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1

Ewolucja paleomorfologiczna i paleotektoniczna elewacji konińskiej

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Widera M.

Geologos

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1998

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tom Vol. 3

55--103

PL

Elewacja konińska położona jest w środkowej części niecki mogileńsko-łódzkiej. Niemniej jednak badany obszar charakteryzuje wysokie i płytkie występowanie paleopowierzchni mezozoicznej. Strop mezozoiku budują skały późnej kredy. Należą do nich wczesnomastrychckie margle, „opoki”, gezy oraz sporadycznie wapienie i piaskowce. Paleorzeźba mezozoiku jest o wiele bardziej urozmaicona niż współczesna morfologia terenu. Deniwelacje powierzchni podkenozoicznej mieszczą się w przedziale wysokości od +116 m n.p.m. w okolicach Turku do poniżej -180 m p.p.m. w okolicach Lubstowa. Wysoka pozycja elewacji konińskiej jest łączona ze strukturami solnymi: poduszkami i diapirami, które zalegają na głębokości 5-7 km. Również geneza największych depresji w stropie mezozoiku jest wiązana głównie z aktywnością soli (halotektonika), a nawet z subrozją. W kopalniach węgla brunatnego udokumentowano liczne uskoki. W rzeźbie powierzchni podkenozoicznej zaznaczają się zręby i rowy tektoniczne. Największe obszary, wypełnione m.in. miąższymi pokładami węgla brunatnego, to rowy tektoniczne: Lubstowa, Niesłusza-Gosławic, Kleczewa, Piasków, Władysławowa i Adamowa. Na obszarach rowów pokłady węgla brunatnego osiągają miąższość do ponad 90 m. Są to jednak grubości wyjątkowe, bowiem najczęściej warstwy węglowe mieszczą się w przedziale od kilku do kilkunastu metrów. Wspomniane obszary zostały poddane bardziej wnikliwym badaniom niż tereny międzyrowowe. Morfologia spągu węgli została bardzo dobrze rozpoznana, a następnie porównana z ukształtowaniem stropu mezozoiku. Subsydencja mezozoicznego podłoża była kompensowana przez akumulację substancji organicznej. Dlatego też deformacje tektoniczne zarejestrowano w spągowych warstwach węgli brunatnych. Powierzchnia mezozoiku była przekształcana także przez procesy denudacji i erozji w paleocenie oraz częściowo między eocenem i pliocenem. W plejstocenie powierzchnię podkenozoiczną niszczyły lądolody skandynawskie i ich wody roztopowe. Współcześnie paleopowierzchnia mezozoiczna podlega zmianom w wyniku krasu oraz działalności gospodarczej człowieka w odkrywkach węgla brunatnego, a częściowo także w drobnych wyrobiskach „opok”. Główne zdarzenia tektoniczne na badanym obszarze są porównywane z fazami diastroficznymi w Karpatach i Sudetach. W fazie laramijskiej (mezozoik/kenozoik) region koniński podlegał ruchom wznoszącym. W fazie sawskiej (oligocen/miocen) elewacja konińska osiągnęła prawdopodobnie współcześnie rejestrowane rysy morfologiczne z generalnym nachyleniem w kierunku N i W. Wtedy też istniała już większość badanych rowów tektonicznych. W fazie styryjskiej (środkowy miocen) rozwój wspomnianych rowów był najintensywniejszy, co zaznaczyło się w warunkach ciepłego i wilgotnego klimatu umiarkowanego powstaniem miąższych złóż węgla brunatnego.

EN

The Konin Elevation is located in the centre part of greater geological structure called the Mogilno-Łódź Depression. The investigated area is characterized by a high position and shallow occurrence of the Mesozoic palaeosurface. The top of the Mesozoic is built of Late Cretaceous rocks. They consist of Early Maastrichtian: marls, opokas, gaizes as well as occasionally limestones and sandstones. The Mesozoic palaeorelief is much more varied than the contemporary morphology. Generally speaking, the sub-Cainozoic relief of the described elevation is developed between 116 m asl. in the Turek area and 180 m bsl. in the Lubstów area. The high position of the Konin Elevation is linked with salt structures, such as pillows and diapirs, which occur at a depth of 5000-7000 m. As well as the genesis of the greatest depressions is mainly connected with salt activity (halotectonics) and perhaps even subrosion. Halotectonic processes took place in studied area in Tertiary and during Quaternary. The Mesozoic surface was deformed also by processes of denudation and erosion in the Palaeocene, occasionally during the period between the Eocene and the Pliocene. In the Pleistocene the sub-Cainozoic substratum was damaged by the Scandinavian icecups and their waters. Nowadays, the palaeorelief under study is changed by krast and human activity in the lignite and opoka outcrops. There is the deepest depression where the Mesozoic rocks have not been reached up to 180 m bsl. in the Lubstów graben. A lot of faults, dislocations and other tectonic structures have been documented in the lignite mines. The sub-Cainozoic relief is marked by tectonic grabens and horsts. There are the most important grabens with thick lignite deposits in the areas of: Lubstów, Niesłusz-Gosławice, Kleczew, Piaski, Władysławów, Adamów. The thickest lignite deposits up to 90 m have been noticed in the mentioned grabens. These areas have been investigated much more better than other regions of the Konin Elevation. The relief of the bottom surface of the lignite has been known very well and compared with the morphology of the Mesozoic substratum. Both palaeosurfaces have been deformed by the tectonic processes. The subsidence of the Mesozoic top in the grabens has been compensated by the accumulation of organic matter. That is why the tectonic deformations have been noticed in the bottom layers of the lignite. The main tectonic events that have happened in study area are comparable to the major diastrophic phases in Carpathians and Sudetes. In the Laramie phase (Mesozoic/Cainozoic) the whole Konin region was elevated. A general inclination of the Konin Elevation towards N and W is connected with the Savian phase (Oligocene/Miocene), when a great number of tectonic grabens became existed. In the Styrian phase (Middle Miocene) the development of block- -faulting grabens was the most intensive. At that time the greatest lignite deposits were formed in particular conditions similar to the mediterranean and even subtropical climate.

2

Slump folds within mid-Miocene crevasse-splay deposits : a unique example from the Tomisławice lignite opencast mine in central Poland

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Widera M.

Geological Quarterly

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2020

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tom Vol. 64, No. 3

711--722

EN

Non-tectonic, soft-sediment deformation structures occur in mid-Miocene crevasse-splay deposits exposed in the Tomisławice lignite opencast mine in central Poland. The crevasse-splay cross-stratified siliciclastic deposits are underlain by continuously folded and relatively thick lignite beds, and overlain by a thin undisturbed layer of lignite. Only the middle part of the crevasse-splay succession is deformed plastically in the form of folds, while the lower and uppermost beds are undeformed. Most of the intraformational deformation structures are recumbent folds, while only a few can be classified as upright folds in the initial stage of their evolution. The origin of these folds is associated here with a penecontemporaneous slumping process caused by liquefaction of sandy-muddy sediments. The slumping was triggered by an increase in the inclination of heterolithic layers caused by the compactional subsidence of an organic-rich substrate - peat. This type of subsidence occurred following a sudden siliciclastic load on top of the underlying and poorly-compacted peat/lignite seam. The initiation and development of the slump folds can be explained by differentiated loading, compaction and liquefaction processes, and the introduction of a tectonic agent is unnecessary.

3

Macroscopic lithotype characterisation of the 1st Middle-Polish (1st Lusatian) Lignite Seam in the Miocene of central Poland

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Widera M.

Geologos

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2012

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tom Vol. 18, No. 1

1--11

EN

The 1st Middle-Polish (1st Lusatian) Lignite Seam is exploited in open-cast mines in central Poland. A large number of lignite lithotypes, grouped in four lithotype associations, are distinguished: xylitic, detritic, xylo-detritic and detro-xylitic lithotype associations, which show various structures. Each lithotype association was produced under specific peat-forming environmental conditions. In the case of the lignite seams under study they represent all the main environments that are known from Neogene mires, i.e.: fen or open water, bush moor, wet forest swamp and dry forest swamp. For a simple and practical description in the field of both the lignite sections and borehole cores, a new codification for lignite lithotypes is proposed. It is based on the codification of clastic deposits (lithofacies). The practical value of the new lignite lithotype codification is examined in three vertical sections of the 1st Middle-Polish Lignite Seam.

4

What can be learned about the deposition and compaction of peat from the Miocene lignite seam exposed in the Chłapowo Cliff on the Polish coast of the Baltic Sea?

100%

Widera M.

Geology, Geophysics and Environment

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2019

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tom Vol. 45, no. 2

111--119

EN

This study focuses on discussing the relationship between the accumulation of peat and its compaction in the overbank zone of the Miocene river system. The examined 2nd Lusatian lignite seam is characteristically interbedded with sandy deposits and these are less compressible than peat. Therefore, in favourable conditions such as those found at Chłapowo Cliff (on the Baltic Sea coast in northern Poland), it is possible to identify the effects of an even or uneven lowering of the mire surface, resulting from diversified compaction of the underlying phytogenic beds. The research problem was applied to two examples located close to each other within the lignite seam. The first case shows the accumulation of fresh peat layers of almost equal thickness, while the second one presents a reduction in the thickness of fresh peat beds over the fossilised channel-fill sandy body. Only the latter example allows us to calculate the peat-to-lignite compaction ratio. The results of the compaction ratio obtained, Cr ≈ 7.37, mean that the youngest, fresh peat layers were compacted at least 7 times, transforming them into lignite beds. However, such a high compaction value, estimated for the top layers of the Miocene mire, cannot be directly taken into account when reconstructing the total thickness of the peat seam prior to covering it with mineral overburden. The published peat-to-lignite compaction ratios, determined using other research methods, for the 2nd Lusatian lignite seam or its stratigraphic equivalents range from 1.7 to 6.0 in most cases, with averages of 2.2 to 4.0. The differences between the data in the literature and the results given in this paper are due to the fact that the process of peat/lignite compaction is ongoing and cumulative.

5

O ujednoliceniu terminologii osadów drobnoziarnistych i zlodowaceń – zainicjowanie dyskusji

100%

Widera M.

Przegląd Geologiczny

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2023

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tom Vol. 71, nr 9

461–-465

EN

Through this article the author wants to initiate a discussion about unifying the terminology used by researchers of various specialties in the field of Earth sciences. This applies to both glaciogenic and other sedimentary environments. First, it is about defining mud. Secondly, there is a need to unify (propose) facies codes for fine-grained clastics. And thirdly, the spelling of the names of Pleistocene glaciations should be resolved.

6

Reconstruction of the sedimentary environment of phytogenic deposits in the Tomisławice opencast mine (Konin Region, central Poland)

63%

Słodkowska B. , Widera M.

Geological Quarterly

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2022

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tom Vol. 66, No. 4

art. no. 34

EN

Palynological analysis of the Tomisławice opencast mine deposits has allowed reconstruction of the plant communities and investigation of the evolution of sedimentary environments at various stages of lignite-forming marsh development, recorded in the composition of pollen assemblages from deposits of the 1st Mid-Polish lignite seam (MPLS-1). Rich pollen communities from an ~9 m thick section has enabled study of the succession of plant communities and of the evolution of phytogenic sedimentation. The pollen succession indicates that the assemblages in the whole lignite seam represent the VIII Celtipollenites verus pollen Zone. Slight differences in the composition of the communities reflect different stages of basin development, depending more on the variable water dynamics than on climatic oscillations. Lignite of the MPLS-1 developed in a continental regime on alluvial plains. Changes in the succession of plant communities in the Tomisławice section record flooding-drainage cycles caused by groundwater level oscillations. Peat bog accumulation took place in river basins, in which the lack of siliciclastic intercalations within the massive lignite seams points to weak fluvial dynamics. A rise in groundwater level and/or surface water resulted in flooding of the marshes and the formation of an extensive shallow lake basin, as shown by the presence of freshwater algae and pollen of aquatic plants. The section as a whole does not record an increased contribution of thermophilic plant taxa. The flora was generally dominated by warm-temperate and thermophilic species, without the participation of strongly thermophilic vegetation, which indicates that the lignite seam in the Tomis³awice opencast mine was formed in the generally stable conditions of a warm temperate climate.

7

Is the Złoczew lignite deposit geologically suitable for the first underground gasification installation in Poland?

63%

Urbański P. , Widera M.

Geologos

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2020

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tom Vol. 26, No. 2

113--125

EN

The present study focuses on alternative methods of exploiting lignite in comparison to conventional opencast mining and combustion in power plants for the generation of electricity. In Poland, opencast lignite pits cover large areas, creating social and environmental conflicts. In order to stabilise the production level of electricity and reduce the negative effects of opencast mining, alternative ways of exploiting lignite are suggested, one of these being underground gasification in situ. The Złoczew lignite deposit, which will most likely be exploited in the near future, provides an opportunity to discuss the unconventional method of underground coal gasification (UCG). On the basis of technological and geological criteria that have been established to determine the suitability of Polish lignite for underground gasification, resources to be used this way have been estimated. Through gasification, over 15 million tonnes of lignite can be utilised, which is about 2.5 per cent of resources of the Złoczew deposit intended for opencast mining. With this in mind, we suggest to take action by starting a pilot installation, to be followed by a commercial one for underground gasification after completion of superficial mining. Naturally, any future application of this method will be preceded by assessment of geological conditions at the Złoczew opencast pit.

8

Various genetic types of end moraines in the city of Poznań and its close vicinity, central-western Poland

63%

Widera M. , Chomiak L.

Civil and Environmental Engineering Reports

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2019

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tom Vol. 29, no. 3

218--227

EN

The current research focuses on explaining the origin of end moraines running through the northernmost districts of the city of Poznań. The highest hills, that is, the Moraska Hill and the Dziewicza Hill, are a stagnation record of the Vistulian Glaciation of the Poznań Phase. These two hills represent terminal moraines of similar height and age, but the mechanism of their formation is diametrically opposed. The Dziewicza Hill is a typical accumulative end moraine, where Pleistocene deposits over 70 m thick are undisturbed. On the other hand, the Moraska Hill is a classic example of a push end moraine with a relatively thin cover of Pleistocene sediments and glaciotectonically elevated (up to 130 m a.s.l.) upper Neogene deposits. In the latter case, these strongly deformed sediments are the so-called "Poznań Clays" that underlie the Quaternary deposits in the vast area of the Polish Lowlands.

9

A comparative study of the oxide and elemental composition of ash from lignite burned at various temperatures – Konin Lignite Mine, Central Poland

63%

Chomiak L. , Widera M.

Gospodarka Surowcami Mineralnymi

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2020

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tom T. 36, z. 4

145--160

EN

Lignite still plays a key role in the production of electricity in Poland. About one-third of domestic electric energy comes from lignite burned in large power plants that produce megatons (Mt) of bottom ash and fly ash annually. Nearly 11 wt% of the total ash generated by the lignite-fired power industry in Poland comes from lignite extracted from the Konin Lignite Mine. Part of the ash escapes into the atmosphere, and the rest is utilized, which is expensive and often harmful to the environment; hence, geochemical studies of these ashes are fully justified and increasingly carried out. The lignite samples examined in this paper represent the entire vertical section of the first Mid-Polish lignite seam (MPLS-1) mined in opencasts at Jóźwin IIB, Drzewce, and Tomisławice. First, the samples were oxidized (burnt) at one of three temperatures: 100, 850, and 950°C; then the chemical composition of oxides and trace elements was determined according to the ASTM D6349-13 standard. The ashes were rich in SiO2 and CaO; Ba, Sr, and Cu dominated the trace element content. Among the harmful elements found, Pb is of most concern. Only a few elements (Ba, Cu, Pb, Sb) reached values higher than their corresponding Clarke values. Based on the results obtained, it can be concluded that the examined ashes are approximately as harmful to the environment as ashes from other lignite used to generate electricity. Moreover, the increased amount of CaCO3 in the MPLS-1 is beneficial in the process of natural desulphurization.

PL

W ostatnich latach około jednej trzeciej polskiej energii elektrycznej pochodzi z węgla brunatnego, który jest spalany w wielkich elektrowniach. Powoduje to produkcję popiołów (żużla paleniskowego i popiołu lotnego) w łącznej ilości wyrażonej w milionach ton (Mt). Blisko 11% wag. popiołu produkowanego przez polską energetykę opartą na węglu brunatnym pochodzi z węgla wydobywanego przez Kopalnię Węgla Brunatnego Konin. Oczywiście, popiół jest składnikiem niepożądanym w węglu z wielu względów. Część popiołu może przedostać się do atmosfery, a pozostałą część należy poddać utylizacji, co jest kosztowne i często szkodliwe dla środowiska naturalnego. Stąd badania geochemiczne tych popiołów wydają się celowe i dlatego są coraz częściej przeprowadzane. Badane w tej pracy uśrednione próbki węgla reprezentują cały profil pierwszego środkowopolskiego pokładu węglowego (MPLS-1) eksploatowanego w odkrywkach: Jóźwin IIB, Drzewce i Tomisławice. Te próbki zostały najpierw utlenione/spalone w temperaturze: 100, 850 i 950°C. Następnie został określony ich skład chemiczny (tlenki i pierwiastki śladowe) według normy ASTM D6349-13. Badane popioły cechują się dominacją SiO2 i CaO, zaś w składzie pierwiastków śladowych przeważają: Ba, Sr i Cu. Natomiast wśród pierwiastków szkodliwych najważniejszy jest Pb. Wreszcie, tylko kilka z analizowanych pierwiastków (Ba, Cu, Pb, Sb) osiąga wartości wyższe niż wartości odpowiednich klarków. Na podstawie uzyskanych wyników można stwierdzić, że badane popioły są w przybliżeniu tak samo szkodliwe dla środowiska jak popioły z innych węgli brunatnych używanych do wytwarzania energii elektrycznej, a zwiększona ilość CaCO3 jest też korzystna w procesie naturalnego odsiarczania.

10

Vegetation response to environmental changes based on palynological research on the Middle Miocene lignite at the Jóźwin IIB open-cast mine (Konin region, central Poland)

63%

Słodkowska B. , Widera M.

Annales Societatis Geologorum Poloniae

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2021

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tom Vol. 91, No. 2

149--166

EN

Palynological research was performed on the first Mid-Polish lignite seam (MPLS-1) at the Jóźwin IIB open-cast mine. The extremely rich pollen assemblages allowed investigation of the development of phytogenic sedimentation and the succession of plant communities. The vegetation cover, representing peat accumulation and adjacent areas, was reconstructed in the homogeneous lignite seam. Despite the lack of clear macroscopic differences in the lignite lithology and a similar floristic composition, a similar succession of plant communities was observed in three repetitions in the profile. The plant communities described were grouped into five cycles. Changes in the succession resulted mainly from oscillations of the groundwater level. On the basis of the vegetation composition, the climatic conditions predominant during the peat-forming sedimentation were reconstructed. Climate changes are most precisely recorded in the mixed mesophilous forest community. Its floristic composition shows that the climate was warm-temperate and humid at that time. The lower part of the profile contains more taxa with high thermal requirements: Araliaceae, Mastixiaceae, Anacardiaceae, Hammamelidaceae, Cornaceae, Symplocaceae, Ilex, Itea, Engelhardia, etc. It is related to the Middle Miocene Climatic Optimum (MMCO). In the upper part of the profile, the vegetation composition reflects the beginning of a cooling trend. This is indicated by the reduced number of highly thermophilous taxa and the decreased taxonomic diversity of forest communities. The changing climatic and environmental conditions interrupted peat-bog sedimentation and caused termination of the development of thicker lignite seams.

11

The geology of the deepest Cenozoic lignite-rich grabens in Poland with particular reference to their lithostratigraphy: a comparative study

51%

Widera M. , Klęsk J. , Urbański P.

Geology, Geophysics and Environment

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2024

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tom Vol. 50, no. 2

131--143

EN

The thickest lignite seams in Poland are located in tectonic depressions such as the Kleszczów, Złoczew, and Lubstów grabens, as well as the Zittau (Żytawa) Basin. Their depth ranges from 220 m to 550 m, while the maximum lignite thickness ranges from approximately 90 m to over 250 m. The areas selected for this study include two Miocene lignite seams that have been exploited or prepared for mining, i.e. the third Ścinawa lignite seam (ŚLS-3) and the second Lusatian lignite seam (LLS-2). Currently, more than 95% of the Polish lignite production comes from the exploitation of these seams. Both lignite seams are accompanied by siliciclastic sediments that are lithologically very diverse. The lignite-rich grabens examined in this study form isolated structures and their individual geology is complex. Hence, apart from the Lubstów Graben, local lithostratigraphy is applied for each case, an approach that makes it difficult to compare the lithological units and their stratigraphic position with the Paleogene and Neogene lithostratigraphy used for the Polish Lowlands area. Therefore, it seems appropriate to present an outline of the geology of the Polish regions bearing most of the lignite seams, including a brief overview of their lithological and palaeotectonic characteristics. However, it is first necessary to clarify and compare the lithostratigraphy of the Cenozoic sediments that fill the studied grabens.

12

New insights into the genesis of the “Poznań clays” – upper neogene of Poland

51%

Maciaszek P. , Chomiak L. , Urbański P. , Widera M.

Civil and Environmental Engineering Reports

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2020

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tom Vol. 30, no. 1

18--32

EN

The present study focuses on the upper Neogene deposits, called the “Poznań Clays”, that cover more than 75,000 km2 of Poland. They are situated between the first midPolish lignite seam and the glaciogenic deposits of the Pleistocene age. Lithostratigraphically, the “Poznań Clays” belong to the uppermost portion of the lignite-bearing Grey Clays Member and the whole Wielkopolska Member (Poznań Formation). The examined fine-grained sediments include mud-rich floodplain deposits with palaeosol remnants and large sandy-muddy or muddy palaeochannel bodies. Therefore, taking into account facies analysis, cross-sectional geometry, and the planform of the palaeochannels, it can be stated that the “Poznań Clays” formed in the environment of a late Neogene anastomosing river.

13

Ancient and modern anastomosing rivers: insights from sedimentological and geomorphological case studies of the Triassic, Neogene and Holocene of Poland

51%

Kędzior A. , Widera M. , Zieliński T.

Geological Quarterly

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2021

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tom Vol. 65, No. 4

art. no. 54

EN

We review the three regional anastomosing fluvial systems, both ancient and modern. The dinosaur-bearing upper Triassic succession in Krasiejów (S Poland) is composed of siltstones and claystones that are divided into three facies associations. One of the fluvial associations is characterized by features typical of a low-energy anastomosing river system in a tropical semiarid climate, interpreted as the result of accumulation in deep, wide and low-sinuosity palaeochannels with pronounced vertical accretion. Deposition from suspension predominated in flows of very low stream power. The upper Neogene muddy succession in a tectonically active area (Kleczew Graben, central Poland) includes a great number of fluvial palaeochannels filled with sand and/or mud. These ribbon-shaped fluvial bodies are deep and wide, and represent channels showing very lim ited lateral migration. They were filled mostly under low-energy condi tions, and their mapped course shows an “anabranching” pattern in plan view. The palaeochannels are transitional from sand- to mud-dominated. The Holocene upper Narew River (NE Poland) represents a modern anastomosing fluvial system. The interconnected channels form an anabranching pattern. The channels are straight to slightly sinuous, relatively deep and wide. Interchannel, low-lying “islands” are covered by peat-forming plants. Despite the low stream power, in-channel deposition is dominated by sand transported as bedload. The channel banks are stabilised by vegetation, which effectively prevents their lateral migration.

14

The interpretative significance of ripple-derived sedimentary structures within an upper Neogene fluvial succession of central Poland

51%

Maciaszek P. , Chomiak L. , Wachocki R. , Widera M.

Geologos

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2019

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tom Vol. 25, No. 1

1--13

EN

Sedimentary structures discussed in the present study are genetically linked to ripples that consist of pure sand or alternating sand and mud layers. All types of ripple-related structures, such as climbing-ripple cross-lamination and heterolithic bedding, i.e., flaser, wavy and lenticular (nodular), have been identified for the first time in fluvial strata that have been characterised previously as commonly massive. These small-scale bedforms, produced by migrating ripples, have been documented in a fluvial channel of late Neogene age in central Poland. The abundance and co-occurrence of the structures discussed and their spatial distribution provide evidence of their formation under very low-energy conditions, when flow velocity changed markedly, but was often significantly less than 0.5 m/s. Therefore, these ripple-derived sedimentary structures are here recognised as typical of channel fills of an anastomosing river.

15

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

51%

Chomiak L. , Urbański P. , Widera M.

Przegląd Geologiczny

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2020

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tom 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.

16

Paleogene-Neogene tectonic evolution of the lignite-rich Szamotuły Graben

51%

Widera M. , Stawikowski W. , Uścinowicz G.

Acta Geologica Polonica

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2019

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tom Vol. 69, no. 3

387--401

EN

The Szamotuły Graben covers the southernmost part of the Permo-Mesozoic Poznań–Szamotuły Fault Zone. Along this regional discontinuity there are several salt structures, including the Szamotuły diapir, over which an extensional graben formed in the Paleogene and Neogene. The graben is located north of Poznań in central-western Poland, and is NW–SE-trending, ~20 km long, 3–5.5 km wide, and up to 160 m deep. It is filled with Lower Oligocene and Neogene sediments, including relatively thick lignite seams. Data from boreholes allow the assignment of the graben-fill sediments to appropriate lithostratigraphic units. Furthermore, analysis of changes in the thickness of these units provides evidence for periods of accelerated graben subsidence or uplift relative to its flanks. As a result, two distinct stages of tectonic subsidence and one inversion in the Paleogene–Neogene evolution of the Szamotuły Graben have been distinguished. Thus, relatively significant subsidence occurred in the Early Oligocene and the middle Early–earliest Mid-Miocene, while slight inversion took place in the middle part of the Mid-Miocene.

17

Four in one : a new crevasse-splay complex in the middle Miocene of central Poland

51%

Widera M. , Dziamara M. , Klęsk J. , Wachocki R.

Annales Societatis Geologorum Poloniae

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2024

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tom Vol. 94, No. 1

1--18

EN

This article focuses on a newly identified set of crevasse splays in the lignite-bearing Miocene of Poland. The sand bodies studied are situated within the First Mid-Polish Lignite Seam (MPLS-1) in the Tomisławice opencast mine, located near Konin in central Poland. The sand bodies form an alluvial complex of four superposed crevasse splays, separated by lignite layers, 0.1–0.8 m thick. They are considered to be overbank lateral splays, emplaced laterally by a fluvial channel, rather than its terminal splays. Their combined thickness reaches ~5 m, their length is <0.6 km and width <0.4 km, and their total area is ~0.1 km2. Nearly half of the sediments examined are subaerial deposits, while the rest are typical of crevasse-splay microdeltas, accumulated in a floodplain subaqueous environment. The sand bodies with local clay lenses are both underlain and overlain by, as well as interbedded with a range of lignite lithotypes, representing various sub-environments of a mid-Miocene mire (backswamp) realm. The estimated time span for the formation of the entire crevasse-splay complex, recording four short-term floods, is at least 48 kyr. The crevasse-splay complex is one of the best developed in lignite/coal successions worldwide. However, it poses a major technical obstacle to mining activity in the Konin Lignite Mine.

18

Palaeoenvironment of the middle Miocene wetlands at Drzewce, Konin region, central Poland

51%

Worobiec E. , Widera M. , Worobiec G.

Annales Societatis Geologorum Poloniae

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2022

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tom Vol. 92, No. 2

201--218

EN

Palynological analysis of the 1st mid-Polish lignite seam (MPLS-1) of the Drzewce deposit (Konin region, central Poland) was used as the data source for palaeoenvironmental and palaeoclimatic interpretations. Lignites of the 1st group developed in the middle Miocene, during and shortly after the last peak of the Mid-Miocene Climatic Optimum, over a large area of Poland, and they are the youngest of the main Neogene lignite seams in Poland. In the Konin region, these lignites have a relatively significant thickness (up to 20 m) and therefore they are (or were in the past) exploited in several open-pit mines. A total of 36 palynological samples from the 6.3-m-thick seam of the Drzewce opencast mine was studied in detail. Palynological analysis of the lignite seam indicates that the area was overgrown by palustrine wetland communities, similar in composition to modern pocosins. The most characteristic elements of them were shrubs in the Ericaceae family. The climate at that time was warm temperate and humid. The estimated mean annual temperature (MAT) for the lignite seam at Drzewce is 15.7–17.8 °C. Comparison with other palynofloras from the MPLS-1 shows that the climate during the formation of the group of seams was more or less homogenous across the entire Polish Lowlands. Sedimentological data and results of palynological studies (including NPPs) at Drzewce indicate that the palaeomires were relatively distant from the channels of the river system in the Konin Basin. The fossil fungal assemblage indicates dense vegetation on damp, swampy soils and the presence of small, shallow-water bodies, with a variable water level or even periodic reservoirs, existing only during the wet season or after floods. In small, flooded depressions, such as the pools in bogs, filamentous green algae occurred. The presence of zygospores of the desmids Desmidiaceaesporites cosmarioformis most probably indicates relatively nutrient-poor (ombrotrophic) conditions. Fluctuations in the frequency of individual plant taxa (including Sequoia and Sciadopitys) are likely to reflect changes in water level and trophic conditions.

19

Geological and palaeogeographical peculiarities of the Adamów Graben area, central Poland

51%

Widera M. , Dzieduszyńska D. , Petera-Zganiacz J.

Geologos

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2022

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tom Vol. 28, No. 1

1--17

EN

From a geological and palaeogeographical point of view, the area of the Adamów Graben in the vicinity of Turek ranks amongst the best known in central Poland, with several opencast mines located here where lignite was exploited for 57 years. These large-surface exposures provide a good opportunity for detailed geological studies of strata of Late Cretaceous to Holocene age. However, the present research focuses mainly on those deposits, forms and structures that have been most thoroughly examined and are best exposed. These are Cretaceous marls and gaizes, Paleogene ‘blue clays’ and the ‘Koźmin Gravels’, Neogene sandstones, as well as the Quaternary glacial ‘Lake Koźmin’, involutions and ‘Koźmin Las’. Some of these, e.g., the ‘Koźmin Gravels’ and ‘Koźmin Las’, are not known from other Polish territories. Furthermore, results obtained by the authors over a period of nearly 30 years also include data on palaeogeographical changes across some Cenozoic intervals, especially during the early Oligocene and late Weichselian.

20

Polish lignite resources, mining and energy industries - what is next?

51%

Widera M. , Urbański P. , Mazurek S. , Naworyta W.

Gospodarka Surowcami Mineralnymi

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2024

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tom T. 40, z. 2

5--28

EN

Poland is among the top ten countries in the world in terms of lignite resources (including reserves). With respect to lignite mining, its position is even higher at sixth in the world, fourth in Europe and second in the European Union (EU). The role of lignite in the Polish energy mix is crucial because ~27% of electricity was generated in lignite-fired power plants in 2022. However, there are countries in Europe where the dependence on lignite is much greater and currently in the range of 40-96%. Both the national and EU climate energy policy assumes the abandonment of lignite as a source of ‘dirty’ electricity within the next two decades. This ambitious goal is achievable but it may be threatened by the geopolitical situation. However, after 2040-2044, a large number of lignite deposits will remain in Poland. The deposits are well recognized and the detailed geology is well documented, with the estimated reserves intended for exploitation amounting to 5.8 Gt. These deposits, like the five which are currently mined, are stratigraphically diverse and characterized by a complex geology, representing different genetic types. In the context of a coal-free energy policy in the EU, the problem of the legal protection of lignite deposits remains. Thus, the question arises of what is next for Polish lignite deposits. They may be managed in the coming decades by using improved unconventional methods, such as in situ or ex situ gasification. Lignite deposits will constitute a strategic reserve in the event of a deep energy crisis caused by an unstable geopolitical situation. Finally, we suggest the urgent introduction of more precise legal changes that would protect at least part of the lignite resources in Poland for future generations.

PL

Polska znajduje się w pierwszej dziesiątce krajów na świecie pod względem zasobów i rezerw węgla brunatnego. Pod względem wydobycia węgla brunatnego jej pozycja jest jeszcze wyższa, tj. szósta na świecie, czwarta w Europie i druga w Unii Europejskiej (UE). Rola węgla brunatnego w polskim miksie energetycznym jest kluczowa, gdyż w 2022 roku w elektrowniach nim opalanych wytworzono ~27% energii elektrycznej. Zarówno krajowa, jak i unijna polityka klimatyczno-energetyczna zakłada w ciągu najbliższych dwóch dekad odejście od węgla brunatnego jako źródła „brudnej” energii elektrycznej. Ten ambitny cel jest możliwy do osiągnięcia, jednak może mu zagrozić sytuacja geopolityczna. Z drugiej strony, po latach 2040-2044, w Polsce pozostanie duża liczba złóż węgla brunatnego. Złoża są dobrze rozpoznane, szczegółowa budowa geologiczna dobrze udokumentowana, a szacowane zasoby przeznaczone do eksploatacji wynoszą 5,8 Gt. Złoża te, podobnie jak pięć obecnie eksploatowanych, są zróżnicowane stratygraficznie, charakteryzują się złożoną geologią oraz reprezentującą różne typy genetyczne. W kontekście bezwęglowej polityki energetycznej w UE pozostaje problem prawnej ochrony złóż węgla brunatnego. Rodzi się zatem pytanie: co dalej z polskimi złożami węgla brunatnego? Można je w nadchodzących dziesięcioleciach zagospodarować, stosując udoskonalone metody niekonwencjonalne, takie jak zgazowanie in situ lub ex situ. Złoża węgla brunatnego będą stanowić rezerwę strategiczną na wypadek głębokiego kryzysu energetycznego spowodowanego np. niestabilną sytuacją geopolityczną. Zatem sugerujemy pilne wprowadzenie bardziej precyzyjnych zmian prawnych, które chroniłyby przynajmniej część zasobów węgla brunatnego w Polsce dla przyszłych pokoleń.