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本文研究了陕北地区三叠系延长组长1段烃源岩的生物标志化合物特征及其有机质母源类型和有机质成熟度。利用气相色谱和色谱—质谱技术检测了长1段烃源岩中的正构烷烃、异戊二烯烃、萜烷和甾烷四类生物标志化合物。研究结果表明,长1段湖相泥岩有机质中富含低碳数正构烷烃、姥鲛烷、Ts以及胆甾烷,其生源类型主要是水生低等生物,三角洲平原相泥岩有机质中富含高碳数正构烷烃、Tm及谷甾烷和麦角甾烷,其生源类型主要是陆源高等植物。萜烷和甾烷的异构化指数表明长1段烃源岩有机质已达到成熟阶段。本项研究结果对于重新认识陕北地区长1段烃源岩的分布及有机地球化学特征具有重要的意义。
In this paper, the characteristics of biomarker compounds, organic source types and organic matter maturity of the source rocks of the Member 1 of the Yanchang Formation in the Triassic Yanchang Formation in northern Shaanxi Province were studied. Four biomarkers of n-paraffin, isoprene, terpane and sterane were detected by GC and GC-MS. The results show that the organic matter in the Chang 1 Member mudstone is rich in low-carbon n-alkanes, pristane, Ts and cholestane. The biogenic types are mainly low-water organisms. The organic matter in the delta plain mudstone is rich in high Carbon number n-alkanes, Tm and sitostanes and ergostane, the source type is mainly terrestrial higher plants. The isomerization index of terpanes and steranes indicates that the organic matter of the source rocks of the Chang 1 member has reached the mature stage. The results of this study are of great significance for the re-understanding of the distribution and organic geochemical characteristics of the Chang 1 member of source rocks in northern Shaanxi.