Coal samples taken from the Taiyuan Formation in the Hequ area, China, for this study are typical cutinite-rich coals. The petrology and geochemistry of the samples were analyzed using microscopic examination, proximate and ultimate analysis, rock pyrolysis, and gas chromatography-mass spectrometry (GC-MS). The cutinites in Haochuan (HC) coals are predominantly of the thin-walled type, whereas those in the Jingzigou (JZG) coals are predominantly thick-walled. The variable thickness of cutinites in different coals is related to the environment in which the coal-forming plants grew. Compared with typical III kerogens, HC and JZG bituminous coals are characterized by high volatile matter yields and hydrogen contents due to the elevated hydrogen-rich cutinite content. Pyrolysis data indicate that these cutinite-rich coals can be expected to generate commercial liquid and gaseous hydrocarbons. Pristane (Pr) and phytane (Ph) are both abundant in the samples, with the Pr/Ph ratios for both the HC and JZG coals being >3.0, indicating moderate maturity and oxic peat depositional conditions. The C-29 >> C-28>C-27 normalized relative abundance of regular steranes is consistent with a dominant contribution from higher plants. Abundant hopanes in the coals also suggest a substantial organic matter input from bacteria, which are common inhabitants of peat and coal. Palynology studies indicate that pteridophytes are likely to be the most common coal-forming plants. A gymnosperm contribution is also indicated by the presence of tetracyclic diterpenes. Massive accumulations of cuticles as cutinite in coal are rare and account for only a small proportion of coals worldwide. However, cutinite-rich coals are found in the northern margin of the North China Craton, in the Taiyuan Formation. The accumulation of cutinite in this area is the result of distinctive peat deposition conditions. Frequent marine transgression was an important contributing factor.
