The first mid-Polish lignite seam (MPLS-1), mined in the vicinity of Konin and Turek in central Poland, has been subjected to multi-directional studies. These allowed for the deciphering of the environmental conditions in which relatively thick peat deposits were formed in the Middle Miocene. Research into organic matter alone does not allow for a complete determination of the mire type and its evolution. Much valuable additional information on this subject can be provided by a sedimentological study of siliciclastic interbeddings contained within the lignite seam. Therefore, this paper presents the results of low-rank coal lithotypes and clastic facies analysis. MPLS-1 from the Adamów–Konin Basin shows that the use of these two research methods can give satisfactory results. The lithotype analysis showed that sedimentary sub-environments (mire types: fen/open water, bush moor and forest mires, both relatively wet and dry) changed both vertically and laterally. On the other hand, sedimentological analysis of the siliciclastic sediments provides indirect evidence that the Mid-Miocene mires in central Poland existed in the vicinity of river channels. Their waters repeatedly flooded the mires, interrupted their evolution, and significantly increased the ash yield of MPLS-1. Finally, the presented results are in agreement with those obtained from palynological research.

In the Lubusz region (western Poland), lignite was already mined in the first half of the 19th century. German exploitation of the lignite proceeded on an industrial scale and continued until the end of World War II. After the war, Poland took up excavations in this area, but exclusively at the Sieniawa Lignite Mine (SLM). This mine, the smallest in Poland, was state-owned for over half a century; since 2002 it has been a private company. Annual lignite production at SLM rarely exceeded 0.1-0.2 million tonnes (Mt), although, in recent years, it has increased significantly, reaching a record level of over 1 Mt. These mining achievements are particularly impressive within the context of the highly complex geological structure of the study area. For over 150 years, SLM has been exploiting one of the most glaciotectonically disturbed lignite seams in the world, first underground and later in opencast. This lignite belongs to the 2nd Lusatian group of seams, is of late Early-early Middle Miocene age, having formed under the conditions of the Miocene Climatic Optimum. The wetland vegetation (swamp forests and shrub bogs) in the warm, near-subtropical climate produced large amounts of peat, which ultimately led to lignite formation. Detritic lignite dominates (followed by xylodetritic lignite) and is characteristically weathered in its upper part, containing numerous traces of wildfires. Finally, despite the energy transformation, SLM has a chance to continue operating for at least several more decades, this being the longest amongst all Polish lignite mines.

Remains of microsclerotia morphologically corresponding to those of modern dark septate endophytic (DSE) fungi were found during palynological studies of some Oligocene and Miocene sites from Poland. Fossil microsclerotia, mostly represented by leaf-like morphotypes were morphologically diversified, but there was no possibility to match the fossil morphotypes with modern fungal DSE taxa forming microsclerotia in roots. Reliable fossils of microsclerotia of dark septate endophytic fungi date back to the Eocene and show continuous presence till recent times. They confirm the coexistence of dark septate endophytic fungi with plants at least from the beginning of the early Cenozoic. Pre-Cenozoic fossils of presumed DSE microsclerotia were considered doubtful. The presence of microsclerotia in continental deposits points to dense vegetation in the past, and in marine deposits, they indicate terrigenous flux that originated from coastal vegetation.

Around the town of Konin in central Poland, lignite deposits are exploited in opencast mines. Surface mining has enabled the discovery of many sediments and structures, both tectonic and sedimentary. However, the greatest research challenge appeared in the Tomis & lstrok;awice lignite opencast mine in 2022, when a so-called lignite-free zone was found during mining activity. Initially, due to limited data, its genesis was associated with syn- or post-depositional tectonics and peat-to-lignite compaction. In 2024, two deeper boreholes were drilled in which no lignite and tectonic denivelations of the Mesozoic bedrock were detected in the mentioned zone, meaning that the above hypotheses were disproved. Therefore, in this paper a new hypothesis was proposed for the creation of the aforementioned lignite-free zone crossing the Tomis & lstrok;awice lignite deposit - palaeochannel I - and as well as marking its NE border - palaeochannel II. The inclusion of data from a larger number of boreholes and the reinterpretation of the depositional architecture of the fills of the lignite-free zones indicate the palaeochannel avulsion of the late Neogene fluvial system. The palaeochannels are filled with fine-grained and multi-coloured Pozna & nacute; Clays. Unfortunately, they are mainly massive, and the poorly visible sedimentary structures are masked by post-depositional weathering processes. The palaeochannels were incised into the underlying lignite seam and sub-lignite sands during the initial stages of major floods and then filled by the accretion of heterolithics, mainly from suspension, during subsequent flood episodes. Rather than a tectonic/compactional origin, data are consistent with palaeochannel avulsion. Finally, the current paper is the first in Poland devoted exclusively to the effects of avulsion in the rock record.

The 80th anniversary (1945–2025) of the Konin Lignite Mine (KLM) invites some summaries of the mine’s characteristics. Therefore, the current study is devoted to rocks/sediments and tectonic or sedimentary structures that were observed and examined in lignite opencasts in the vicinity of the town of Konin. Some of them can be considered wonders and/ or curiosities of nature, some are unique, and others are quite common. Hence, they were generally defined as geological peculiarities in this article. In stratigraphic order they are sandstones, cleats, crevasse splays, palaeochannels and palaeosols. They represent various lithostratigraphic units (formations and members) of the Neogene of central Poland, while their age ranges from the Early Miocene to the earliest Pliocene. Among the listed objects, quartzite sandstones (situated below and between the lignite beds) and palaeosols in the Poznań Clays are very common, known from other lignite opencasts in Poland. In the case of cleats and crevasse splays occurring within the lignite seam exploited by the KLM, they are among the most numerous and best developed of all lignite-bearing formations in the world. On the other hand, the presence of palaeochannels in fine-grained sediments, constituting the overburden of the exploited lignite seam, provides additional and convincing evidence for the fluvial origin of the Poznań Clays.

The PoznanClays, de pos ited dur ing the late Neo gene, form one of the most fa mous lithological units in Po land, and the PoznanFor ma tion is a lithostratigraphic unit which in cludes these fine-grained de pos its. This for ma tion is di vided into the lower Grey Clay Mem ber (MPLS-1 - the first Mid-Pol ish lig nite seam and grey clays) and the up per Wielkopolska Mem ber (green and flame-col oured clays). Nev er the less, the PoznanClays com prise the up per most parts of the lower Grey Clay Mem ber and the en tire up per Wielkopolska Mem ber. This of ten causes con fu sion among re search ers who in cor rectly as sign the po si tion of the PoznanClays in the lithostratigraphic scheme of the Neo gene of the Pol ish Low lands. This also re sults in incorrect determination of the age of the PoznanClays, which in re al ity span the time in ter val be tween the late Mid dle Mio cene and the ear li est Early Plio cene. Such a range of mean ing, cov er ing two lithostratigraphic mem bers, im pacts the in ter pre ta tion of the or i gin of the PoznanClays. An ad di tional fac tor com pli cat ing the un der stand ing of the prob lem is the con nec tion be tween the col our of the PoznanClays and their strati graphic po si tion. The PoznanClays and the PoznanFor mation are often ambiguously understood, and these issues require clarification and discussion, as provided in this study.

Palynological analysis of samples taken from the lignite, exposed in the Ch & lstrok;apowo Cliff on the southern Baltic coast, allowed the reconstruction of the vegetation and palaeoclimate that predominated during the accumulation of the peat, from which the lignite was formed. In addition to pollen grains and spores, particular attention was given to non-pollen palynomorphs, such as algal, fungal and invertebrate micro-remains (Cladocera) that enabled a more accurate reconstruction of the palaeoenvironment. The lignite belongs to the 2nd Lusatian seam, which is an important correlation level in Central Europe, dated to the latest Early Miocene to the early Middle Miocene. The textural and structural features of the lignite seam indicate that the depositional environment of the peat is loosely combined with the overbank zone of an anastomosing or meandering river system. The results of the palynological study show the presence of wetland vegetation, including shrub bogs (most similar in their composition to modern pocosins, growing between river channels) and riparian forests, growing on periodically flooded areas and mesophilous vegetation, occurring in the vicinity. The composition of the palynoflora, including the thermophilic taxa, such as Sapotaceae and Meliaceae, indicates that the climate was warm, close to subtropical, with a mean annual temperature range of 15.7-17.8 degrees C.

The Konin region is widely considered to be the cradle of lignite mining in Poland, having probably exploited as early as the 12th century on the outskirts of the present-day town of Konin. However, not until the first half of the 20th century were lignite-rich deposits discovered. In turn, industrial lignite mining in this region was initiated by the Germans during the Second World War and has been continued by Polish crews since 1945. Thus, 80 years of Polish history of Konin Lignite Mine (KLM) will be celebrated in 2025. Over eight decades, KLM has launched several opencasts, only one of which remains at the start of 2025. During this time, hundreds of millions of tonnes of lignite (646.1 million tonnes) have been mined. In order to extract such large quantities of lignite, billions of cubic metres of water (6.14 billion m3) and overburden (3.59 billion m3) had to be pumped out and removed, respectively. In this way, the natural environment in the vicinity of Konin was strongly transformed geologically, hydrogeologically and geomorphologically. The results of these changes include numerous anthropogenic hills (external dumps) and water reservoirs (mining lakes). They, along with other post-mining areas, have been subject to reclamation since at least the 1970s. KLM is carrying out reclamation works in the following directions: water, forest, agricultural, recreational, etc. It is currently expected that lignite mining in the Konin region will most likely end in 2026–2027.

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 Tomislawice open-cast 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 similar to 5 m, their length is <0.6 km and width <0.4 km, and their total area is similar to 0.1 km(2). 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.

This article is devoted exclusively to three iron minerals that have a decisive influence on the colour of the ‘Poznań Clays’. These are hematite, goethite, and jarosite. Their presence gives the ‘Poznań Clays’, which are the most common and best known Neogene lithostratigraphic unit in the Polish Lowlands, characteristic ‘warm’ colours ranging from yellow through orange to dark red. The presented results were mainly obtained using powder X-ray diffraction and 57Fe Mössbauer spectroscopy.

This article briefly focuses on comparing geological information shown in a cross-section with field data. An example from the Tomisławice opencast mine, where the first Mid-Polish lignite seam (MPLS-1) is currently exploited for electricity production, is used where two sites present large and even surprising differences. In the first case, they are due to technical reasons, i.e., wet drilling. The second case is most likely caused by the compaction of peat during its transformation into lignite. The obtained results clearly indicate that the actual geological structure observed in the field may differ significantly from that which is interpreted on the geological cross-sections based on borehole data.

Understanding the Cenozoic tectonic evolution of grabens rich in lignite is important in the context of the accumulation of ~40–650 m of peat, as well as the exploitation of later formed lignite seams with a thickness of ~20–250 m. Six such areas were selected for a detailed palaeotectonic analysis: the Gostyń, Szamotuły, Legnica, Zittau, Lubstów, and Kleszczów grabens. During the analysis, borehole data were used, taking into account the compaction of peat at the transition to lignite, in order to reconstruct the magnitude of the total subsidence. This made it possible to distinguish between regional (covering areas also outside the grabens) and local (occurring only in the grabens) tectonic movements, and among the latter, tectonic and compactional subsidence. The hypothetical palaeosurface of the mires was reconstructed based on the lignite decompaction. As a result, it was possible to determine whether the examined peat/lignite seams underwent post-depositional uplift and/or subsidence. Between one (Gostyń Graben) and four (Zittau Basin and Kleszczów Graben) stages of tectonic subsidence were distinguished in the studied lignite-bearing areas. In the case of the Zittau Basin, as well as the Lubstów and Kleszczów grabens, post-depositional stages of tectonic uplift were also indicated. Like the boundaries of lithostratigraphic units, the successive stages of the Cenozoic tectonic development of the examined grabens are diachronic.

This article is devoted exclusively to three iron minerals that have a decisive influence on the colour of the 'Pozna & nacute; Clays'. These are hematite, goethite, and jarosite. Their presence gives the 'Pozna & nacute; Clays', which are the most common and best known Neogene lithostratigraphic unit in the Polish Lowlands, characteristic 'warm' colours ranging from yellow through orange to dark red. The presented results were mainly obtained using powder X- ray diffraction and 57Fe M & ouml;ssbauer spectroscopy.

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.

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. Z arówno 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. Z łoża są dobrze rozpoznane, szczegółowa budowa geologiczna dobrze udokumentowana, a szacowane zasoby przeznaczone do eksploatacji wynoszą 5,8 Gt. Z łoża 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. Z łoża węgla brunatnego będą stanowić rezerwę strategiczną na wypadek głębokiego kryzysu energetycznego spowodowanego np. niestabilną sytuacją geopolityczną. Z atem sugerujemy pilne wprowadzenie bardziej precyzyjnych zmian prawnych, które chroniłyby przynajmniej część zasobów węgla brunatnego w Polsce dla przyszłych pokoleń.

A fungal palynomorph corresponding to the fossil-species Lirasporis intergranifer R. Potonie & S.C.D. Sah, from the Middle Miocene lignite mine in Tomislawice (central Poland), is considered as the new combination Cancellidium intergraniferum (R. Potonie & S.C.D. Sah) G. Worobiec & E. Worobiec, comb. nov. The fossil-genus Lirasporis is treated as a synonym of the modern genus Cancellidium Tubaki. Cancellidium intergraniferum from the Miocene of Poland represents the first fossil record of Cancellidium outside Asia, the first record of this genus from Europe, and the northernmost known fossil occurrence of Cancellidium. Living representatives of Cancellidium seem to prefer warm and humid climates and, being aero-aquatic hyphomycetes, are usually associated with decaying woody remains in aquatic environments. A similar ecology is suggested for the fossil C. intergraniferum, which could be a reliable fungal non-pollen palynomorph proxy for palaeoclimatic and palaeoenvironmental reconstructions.

This opinion study is devoted to the role of lignite in the Polish energy sector in recent decades, i.e., after the collapse of communism in 1989. Lignite is the primary source of electricity in Poland, second only to hard coal. More than 25-35% of Polish electricity was generated by lignite-fired power plants in 1990-2022. To meet the needs of the energy industry, 46-70 Mt of lignite was mined annually in that period. Hence, Poland was, and still is, one of the world leaders in lignite production. Despite the ongoing transition of the Polish energy sector, changes occur very slowly due to political, economic, environmental and social reasons. In the years 2021-2022, the downward trend in lignite mining, influenced mainly by the COVID-19 pandemic, was reversed by the war in Ukraine. Fortunately, there is now a great opportunity to accelerate the energy transition in Poland because of domestic political changes at the end of 2023. Nevertheless, complete independence from coal, including lignite, will not take place within the next 10-25 years, i.e., before nuclear power plants are built and the share of renewables in Poland's energy mix increases by at least several times.

This article briefly focuses on comparing geological information shown in a cross-section with field data. An example from the Tomis & lstrok;awice opencast mine, where the first Mid-Polish lignite seam (MPLS-1) is currently exploited for electricity production, is used where two sites present large and even surprising differences. In the first case, they are due to technical reasons, i.e., wet drilling. The second case is most likely caused by the compaction of peat during its transformation into lignite. The obtained results clearly indicate that the actual geological structure observed in the field may differ significantly from that which is interpreted on the geological cross-sections based on borehole data