Molecular Biomarkers Characteristics of Source Rocks from Tanhai Sanma Area in the Huanghua Depression and Its Signification for Sedimentary Facies
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摘要: 通过对黄骅坳陷滩海三马地区浊流沉积层序的生物标志物组合差异特征研究，揭示出分子标志物对该地区沉积相的指示意义。样品中除了含有丰富的正构烷烃、类异戊二烯烷烃、甾烷和藿烷系列化合物外，还普遍检测到了伽马蜡烷和标志着陆生高等植物来源的奥利烷，其中Pr/Ph为1.00～3.03；Ts/Tm为1.1～9.11；奥利烷/C30藿烷为0.09～1.48；伽马蜡烷/C30藿烷为0.08～1.03。对生物标志物的综合分析表明，三马地区沙一段烃源岩沉积时期为淡水—微咸水—半咸水的弱还原—氧化条件环境；同一剖面相同层段中(几米内)巨大的生物标志物指纹差异分布，证明了该地区重力流沉积这一地质现象，同时较为清晰地指示出混源相沉积物与浊积岩相互叠置界线。由此认为，该套地层的形成应该是以重力流形式携带大量载荷直接补给湖盆内并快速沉积，然后，在浊流发生的间歇期，上覆湖相沉积物，从而形成互层的砂泥岩层序结构。Abstract: Abundant molecular biomarkers，including nalkanes，isoprenoid，steranes and terpanes，are detected by GCMS in mudstone and sandstone samples from Tanhai Sanma area in the Huanghua Depression. Some typical biomarkers，such as Gammacerane and Oleanane，which can be used to determine the nature of organic matter，are also been founded in samples. The ratio of Pr/Ph is ranging from 0.54 to 3.03，the Ts/Tm is from 1.1 to 9.11，the O/C30H is from 0.005 to 1.48 and the G/C30H is from 0.03 to 1.03，the parameters of molecular biomarkers in Sanma area have distinct difference which reflected the depositional environment under weak oxidation or deoxidize，and are in close relationship with organic matter import and sedimentary environment. Especially，the parameters of biomarkers distributions in mudstone is different at the same section sequence. The results show that the sequence boundary characteristic between turbidite sediment and the mixed was obvious，and it is easy to see that there exists a close link between them. The whole process of the formation is a complete turbidite depositional sequence and a mixed layer that made up of terrestrial origin and algae import formed in the interval of turbidity event.
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Key words:
- Huanghua depression /
- Sanma area /
- molecular biomarker /
- sedimentary facies /
- sedimentary environment
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