柴达木盆地第四系生物气气源岩中脂肪酮的检出及其成因探讨

从柴达木盆地第四系生物气气源岩一个剖面样品中检出了系列的脂肪酮-2、脂肪酮-3和脂肪酮-4,并对其进行了质谱鉴定和计算了不同碳数的脂肪酮-2在质量色谱图中的相对百分含量后发现:同一样品中脂肪酮-2、脂肪酮-3和脂肪酮-4的奇偶优势和碳数分布具有相似特征;在整个剖面上脂肪酮-2碳数分布变化较大,脂肪酮-2的奇偶优势在1.20~1.80之间,L/H比值在0.31~1.61之间。根据脂肪酮的分布特征及生标指数特征,结合地质背景,探讨了其成因,认为脂肪酮-2来源于柴达木盆地咸水-半咸水湖相生物或者气源岩内正构烷烃的生物氧化。

IDENTIFICATION OF ALIPHATIC KETONES IN BIOGENEIC GAS SOURCE ROCK IN QUATERNARY OF QAIDAM BASIN AND APPROACH TO THEIR SOURCES

A series of alkan-2-ones,alkan-3-ones and alkan-4-ones were found and identificated with mass spectra in a vertical profiles of biogenic gas source rocks in the Quaternary of the Qaidam basin, and the relative contents of different carbon number alkan-2-ones were calculated according to the chart of mass chromatogram of samples. The distribution character of alkan-2-ones,alkan=3-ones and alkan-4,ones is similar in one sample; and there is a great change in the distribution of alkan-2-ones in the vertical pro- files. The CPI of alkan-2-0nes ranges from 1.20-1.80, and value of L/H ranges from 0.30-1.61. Based on the characteristics of alkan-2-ones distribution and biomarker parameters, and combined with the geological background of the samples, the source of aliphatic ketones in biogeneic gas source rock in the Quaternary of the Qaidam Basin were discussed, we think that the aliphatic ketones derived from biomass in saline-subsaline lacustrine deposits of the Quaternary of Qaidam basin or from the biodegradation of alkanes by bacterial community.