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Osady glifu krewasowego z miocenu Polski środkowej w okolicach Konina

Widera M., Chomiak L., Gradecki D., Wachocki R.

Przegląd Geologiczny

2017

Vol. 65, nr 4

251--258

The paper presents results of a study of crevasse splay deposits from the Miocene of central Poland near Konin. These mineral deposits occur within the 1st Middle-Polish lignite seam of Middle Miocene age, which is exploited from the Tomislawice lignite opencast mine. They consist of fine-grained sands with an admixture of plant detritus at the top and bottom layers, where the muddy-sandy clasts are present. The investigated crevasse splay deposits are predominantly massive or horizontally stratified, and they occasionally reveal small- to large-scale (planar, trough and ripple) cross-stratification. Thus, they are interpreted as representing dense gravity flows, sheet flows, and channelized flows of variable energy. The crevasse splay was formed subaerially during sudden flood conditions on the floodplain covered by a low-lying mire with predominant herbaceous vegetation. The description of the crevasse splay deposits from the Miocene of central Poland can be helpful in better understanding the sedimentation conditions of relatively thick lignite seams.

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

Durska E.

Geological Quarterly

2008

Vol. 52, No 3

281-281

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.