Methods of optical microscope, X-ray fluorescence spectrometry (XFS) and inductively coupled plasma mass spectrometry (ICP-MS) have been used to determine macrolithotype and microlithotype of coal, geochemical parameters of the No.5 coal seam in the Taiyuan Formation, Tashan minefield, Datong coalfield; coal petrology, geochemical and coal facies characteristics discussed; and coal seam primary coal-forming peat bog environment and evolutionary pattern systematically analyzed as well. The results have demonstrated that: No.5 coal seam has four facies types, namely limnetic facies, peat bog facies, humid and rather dry forest-swamp facies, correspondingly shown as lacus, back-barrier lagoon, upper delta plain and flood basin coal-bearing systems characteristics.From bottom to top, coal seams show 5 distinct sedimentary cyclic rhythms, correspondingly environment aqueous media vary from oceanic-continental, brine-fresh water alternatively. Accordingly, a set of mainly terrestrial and transitional marine to limnic facies coal-forming peat bog environment formed, and gradually evolved from marine, marine-limnic to terrestrial facies.%采用光学显微镜、X射线荧光光谱(XFS)和电感耦合等离子体质谱(ICP-MS)等方法测定了大同煤田塔山井田太原组5号煤的宏观煤岩类型、显微煤岩类型和地球化学参数,探讨了煤的煤岩学、煤地球化学及煤相特征,系统地分析了煤层的原始成煤泥炭沼泽环境及演化规律.研究结果表明,5号煤层有4种煤相类型,即湖沼相、泥炭沼泽相、潮湿森林沼泽相和较干燥森林沼泽相,相应表现为湖泊、障壁岛后潟湖、上三角洲平原和洪泛盆地含煤沉积体系特征.煤层自下而上存在5次比较明显的沉积旋回韵律,与之相随的水介质环境也发生了相应的海陆、咸水、淡水交替变化,从而形成了一套以陆相为主、海陆交互的成煤泥炭沼泽环境,沉积环境逐渐从海相、海陆过渡相向陆相演化.
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