柴达木盆地察尔汗湖区古湖相沉积物中含氮类分子化石的检出

The Distribution of Nitrogen-bearing Lipid Biomarker in the Shell Bar Paleolake Sediments from Qarhan Paleolake,Qaidam Basin

利用气相色谱质谱联用仪(GC-MS)对青藏高原柴达木盆地察尔汗湖区贝壳堤剖面古湖相沉积物样品进行了系统地分析,检测出系列脂肪酸酰胺与脂肪腈类含氮类脂物分子化石。并对其在古湖相沉积物中的分布特征作了详细描述。对它们综合研究认为,早期成岩作用使来源于各种生物体的脂肪酸酰胺类分子化石部分地转化为脂肪腈类化合物。此外,不饱和脂肪酸酰胺与饱和脂肪酸酰胺的含量比值在剖面上并没有呈现明显下降的趋势,说明在降解过程中各种生物、物理及化学作用对它们不存在明显的选择性,指示有机质在沉积过程中可能处于一个偏氧化的环境。本文首次报道这两类物质,为更好地理解含氮类脂物分子化石在湖泊沉积物中的转化过程提供了一定的理论依据。

A series of analogs of fatty acid amide and fatty nitrile were identified along the shell bar section of the Qaidam Basin in Qinghai-Tibet Plateau by using the gas chromatography-mass spectrometry（GC-MS）.On such a basis,the distribution characteristics of the nitrogen-bearing lipids have been discussed in detail in this paper.According to previous studies and geographical conditions of the Qaidam Basin,the authors hold that the early diagenesis partly converted the fatty acid amide into the fatty nitrile.However,the ratio of the unsaturated fatty acid amide to the saturated one is relatively stable in the profile,indicating that there existed no obvious selectivity between these two types of fatty acid amides during the diagenetic processes including various biological,chemical and physical actions.It is therefore concluded that the depositional environment in the Qarhan paleolake was relatively aerobic during the organic component deposition.Being the first description of the fatty acid amide and fatty nitrile in paleolake sediments,this report provides the basis for the nitrogen-bearing lipids investigation in lake sediments.