【摘要】 济阳坳陷古近纪沟鞭藻化石十分丰富,沟鞭藻为有机质富集层的形成作出了重要贡献。三芳甲藻甾烷和甲藻甾烷是沟鞭藻及其祖先在古代沉积物中两种重要的存在形式,并且它们几乎专一性地由沟鞭藻提供。研究发现,沟鞭藻的不同属种,德弗兰藻属、多刺甲藻属、渤海藻类等,均可以提供丰富的三芳甲藻甾烷和甲藻甾烷,但是三芳甲藻甾烷和甲藻甾烷对沉积环境的变化具有不同的响应。在淡水、半咸水、咸水等不同水介质条件下,三芳甲藻甾烷指数稳定分布在0.50～0.96之间,高丰度的三芳甲藻甾烷与地层中丰富的沟鞭藻化石相一致,因而三芳甲藻甾烷是指示沟鞭藻输入的有效分子化石。甲藻甾烷的丰度与古沉积环境存在密切关系,高盐环境有利于甲藻甾烷的形成和保存,随着盐度的降低甲藻甾烷指数在0.04～0.74这样一个较大的范围内变化,其发育程度与有机质沉降过程中和成岩作用早期遭受的微生物降解作用有关,强烈的生物降解不利于甲藻甾烷的保存。更多还原

【Abstract】 Triaromatic dinosteroid hydrocarbons and dinosteranes are two important molecular fossils derived from dinosterols,compounds known in modern organisms to be the nearly exclusive widely occurring natural products of dinoflagellates.Now they have been identified from a Paleogene lacustrine basin,Jiyang super-depression located at East China,by GC-MS and GC-MS-MS.The results show that different genera of dinoflagellates including the Deflandrea living in saline-brackish lacustrine(Es4u),the Sentusidinium-Rhombodella in brackish lacustrine(Es1) and the Bohaidina-Parabohaidina in fresh lacustrine(Es3) all could offer these two molecular fossils.However,it is observed that there are not linear pertinences between the triaromatic dinosteroid hydrocarbons and dinosteranes.The abundance of triaromatic dinosteroid hydrocarbons is consisted with the distribution of dinocysts in the Shahejie Formation.In saline and near-shore deposition,the TAI(triaromatic dinosteroid index) is 0.1～0.43,indicating a low production of dinoflagellates;in sub-deep to deep lacustrine whatever brackish or fresh the TAI is 0.50~0.96,suggesting a high production of dinoflagellates.But the abundance of dinosteranes is corresponding to the changing depositional environments;high palaeosalinity or low biodegradation during organic matter subsiding and early stage of diagenesis is in favor of the preservation of dinosteranes.更多还原