to 24-norcholestanes within subtropical lacustrine sediments of the Eocene-Oligocene Jiyang Depression.

国家自然科学基金项目(40703011)

https://doi.org/10.11781/sysydz201001064