The study on the Zhangjialiang No. 2 coal of Middle Jurassic Yan'an Formation in the northeastern Ordos Basin has been analyzed by gas chromatography-mass spectrometry (GC-MS) to determine geochemical characteristics and reconstruct palaeovegetation and palaeoclimate changes. The distribution of n-alkanes is mainly unimodal, with a medium and high molecular weight. Pr/Ph ratio (2.03–10.6) is high in most samples. The values of Tm/Ts ratio are between 1.42 and 4.92, and a predominance of C₂₉ over C₂₇ steranes has been found for the analyzed samples. These parameters indicate that all samples were deposited in an oxidizing freshwater environment, and the organic matter was mainly derived from terrestrial higher plants, with a small amount of aquatic organisms. Thermal maturity parameters such as C₃₁22S/(22S + 22R) homohopane, C₃₀αβ/(αβ + βα) hopane, together with the total organic carbon (TOC) contents (43.1% - 58.6% (except floor 2-13)) and the detected of C₂₇17β(H)-22, 29, 30-trisnorhopane (βTm), suggest that most of samples have a relatively low maturity in the early stage. Besides, gymnosperm-derived biomarkers, including labdane, norpimarane, isopimarane, phyllocladane, abietane, rimuane, ent-beyerane, ent-kaurane, suggest that the vegetation during the Middle Jurassic Yan’an Formation was characterized by conifers.

对鄂尔多斯盆地东北部中侏罗统延安组张家梁2号煤进行了气相色谱-质谱（GC-MS）分析，确定了地球化学特征，重建了古植被和古气候变化。正构烷烃的分布主要是单峰的，具有中等和较高的分子量。大多数样品中的 Pr/Ph 比 (2.03–10.6) 很高。Tm/Ts 比值介于 1.42 和 4.92 之间，C ₂₉优于 C ₂₇已在分析的样品中发现了甾烷。这些参数表明，所有样品均沉积在氧化性淡水环境中，有机质主要来源于陆生高等植物，少量水生生物。热成熟度参数，例如 C ₃₁ 22S/(22S + 22R) 高藿烷、C ₃₀ αβ/(αβ + βα) 藿烷，以及总有机碳 (TOC) 含量（43.1% - 58.6%（2-13 层除外） ) 和检测到的 C ₂₇17β(H)-22, 29, 30-三降藿烷(βTm)表明大部分样品早期成熟度较低。此外，裸子植物来源的生物标志物，包括labdane、norpimarane、isopimarane、phyllocladane、abietane、rimuane、ent-beyerane、ent-kaurane，表明中侏罗世延安组植被以针叶树为特征。