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Architektura i geneza iłów w górnym poziomie węgli brunatnych formacji poznańskiej (środkowy miocen) : Odkrywka Tomisławice k. Konina w środkowej Polsce

Chomiak Lilianna, Urbański Paweł, Widera Marek

Przegląd Geologiczny

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2020

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Vol. 68, nr 6

526--534

EN

In the Tomisławice opencast mine, owned by the Konin Lignite Mine, a relatively widespread (>1.5 km2) and thick (up to 80 cm) layer of clay occurs within the first mid-Polish lignite seam. These fine-grained sediments are interpreted as deposited in a long-lasting lake that existed in the mid-Miocene backswamp area. Due to the exploitation of this seam forelectricity production, interbeddings of clastic sediments significantly reduce the quality of lignite. Currently, lignite is mined together with the clays in the Tomisławice opencast mine. Such procedure in extreme cases, where the maximum. thickness of the clay layer is up to 80cm, increases/may increase the ash content of the entire lignite seam almost twice. Therefore, selective lignite mining would be recommended, i.e. without clays, which unfortunately is not practiced due to technological and financial reasons.

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Crevasse splays within a lignite seam at the Tomisławice opencast mine near Konin, central Poland: architecture, sedimentology and depositional model

Chomiak Lilianna

Geologos

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2020

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Vol. 26, No. 1

25--37

EN

The present article focuses predominantly on sandy deposits that occur within the Middle Miocene lignite seam at the Tomisławice opencast mine, owned by the Konin Lignite Mine. As a result of mining activity, these siliciclastics were available for direct observation in 2015–2016. They are situated between two lignite benches over a distance of ~500 m in the lower part and ~200 m in the higher part of the exploitation levels. The maximum thickness of these sandy sediments, of a lenticular structure in a S–N cross section, is up to 1.8 m. With the exception of a thin lignite intercalation, these siliciclastics comprise mainly by fine-grained and well-sorted sands, and only their basal and top layers are enriched with silt particles and organic matter. Based on a detailed analysis of the sediments studied (i.e., their architecture and textural-structural features), I present a discussion of their genesis and then propose a model of their formation. These siliciclastics most likely formed during at least two flood events in the overbank area of a Middle Miocene meandering or anastomosing river. Following breaching of the natural river levee, the sandy particles (derived mainly from the main river channel and levees) were deposited on the mire (backswamp) surface in the form of crevasse splays. After each flooding event, vegetation developed on the top of these siliciclastics; hence, two crevasse-splay bodies (here referred to as the older and younger) came into existence. As a result, the first Mid-Polish lignite seam at the Tomisławice opencast mine is currently divided in two by relatively thick siliciclastics, which prevents a significant portion of this seam from being used for industrial purposes.

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Sedimentation of Lower Toarcian (Lower Jurassic) brackish deposits from the Częstochowa-Wieluń region (SW Poland)

Leonowicz P.

Acta Geologica Polonica

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2011

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Vol. 61, no. 2

215-241

EN

The Lower Toarcian Ciechocinek Formation from the Częstochowa-Wieluń region is composed of poorly consolidated mudstones, claystones and siltstones with subordinate sandstone intercalations. The succession is represented by twelve lithofacies grouped into seven facies associations of a shallow brackish marine basin with an embayment character. The sedimentation was dominated by clay and silt deposition from low-density suspension flows, spreading out from river mouths, and from suspension clouds whirled up during storms. Sand intercalations mark episodes of storms, removing coarser material from nearshore to more distal settings, migration of elongated sand bars, as well as sedimentation at river mouths and on sandy shoals. The deposition was affected by three main factors: (1) progradation and displacement of river mouths; (2) river discharge fluctuations;and (3) short-term weather changes.

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Uwagi na temat wybranych klasyfikacji frakcjonalnych osadów klastycznych – problem różnic w przedziałach klasowych i nazewnictwie

Szmańda J. B., Krzemień K.

Landform Analysis

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2008

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Vol. 9

381--384