三环萜烷系列化合物的相对丰度对揭示有机质来源、沉积环境和热演化程度等具有重要 意义。常规煤系烃源岩三环萜烷含量通常偏低，然而在鄂尔多斯和塔里木盆地煤系烃源岩中却检 测到了异常高丰度的三环萜烷（相对于藿烷），因此深入探讨其分布模式、组成特征及成因机制具 有重要意义。采用常规地球化学分析方法和色谱—质谱技术，对研究区的30 个煤系烃源岩样品的 分子地球化学特征进行了详细剖析。研究表明，煤系烃源岩中三环萜烷呈现2 种不同丰度模式：低 丰度三环萜烷（ΣTT/C30H<2）和高丰度三环萜烷（ΣTT/C30H>2）。低丰度三环萜烷样品表现为 C19-21TT 下降型分布模式，形成于淡水偏氧化环境，生烃母质以高等植物为主，热演化程度为低成 熟；高丰度三环萜烷样品则以C23TT 或C21TT 为主峰，形成于咸化、富硫的沉积环境，生烃母质主要 为细菌及低等水生生物，热演化程度达到成熟—高熟阶段。通过成熟度、沉积环境及母质输入相 关参数与ΣTT/C30H值的相关性分析发现，表征沉积环境和生烃母质的参数与ΣTT/C30H值的相关 性更为显著。研究结果表明，偏咸化、高硫含量的成煤环境及生烃母质中高等植物经微生物改造 生成的次生产物输入的增加是煤系烃源岩抽提物中高丰度三环萜烷形成的主要控制因素，而成熟 度则为次要影响因素。煤系烃源岩中高丰度三环萜烷的组成特征及成因机制研究，为煤系油气勘 探与评价提供了重要的指示意义。

Abstract：The relative abundance of tricyclic terpanes has significant indicative value for revealing organic matter sources, depositional environments, and thermal evolution stages. While traditional coal-measure source rocks typically exhibit low tricyclic terpanes content, anomalously high abundances of tricyclic terpanes (relative to hopanes) have been detected in coal-measure source rocks from the Ordos and Tarim Basins. Therefore, an indepth investigation of their distribution patterns, compositional characteristics, and formation mechanisms is of substantial significance. This study employed conventional geochemical analysis methods and gas chromatography-mass spectrometry (GC-MS) to systematically analyze molecular geochemical characteristics of 30 coal-measure source rock samples from the study area. The research demonstrates that tricyclic terpanes in coal-measure source rocks present two distinct abundance patterns: low abundance tricyclic terpanes (ΣTT/C30H <2) and high abundance tricyclic terpanes (ΣTT/C30H>2). The low abundance tricyclic terpane samples exhibit a C19-21TT decreasing distribution pattern, formed in freshwater oxidizing environments, with hydrocarbongenerating parent material primarily derived from higher plants, and at low thermal maturity. The high abundance tricyclic terpane samples display distribution patterns with C23TT or C21TT as the dominant peak, formed in saline, sulfur-rich depositional environments, with hydrocarbon-generating parent material mainly sourced from bacteria and lower aquatic organisms, reaching mature to highly mature thermal evolution stages. Correlation analysis between maturity, depositional environment, and parent material input parameters with Σ TT/C30H values reveals that parameters characterizing depositional environment and hydrocarbon-generating parent material show more significant correlation with tricyclic terpane abundance. The results indicate that brackish, high-sulfur coal-forming environments and increased input of secondary products generated by microbial transformation of higher plants in hydrocarbon-generating parent material are the primary controlling factors for high abundance tricyclic terpanes in coal-measure source rock extracts, while thermal maturity serves as a secondary influencing factor. The molecular composition and formation mechanisms of high-abundance tricyclic terpanes in coal-measure source rocks offer critical molecular geochemical evidence for recognizing coal-forming environments, identifying hydrocarbon-generating organic matter, and assessing thermal maturity, thereby providing theoretical and practical guidance for coal-measure hydrocarbon exploration.