Organic Geochemistery of Terpanes in Saturated Hydrocarbons from Coal and Exinite in Pyrolysis Under Closed System
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摘要: 通过对塔里木盆地煤岩与壳质组热模拟实验可溶有机物的色—质分析,煤岩和壳质组三环二萜烷具有低丰度、窄碳数(C19~C26)特征,且三环二萜烷主要来源于煤岩结构中具有三环萜骨架前身物的断裂释放。藿烷C31和C32-αβ22S/22(S+R)随着热模拟温度升高呈增加趋势,表明该地球化学参数是较好的热成熟度指标;αββ藿烷可以用来反映煤岩的热演化程度,且ββ构型向βα构型转化时需要一定能量;煤岩在未熟到成熟热演化过程中,藿烷具有ββ<βα<αβ的热稳定性。壳质组萜烷系列化合物的地球化学参数(以17β(H)三降藿烷、C29βα-藿烷、C31αβ22S/22(S+R))表明壳质组热演化史比煤岩有迟豫效应。Abstract: According to the GC-MS analysis of soluble organic matters extracted from coal and exinite heated in closed system pyrolysis, one characteristic feature of all samples is the relative low abundance of tricyclic diterpanes in saturated hydrocarbon fractions with the detection in the C19 to C26 range. The tricyclic diterpanes and its homologues are derived from the cleavage and release of their precursors in coal framework. The positive linear correllation between 22S/22(S+R) ratios of C31C32αβ hopanes and pyrolysis temperatures indicates that they would be used as the thermal mature parameters. The detection of αββ hopanes in saturated hydrocarbons infers the low maturity of coal samples and the energy for conversion of 17β (H),21β(H)-homohopanes to 17β(H),21α(H). During the thermal evolution of coal rock from low to high maturity, the thermal stability of hopanes is as follows: ββ<βα<αβ. The time of hydrocarbon generation from exinite is later than coal according to the geochemical parameter of hopanes, such as occurrence of 17β(H) trisnorhopane and C29βα-hopanes as peak carbon, C31αβ22S/22(S+R) index.
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Key words:
- coal rock /
- exinite /
- thermal pyrolysis /
- terpanes
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