腐殖煤三环萜烷类化合物差异影响与分布模式OA北大核心CSTPCD

The Upper Paleozoic coal-measure source rocks in the Ordos Basin,the Mesozoic coal-measure source rocks in the Tarim Basin,and the Mesozoic coal-measure source rocks in the Junggar Basin are extensively developed,enriched with tricyclic terpane content in humic coal.There are significant differ-ences in the distribution patterns of tricyclic terpane(TT),absolute concentrations,and the ratios of compounds with different carbon numbers among the samples.The macroscopic geochemical character-istics,saturated hydrocarbon and aromatic hydrocarbon biomarkers of 28 humic coal samples were stud-ied by organic geochemical methods and chromatography-mass spectrometry.The effects of aromatic hydrocarbon maturity,sedimentary environment and hydrocarbon-forming parent materials on the differences and distribution patterns of tricyclic terpanes were discussed.The results show that the hu-mic coal samples are divided into two types.Type Ⅰ humic coal has C19 TT as the main peak,high Pr/Ph value and high relative abundance of C24 tetracyclic terpane(C24 TeT).The main peak of type Ⅱ hu-mic coal is C23 TT,the Pr/Ph value is low,and the relative abundance of C24TeT is low.There is no sig-nificant correlation between C19TT/C23TT value and aromatic maturity parameters(F1,F2,4-MDBT/1-MDBT),suggesting that the difference in the distribution pattern of tricyclic terpane in different types of humic coal is less affected by the thermal evolution of organic matter.The correlation between the C19 TT/C 23 TT value and the aromatic hydrocarbon parameters related to the sedimentary environment re-veals that there is a clear zoning between the type Ⅰ humic coal and the type Ⅱ humic coal samples,and the reducibility of the sedimentary environment of the type Ⅱ humic coal samples is stronger than that of the type Ⅰ humic coal.Seawater action leads to the change of sedimentary environment.The trans-formation of higher plants by microorganisms makes the hydrocarbon-forming parent material of type Ⅱhumic coal different from that of type Ⅰ humic coal with original higher plants as hydrocarbon-forming parent material.The results provide useful geochemical parameters for the application of biomarker compounds in oil and gas exploration.