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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.

Uwagi o wyznaczaniu współczynnika kompakcji ksylitów dla pierwszego środkowopolskiego pokładu węgla brunatnego w centralnej Polsce

Widera M.

Przegląd Geologiczny

2013

Vol. 61, nr 5

304–-310

The First Middle-Polish lignite seam of Middle Miocene age is exploited in all opencast mines in the Konin-Turek area, central Poland. This lignite seam contains a large number of xylites, for which the compaction coefficient was calculated as equal to 1.2. On the other hand, it is known that the compaction coefficient for the whole 1st Middle-Polish lignite seam is approximately 2.0. It follows that the compaction coefficient of xylites is 60% of the compaction coefficient for the whole lignite seam. Therefore, the compaction coefficient for the 1st Middle-Polish lignite seam can be easily determined on the basis of the compaction coefficient of xylites. In contrast to other methods, compaction studies of xylites are characterised by easy measurements and simple calculations, and allow neglecting, e.g., post-sedimentary deformation of the lignite seam.