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The first microfossil record of ichthyofauna from the Naujoji Akmenė Formation (Lopingian), Karpėnai Quarry, northern Lithuania

100%

Dankina D. , Chahud A. , Radzevičius S. , Spiridonov A.

Geological Quarterly

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2017

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tom Vol. 61, No. 3

602--610

EN

The assemblage of rare fish microremains of chondrichthyans and actinopterygians from Upper Permian deposits in Karpénai Quarry in northern Lithuania is described in detail for the first time. The deposits are characterized as reflecting a rapid phase of deposition of the Zechstein Limestone, interpreted as on a shallow shelf above storm-wave base in a proximal part of the Polish-Lithuanian Zechstein Basin. The actinopterygian microremains are represented by various teeth and a few scales from mostly palaeonisciforms and pycnodontiforms. The chondrichthyans are represented by various eusela- chian-type scales and a tooth of ?Helodus sp. The low abundance and low species diversity of the fossil assemblages studied may be due to arid palaeoenvironments that caused locally restricted conditions at this palaeogeographical location.

2

Controls on basal Zechstein (Wuchiapingian) evaporite deposition in SW Poland

86%

Dyjaczyński K. , Peryt T. M.

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tom Vol. 58, No. 3

485--502

EN

The development of basal Zechstein (Wuchiapingian) strata inSW Polandindicates the existence of a diversified relief inherited after the flooding of the pre-existing depression by the transgressing Zechstein sea. The deeper parts of the basin were the place of development of thin basinal Zechstein Limestone showing sedimentary condensation manifested by bored and encrusted grains and thick evaporites (mostly halite), and in shallow parts Zechstein Limestone reefs followed by thinner evaporite sequences (dominated by anhydrite) occur. The analysis of 3D seismic sections showed that instead of three conventionally recognized evaporite units of stratigraphic potential in the PZ1 cycle, five units occur (from the base to the top: Lower Anhydrite, Lower Oldest Halite, Middle Anhydrite, Upper Oldest Halite, Upper Anhydrite). In a particular place their number may vary from two (Lower Anhydrite at the base of the PZ1 cycle and Upper Anhydrite at the top of the PZ1 cycle) to five. There are two complexes of Lower Anhydrite occurring throughout the platform and basinal zones showing deepening-upward (transgressive) trend. The halite sedimentation in the deepest parts of salt basins began shortly after the deposition of the upper Lower Anhydrite complex while in the sulphate platform areas the sulphate deposition lasted still for a long time. The Lower Oldest Halite deposits occur in the depressions. Between the halite basins, anhydrite platforms occur, and the thickness of anhydrite platform deposits is smaller than it is observed in salt basins. The Upper Oldest Halite in turn is recorded above the anhydrite platform. The two halite units represent different phases of development of halite basins. The Lower Oldest Halite basins are related to the pre-Zechstein depressions, although in some cases their syndepositional subsidence was controlled by reactivation, during the deposition of basal Zechstein strata, of former faults. In turn, the Upper Oldest Halite basins used the accommodation space created due to anhydritization of the Lower Anhydrite deposits composed originally of selenitic gypsum. The 3D seismics evidences that the PZ1 evaporites inSW Polandhave been deposited in far more complex and dynamic system than it was assumed before.

3

Hydrocarbons in the Upper Permian PZ1– PZ2 cycles of the Kłodawa Salt Structure, central Poland

86%

Wolny Ł. , Czechowski F. , Burliga S. , Raczyński P. , Hojniak M.

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2014

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tom Vol. 84, No. 4

363--374

EN

Organic geochemical studies were carried out on the sulphate–shale–carbonate series, representing the upper PZ1 and lower PZ2 sections of the Zechstein cycles in the Kłodawa Salt Structure, located in the central part of the Zechstein Basin, in Poland. Hydrocarbons extracted from the Na1 and Na2 rock salts, the A1g and A2 anhydrites, the Ca2 dolomitic anhydrite and the T2 shale-carbonate rocks were analysed by gas chromatography mass spectrometry (GC-MS). Homological series of the n-alkanes and chained isoprenes indicate the algal nature of the organic matter with the characteristic chemiistry of type II kerogen deposited under anoxic conditions. The molecular composition of other biomarkers (n-alkylbenzenes, steranes) as well as phenenthrene and dibenzothiophene and their methyl derivatives revealed the highest maturity of the hydrocarbons (level of advanced stage of the oil-window zone) in the upper part of the Stinking Shale. In the adjacent beds, a gradual decrease in the maturity of the hydrocarbons was observed both upwards and downwards in the stratigraphic sequence. The main source rock of the hydrocarbons is represented by the Stinking Shale deposits. The observed trend of vertical variation in maturity through the rock profile is explained as resulting from the continuous vertical migration of hydrocarbons, expelled during maturation from the Stinking Shale rocks into the underlying and overlying strata.

4

Hydrogen sulphide (H2S) migration in groundwater of the Zechstein strata in the Legnica-Głogów Copper Basin and its vicinity, SW Poland

86%

Duda R. , Bilkiewicz E. , Becker R.

Geological Quarterly

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2023

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tom Vol. 67, No. 3

art. no. 39

EN

Hydrogen sulphide (H2S) occurs in groundwater in various lithostratigraphic units of the Zechstein Basin in the Legnica-Głogów Copper Basin (SW Poland). This region is located in the Fore-Sudetic Monocline within which, several tens of kilometres NE of the study area, at greater depths, natural gas fields with hydrogen sulphide (H2S) occur. The Main Dolomite (Ca2), in which H2S-containing natural gas has accumulated, is younger than the Zechstein Limestone (Ca1), which is actively mined. The Ca2 and Ca1 formations are separated by a thick anhydrite succession including a wedge-shaped salt body. Hydrochemical analyses of 18 groundwater samples taken from different horizons within the Zechstein strata showed spatial variability of H2S and chloride concentrations. A conceptual model of groundwater flow with dissolved H2S in the Zechstein formations was developed. H2S migration is associated with groundwater flow between the Ca2 and Ca1 aquifers through fissures in the anhydrite strata that separate them. Hydraulic contact through fissures in the anhydrite layers is the result of long-term exploitation of the underground copper deposit. Groundwater flow between the layers is influenced by a large change in the piezometric pressure of the groundwater in the depression cone caused by mining drainage.

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Late Permian ichthyofauna from the North-Sudetic Basin, SW Poland

44%

Dankina D. , Spiridonov A. , Raczynski P. , Radzevicius S.

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tom 66

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nr 3