A 90 m-thick coal seam in the Lubstów lignite deposit (Central Poland): palynological analysis and sedimentary environment

A 90 m-thick brown coal seam, the result of organic matter deposition in a fault-trough, is exploited in an open cast mine at Lubstów (Central Poland). Palynological analysis was conducted in order to determine which plants were the source of or ganic matter forming such a thick coal bed. The pollen spectrum is dominated by the gymnosperm pollen Inaperturopollenites, produced by trees closely related to the extant genera Taxodium and Glyptostrobus, the dominant constituents of swamp forests in SE North America and SE Asia today. However, the lack of xylites and preserved tissues in the coal does not support the conception of a swamp forest as the peat-producing community. There is also a significant percent age of angiosperm pollen in the coal, mainly from the groups: Castaneoideapollis, Tricolporopollenites exactus and T. pseudocingulum. The plants producing these pollen were probably the main constituent of the peat-producing community. The community shows signs of a shrub swamp with local tree islands and a low water table. Evidence for this also includes the de trital type of coal, the lack of preserved plant tissues and the presence of fungal remains. These character is tics show the existence of aerobic zones at the time of peat production. The peat was probably derived from angiosperms. Dome-shaped forms in the up per part of the de posit are the re mains of tree is lands. As de tri tus ac cu mu la tion is very rapid on the sur faces of pres ent-day tree is lands, a sim i lar rate of de po si tion may have taken place dur ing peat pro duc tion at Lubstów. This, com bined with sub si dence in the fault-trough, ex plains the great thick ness of the coal bed.