Abstract Late Miocene samples from the Xiaolongtan Formation in Puyang Basin were sampled systematically from bottom to top of the main coal seam. Organic petrological as well as geochemical methods have been applied, aiming at the reconstruction of the depositional environment. The studied samples contain abundant detrovitrinite and liptinite macerals with high ash but low to moderate sulfur contents. This data indicates that the samples were deposited in topogenic mires without marine influence, but with fluctuations of water table and/or water influx which are mirrored by ash and sulfur content. The low values of tissue preservation and vegetation index, but high values of gelification index and groundwater index (GWIAC) in the studied coal imply a peat accumulation in inundated marshes under slightly oxic to anoxic depositional conditions with input of herbaceous plants mainly. An extended data set on vitrinite reflectance, volatile matter, Rock-Eval Tmax and HI suggests a coalification ranging from subbituminous C to B coal. The high concentration of long chain n-alkanes in the studied samples is typical for kerogen derived predominately from higher terrestrial plants. The applied biomarker ratios together with the detected hopenes further confirm the low thermal maturity level, as well as high water table and terrestrial organic matter input during peat accumulation. The variable concentrations of terpenoids and sesquiterpenoids suggest a dominant angiosperm input, but with a relatively high proportion of gymnosperms during some periods of peat deposition.

中文翻译：

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云南濮阳盆地低熟煤沉积史

摘要 对濮阳盆地小龙潭组晚中新世主煤层自下而上进行系统采样。已应用有机岩石学和地球化学方法，旨在重建沉积环境。研究的样品含有丰富的底晶质和 liptinite maerals，具有高灰分但低至中等硫含量。该数据表明，样品沉积在没有海洋影响的地形泥沼中，但随着灰分和硫含量反映了地下水位和/或水流入量的波动。组织保存和植被指数低，但所研究的煤中凝胶化指数和地下水指数 (GWIAC) 的高值表明，在主要输入草本植物的轻度好氧至缺氧沉积条件下，淹没沼泽中的泥炭积累。关于镜质体反射率、挥发分、Rock-Eval Tmax 和 HI 的扩展数据集表明煤化作用范围从亚烟煤 C 到 B 煤。研究样品中高浓度的长链正构烷烃是主要来自高等陆生植物的干酪根的典型特征。应用的生物标志物比率以及检测到的希望进一步证实了泥炭积累过程中的低热成熟度水平以及高地下水位和陆地有机质输入。萜类化合物和倍半萜类化合物的不同浓度表明被子植物占主导地位，