Characteristics of Biomarker Compounds and Its Implication of Middle Jurassic Oil Shale Sequence in Shuanghu Area, Northern Tibet Plateau
Characteristics of Biomarker Compounds and Its Implication of Middle Jurassic Oil Shale Sequence in Shuanghu Area, Northern Tibet Plateau
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发表时间：
2001
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通讯作者：
Lin Jin
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作者：
Lin Jin
在藏北高原双湖地区中侏罗世油页岩中，GC-MS检测到丰富的正构烷烃、类异戊二烯、甾烷和萜烷等生物标志物，正构烷烃的碳数为n C12 n C35，碳数范围较广，以n C15、n C16或n C17为最高峰。对相对丰度的检测表明，正构烷烃中的低碳分子组分占主导地位。油页岩中Pr/Ph比值在0.77~1.59之间，在垂直剖面上波动较大。油页岩上部和下部以绿柱烷为主，油页岩序列中部以植烷为主。C30正庚烷是正庚烷系列中含量最丰富的。按相对丰度计算，有五环三元烷、三环三环萜烷、四环萜烷。SteraneΣC27/ΣC29比值为0.79~1.20，Σ(C27+C28)ΣC29。油页岩下部甾烷的碳数分布显示C27组分略占优势，油页岩上部C29组分略占优势。C27非甾烷/C27甾烷比值在0.51~3.63之间，在垂直剖面上也有波动。这表明有机质来自藻类，并有适当比例的陆源贡献。油页岩中的有机质发育成熟。不同的Pr/Ph和C27非甾烷/C27甾烷在评价沉积环境的变化和认识有机质的保存潜力方面特别有用。
Abundant biomarkers, including n alkanes, isoprenoid, steranes and terpanes, have been detected by GC—MS from the middle Jurassic oil shales in the Shuanghu area, northern Tibet plateau.N alkanes contain carbon number n C 12 n C 35 with a relatively wide range, n C 15 , n C 16 or n C 17 as the highest peak. Examination of the relative abundance show a dominance of low carbon molecular components in the n alkane. Pr/Ph ratio in oil shales range from 0.77 to 1.59, and it fluctuates in the vertical section. The upper and lower part of the oil shales have slight predominance of pristane, whereas phytane dominates in the middle part of the oil shale sequence. C 30 hopane is the most abundant in the hopane series. According to the relatively abundance, pentacyclic triterpane tricyclic terpane quartcyclic terpane. Sterane ΣC 27 /ΣC 29 ratio ranges from 0.79 to 1.20, and Σ(C 27 +C 28 ) ΣC 29 . The carbon number distribution of the steranes show a slight predominance of C 27 components over C 29 in the lower part of the oil shales and a slight dominance of C 29 component over C 27 in the upper part of the oil shales sequence. C 27 diasterane/ C 27 sterane ratio range from 0.51 to 3.63, which also fluctuate in the vertical section. It indicates organic matter of algael origin, with proper ratio contribution from terrestrial sources. The organic matter in the oil shales is mature. Different Pr/Ph and C 27 diasteranes/C 27 steranes proved especially useful in assessing variation in depositional environment and recognizing preservation potential of the organic matter.