Polish Basin Research Articles

Depositional architecture of the Upper Cretaceous succession in central Poland (Grudziądz-Polik area) based on regional seismic data

Interpretation of the regional high-resolution seismic data of the PolandSPANTM survey in the Grudziądz-Polik area revealed a new depositional architecture of the Upper Cretaceous succession that differs substantially from the previously assumed layer-cake model, commonly applied to Permian-Mesozoic sequences. A previously unrecognized regional unconformity, dividing the Upper Cretaceous succession into two units characterized by very different internal geometries, was identified and mapped. The lower unit, with a generally layer-cake internal pattern, is overlain by an upper unit composed of a regionally low-angle succession that pinches out toward the south. This newly revealed regional pattern remained unrecognized in previous regional compilations based on borehole data, which suggested that a layer-cake depositional architecture prevailed throughout the entire Upper Cretaceous. This new image of Upper Cretaceous depositional patterns has far-reaching consequences for understanding of the evolution of the Polish Basin in the Late Cretaceous, including its subsidence and burial history, deposition, and tectonic development. A re-evaluation of the chronostratigraphy of the Upper Cretaceous of the Polish Basin is needed to temporally constrain the succession of sedimentary and tectonic events revealed here.

Palaeoclimatic changes and inter-regional correlations in the Jurassic/Cretaceous boundary interval of the Polish Basin: portable XRF and magnetic susceptibility study

Palaeoclimatic changes and inter-regional correlations in the Jurassic/Cretaceous boundary interval of the Polish Basin: portable XRF and magnetic susceptibility study

Jurassic planktic foraminifera from the Polish Basin

Abstract. Jurassic (Bathonian–Oxfordian) planktic foraminifera from the epicontinental strata of the Polish Basin have been investigated. The palaeoecology, palaeobiogeography, and biostratigraphical potential of the recorded taxa are discussed. Four species are recorded: Conoglobigerina helvetojurassica (Haeusler, 1881), Globuligerina balakhmatovae (Morozova, 1961), G. bathoniana (Pazdrowa, 1969), and G. oxfordiana (Grigelis, 1958). This assemblage is probably the most diverse of those described to date from the epicontinental areas of Europe. The recorded taxa are thought to represent three different ecological morphotypes. The clear relationship between transgressive–regressive facies and the palaeobiogeography of the recorded planktic foraminifera indicates a morphotype-related depth–distribution pattern in which small, simple, globular-chambered morphotypes occupied shallow waters whereas slightly larger, more complex forms, or those with hemispherical chambers, inhabited deeper and more open-water environments.

Assessment of serpulid-hydroid association through the Jurassic: A case study from the Polish Basin.

The coexistence of sessile, tube-dwelling polychaetes (serpulids) and hydroids, has been investigated. Serpulid tubes bearing traces after hydroids are derived from different stratigraphic intervals spanning the Middle and Upper Jurassic, the rocks of which represent the diverse paleoenvironments of the Polish Basin. Although fossil colonial hydroids classified under the species Protulophila gestroi are a commonly occurring symbiont of these polychaetes during the Late Cretaceous and Cenozoic, they seem to be significantly less frequent during the Jurassic and limited to specific paleoenvironments. The hydroids described here are represented by traces after a thin stolonal network with elongated polyp chambers that open to the outer polychaete tube’s surface with small, more or less subcircular apertures. Small chimney-like bulges around openings are an effect of the incorporation of the organism by in vivo embedment (bioclaustration) within the outer layers of the calcareous tube of the serpulid host. Considering the rich collection of well-preserved serpulid tubes (>3000 specimens), the frequency of bioclaustrated hydroids is very low, with an infestation percentage of only 0.6% (20 cases). It has been noticed that only specimens of the genus Propomatoceros from the Upper Bajocian, Lower Bathonian, Middle Bathonian, and Callovian have been found infested. However, the majority of bioclaustrated hydroids (17 cases) have been recorded in the Middle Bathonian serpulid species Propomatoceros lumbricalis coming from a single sampled site. Representatives of other genera are not affected, which is congruent with previous reports indicating that Protulophila gestroi was strongly selective in the choice of its host. A presumably commensal relationship is compared with the recent symbiosis between the hydroids of the genus Proboscidactyla and certain genera of sabellid polychaetes.

Toarcian climate and carbon cycle perturbations – its impact on sea-level changes, enhanced mobilization and oxidation of fossil organic matter

Organic geochemistry and palynology reveal major organofacies changes in the marginal marine Polish Basin during the early Toarcian linked to changes in environmental conditions. Increasing water salinity and enhanced biomass contributions from phytoplankton, adopted to brackish conditions, attest to periodic marine ingressions into the paralic, hyposaline Polish Basin. Marine ingressions occurred upon reoccurring sea level rises concomitant with i) the Pliensbachian-Toarcian boundary carbon isotope excursion (Pl-Toa-CIE) and ii) the stepped Toarcian carbon isotope excursion (Toa-CIE), the latter marking the Toarcian Oceanic Anoxic Event (Toa-OAE). Strata with marine influences indicate an intermittent connection of the Polish Basin with the Tethys and attest to a close correlation between regional shoreline progradation and evolution of global climate and sea-level. Organic geochemistry indicated the link between sea level fluctuations and the Toa-CIEs, although in some areas of the Polish Basin the sea level rise was balanced by massively increased sediment delivery, caused by enhanced hydrological cycling that lead to intensified weathering and erosion in the hinterland. Enhanced hydrological cycling further led to the remobilization of organic matter of pre-Toarcian age. This points to erosion of older organic-rich rocks containing significant abundances of marine and terrestrial organic matter that was partly oxidized and re-deposited along with autochthonous Toarcian organic matter. Provenance areas identified point to two main sources, most likely Carboniferous terrestrial/paralic and Ordovician/Silurian marine sediments. Fossil organic matter should be considered as additional source in Toarcian carbon cycling, particularly in times of enhanced hydrological cycling, erosion and weathering. Remobilization of sedimentary fossil carbon has not been hitherto considered as a carbon source during the Toa-OAE.

Polycyclic aromatic hydrocarbons in Middle Jurassic sediments of the Polish Basin provide evidence for high-temperature palaeo-wildfires

The distributions and concentrations of polycyclic aromatic hydrocarbons (PAHs) and plant-derived aromatic biomarkers were analysed in Middle Jurassic strata from central Poland. These compounds were abundant in all samples indicating the occurrence of specific palaeoflora families and the intensity of palaeo-wildfires. Moreover, calculated fusinite reflectance values revealed that the temperature of Middle Jurassic wildfires may have exceeded 950 °C, consistent with high oxygen concentrations in the atmosphere during this period. The high content of charred organic matter has an influence on certain biomarker maturity indicators based on terrestrial organic matter such as C29 20S/(S + R). A new indicator was developed, benzo[ghi]perylene/(perylene + benzo[ghi]perylene), abbreviated as BgP/(Per + BgP, high values of which are characteristic of samples in which terrestrial organic matter is mostly charred. The use of this indicator is limited to immature organic matter, since perylene disappears when vitrinite reflectance is higher than 0.7 %Ro. Measurements of vitrinite reflectance indicated that Middle Jurassic organic matter with a reflectance value < 0.51 %Ro was immature or early-mature. Juxtaposition of the modified higher plant index (mHPI) calculated from mHPI = (retene + cadalene + ip-iHMN)/(retene + cadalene + ip-iHMN + 1,3,6,7-TeMN) and BgP/(Per + BgP) showed that samples from the central part of the Polish Basin contained more charred than unburnt terrestrial organic matter, as values of BgP/(Per + BgP) > 0.5 are correlated with lower mHPI values. This is evidence for the transport of wildfire products by rivers, wind, and/or sea currents over large distances. Tracers for conifers, non-vascular plants, and fungi were identified.

Fault-controlled Permian sedimentation in the central Polish Basin (Bydgoszcz–Szubin area) – Insights from well and seismic data

Fault-controlled Permian sedimentation in the central Polish Basin (Bydgoszcz–Szubin area) – Insights from well and seismic data

Analysis of Groundwater and Total Water Storage Changes in Poland Using GRACE Observations, In-situ Data, and Various Assimilation and Climate Models

The Gravity Recovery and Climate Experiment (GRACE) observations have provided global observations of total water storage (TWS) changes at monthly intervals for over 15 years, which can be useful for estimating changes in GWS after extracting other water storage components. In this study, we analyzed the TWS and groundwater storage (GWS) variations of the main Polish basins, the Vistula and the Odra, using GRACE observations, in-situ data, GLDAS (Global Land Data Assimilation System) hydrological models, and CMIP5 (the World Climate Research Programme’s Coupled Model Intercomparison Project Phase 5) climate data. The research was conducted for the period between September 2006 and October 2015. The TWS data were taken directly from GRACE measurements and also computed from four GLDAS (VIC, CLM, MOSAIC, and NOAH) and six CMIP5 (FGOALS-g2, GFDL-ESM2G, GISS-E2-H, inmcm4, MIROC5, and MPI-ESM-LR) models. The GWS data were obtained by subtracting the model TWS from the GRACE TWS. The resulting GWS values were compared with in-situ well measurements calibrated using porosity coefficients. For each time series, the trends, spectra, amplitudes, and seasonal components were computed and analyzed. The results suggest that in Poland there has been generally no major TWS or GWS depletion. Our results indicate that when comparing TWS values, better compliance with GRACE data was obtained for GLDAS than for CMIP5 models. However, the GWS analysis showed better consistency of climate models with the well results. The results can contribute toward selection of an appropriate model that, in combination with global GRACE observations, would provide information on groundwater changes in regions with limited or inaccurate ground measurements.

Thermal properties of the crust and the lithosphere\u2013asthenosphere boundary in the area of Poland from the heat flow variability and seismic data

High-resolution 3D seismic P-wave velocity model of Poland (Grad et al., Tectonophysics 666:188–210, 2016) and corrected for paleoclimate heat flow map (Majorowicz and Wybraniec, Int J Earth Sci 100(4):881–887, 2011) gridded to a common mesh are used together with four independent thermal models of the crust and upper mantle to calculate heat flow variation with depth and geotherms. Heat flow at Moho depth are calculated and mapped and both confirm large variability with an elevated mantle heat flow (circa 30–40 mW/m2) in the Paleozoic Platform which is some 10–20 mW/m2 higher than Moho heat flow in the north-eastern and south-eastern Poland which belong to a variety of tectonic terranes (the oldest Precambrian Craton, younger Cadomian, Trans-European Suture Zone, Carpathians). Temperatures calculated for the crust show consistent pattern: higher temperatures beneath the Paleozoic Platform and lower temperatures beneath the Precambrian and Cadomian units. At 10 km depth this difference is about 150 °C, about 300 °C at 20 km depth, and about 400 °C at 50–60 km. Assuming the calculated isotherm 580 °C as Curie temperature the magnetic crust thickness was determined as 5–10 km only beneath the Polish Basin, circa 20 km in Carpathians, circa 30 km in Sudetes, and 35–40 km beneath the Precambrian and Cadomian units. Such a thick magnetic crust results from a great depth of Curie temperature, thick crystalline crust, and thin sediments. Mantle heat flow variability is mainly correlating with measured surface heat flow and influences geotherms. Calculated thermal LAB depth follows patterns of heat flow and Moho heat flow variability through Poland with thinnest lithosphere in the high surface heat flow and high mantle heat flow areas. Comparison of this thermal LAB depth estimates with seismic data based LAB depth shows general coincidences when Precambrian Craton vs Paleozoic Platform are considered along the P4 seismic experiment data model (circa 190 km depth vs some 90 km depth, respectively). However, significant differences exist in many areas and especially for the SE Poland when compared with map for the whole of Poland compiled from other seismic reported data.

3-D studies of MT data in the Central Polish Basin: Influence of inversion parameters, model space and transfer function selection

3-D inversion of geophysical data has become a practical, commonly used tool in the interpretation of magnetotelluric (MT) data. However, 3-D inversion is a non-linear and non-unique task and requires adopting additional assumptions. In this paper, we analyze the influence of selection of inversion parameters in the case of previously published, real model for Pomerania region (Poland). This zone is a regional scale 2-D structure, which locally becomes 3-D. The analyzed model was accomplished by inversion of full impedance and tippers from 31 MT stations with the period range from 10 s to 10,000 s. The inversion parameters were chosen to provide the best possible agreement of the model with well-known geophysical and geophysical data.The purpose of the presented work is to determine how the change of some inversion parameters influences previously obtained model, and therefore we check which structure features remain in spite of the change of the implied parameters. A number of tests were performed employing an implementation of the freely available ModEM inversion package. These included the choice of an appropriate initial model and a model covariances evaluation as a means to control smoothness between adjoining model areas. Additionally, we compared the models calculated from all transfer functions (impedances and tippers) and from subsets (only tippers and off-diagonal components of the impedance tensor and tippers). Moreover, the tests with the model coordinate system rotation were performed.Our analysis has shown that the values of covariance matrix coefficients have an evident effect on the results. However, the multiple use of the covariance matrix with small coefficients gives a similar result as its single use with higher coefficients. The initial model and the selection of the transfer function for inversion can significantly change the model. However, changing the orientation of the coordinate system from geographic to the one that is aligned with a regional strike direction does not cause noticeable changes in the solution obtained. It can be only noted that for the rotated coordinate system the obtained model becomes closer to the model of a 2-D regional structure.

Foraminiferal biostratigraphy of the Middle and Upper Jurassic of the Polish Lowlands: the state of the art

The foraminifera-based biostratigraphy of the Middle and Upper Jurassic of the Polish Lowlands was re-evaluated. Biostratigraphic charts providing ranges of the most important foraminiferal taxa characteristic of individual Jurassic stages are presented in relation to the currently used ammonite-based standard stratigraphic divisions. The study contains the new research on the foraminifera fauna and includes earlier results available in published and archival reports. In the Oxfordian and Lower Kimmeridgian deposits, various foraminiferal assemblages were distinguished with reference to the lithofacies in the individual parts of the Polish Basin and varying influences of the palaeogeographical provinces. Additionally, the foraminiferal zones in the Oxfordian and Lower Kimmeridgian deposits of southeastern Poland are distinguished based on detail study of foraminifers.

The only way is up – on Mesozoic uplifts and basin inversion events in SE Poland

Abstract The inversion of a sedimentary basin could be associated with compressional reactivation of basin-forming normal faults, upwards movement of the basement blocks and partial or complete erosion of its sedimentary infill. Basin inversion might be also related to whole-basin uplift that is not linked to the reactivation of basement faults, and results in the development of regional stratigraphic gaps and unconformities. Both types of basin inversion have been documented in SE Poland using seismic data. Regional NW–SE seismic profiles illustrate earliest Late Jurassic (earliest Oxfordian) and earliest Late Cretaceous (Cenomanian) regional unconformities related to regional basin-scale uplifts in the SE segment of the Polish Basin. Late Cretaceous (Turonian?–Maastrichtian) progressive uplift of the Mid-Polish Swell has been documented along the NE border zone of this regional anticlinal structure. The Upper Cretaceous inversion-related sedimentary succession is characterized by an overall progradational character directed from the SW towards the NE. Buried contourite drifts that were detected within the Upper Cretaceous succession using seismic data indicate the existence of contour currents encircling inversion-related intrabasinal morphological barriers. A new tectonic scenario of the Mesozoic evolution of SE Poland would have a significant impact on the modelling of tectonic subsidence and the history of petroleum systems.

A discussion about Valanginian Neocomitinae from Central Poland, their ontogeny and possible origin

In the Valanginian Wąwał section, Central Poland, ammonites are numerous and very well preserved, often with early whorls. This material provides new information and unique details for the study of the ontogeny and relationships within the Neocomitinae. The early ontogenetic stages of the genera Neohoploceras Spath, Karakaschiceras Thieuloy and Neocomites Uhlig from the Wąwał section have been studied in detail and, based on the similarity of the early stages, the close relationship between Neohoploceras Spath and Karakaschiceras Thieuloy is suggested. More distant from them is the genus Neocomites Uhlig, whose early ontogenetic stages are different. The earliest appearance of the genera Karakaschiceras Thieuloy and Neohoploceras Spath in the Wąwał section may suggest that the Polish Basin, with its intermediate character between the Tethyan and Boreal realms, could have been the best place for their early development and the beginning of their later evolutionary path.

Pyritization of dinoflagellate cysts: A case study from the Polish Middle Jurassic (Bathonian)

Bathonian mudstones and claystones were deposited in a shallow epicontinental sea of the Polish Basin (the Ore-Bearing Częstochowa Clay Formation). They are represented by two units, differing in stratigraphical and facies development. Dinoflagellate cyst taxa are dominated by Ctenidodinium. The effects of the environment and sedimentation rate on pyritization intensity were compared using two locations. Where the sedimentation rate was probably faster and grey mudstones were deposited under dysoxic conditions, the extent of cyst pyritization was relatively minor. In contrast, where the deposition of black claystones was slower with deposition under more suboxic conditions, very intense pyritization led to complete infilling of cysts by pyrite. Pyritization required transport of iron, probably from microbial iron reduction, and sulphide, from bacterial sulphate reduction, from the surrounding sediment into the open dinoflagellate cysts. The supply of sulphur was the limiting factor. Controls on pyrite crystal habit by the organic composition of the dinoflagellate cysts walls and cells are inferred by the observation that dinoflagellate cysts uniquely contain mainly cuboid pyrite crystals.

The Distribution of Petroleum Resources and Characteristics of Main Petroliferous Basins along the Silk Road Economic Belt and the 21st‐Century Maritime Silk Road

AbstractThe Silk Road Economic Belt and the 21st‐Century Maritime Silk Road Initiative, abbreviated as the Belt and Road Initiative, is a primary development strategy of China's future international cooperation. Especially, the energy resource cooperation, including oil and gas resources cooperation, is an important part of this initiative. The Belt and Road has undergone complicated geological evolution, and contains abundant mineral resources such as oil, gas, coal, uranium, iron, copper, gold and manganese ore resources. Among these, Africa holds 7.8% of the world's total proven oil reserves. The oil and gas resources in Africa are relatively concentrated, with an overall low exploration degree and small consumption demand. Nigeria and Libya contain the most abundant oil resources in Africa, accounting for 2.2% and 2.9% of the world's total reserves, respectively. Nigeria and Algeria hold the richest natural gas resources in Africa, occupying 2.8% and 2.4% of the world's total reserves, respectively. Africa's oil and gas resources are mainly concentrated in Egypt, Sultan and Western Sahara regions in the northern Africa, and the Gulf of Guinea, Niger River and Congo River area in the western Africa. The Russia–Central Asia area holds rich petroleum resources in Russia, Kazakhstan, Turkmenistan and Uzbekistan. The potential oil and gas areas include the West Siberia Basin, East Siberia Basin and sea continental shelf in Russia, the northern and central Caspian Basin in Kazakhstan, the right bank of the Amu‐Darya Basin, the East Karakum uplift and the South Caspian Basin in Turkmenistan, and the Amu–Daria Basin, Fergana Basin, Afghan–Tajik Basin and North Ustyurt Basin in Uzbekistan. The Middle East oil and gas resources are mainly distributed in the Zagros foreland basin and Arabian continental margin basin, and the main oil‐producing countries include Saudi Arabia, Iran and Iraq. The Asia Pacific region is a new oil and gas consumption center, with rapid growth of oil and gas demand. In 2012, this region consumed about 33.6% of the world's total oil consumption and 18.9% of the world's total natural gas consumption, which has been ranked the world's largest oil and gas consumption center. The oil and gas resources are concentrated in China, Indosinian, Malaysia, Australia and India. The abundant European proven crude oil reserves are in Norway, Britain and Denmark and also rich natural gas resources in Norway, Holland and Britain. Norway and Britain contain about 77.5% of European proven oil reserves, which accounts for only 0.9% of the world's proven reserves. The Europe includes main petroliferous basins of the Voring Basin, Anglo–Dutch Basin, Northwest German Basin, Northeast German–Polish Basin and Carpathian Basin. According to the analysis of source rocks, reservoir rocks, cap rocks and traps for the main petroliferous basins, the potential oil and gas prospecting targets in the Belt and Road are mainly the Zagros Basin and Arabic Platform in the Middle East, the East Barents Sea Basin and the East Siberia Basin in Russia–Central Asia, the Niger Delta Basin, East African rift system and the Australia Northwest Shelf. With the development of oil and gas theory and exploration technology, unconventional petroleum resources will play an increasingly important role in oil and gas industry.

AN OLD INDUSTRIAL PLANT AS A MUSEUM – FROM CONCEPT TO IMPLEMENTATION. SELECTED ISSUES CONCERNING THE PROTECTION OF POLAND’S INDUSTRIAL HERITAGE

The article discusses the problem of protecting industrial plants by preserving them in the form of museums established directly in historical production facilities dating from the era of industrialisation. The author presents the trends and plans of selected museums as well as the ways in which they were built; she also deals with the problem of defining the institution of an industrial open-air museum and its specificity. The creation, aims, organisational structure and financing of the Museum of the Old Polish Basin in Sielpia Wielka, the Historical Metallurgical Plant in Maleniec, the Museum of Oil and Gas Industry in Bóbrka and the "Guido" Mine in Zabrze are discussed in their historical contexts as well as on the basis of archival materials and source publications. The common features and tendencies from the Communist period are concluded by describing the communities involved in the protection of industrial cultural values, the idea behind the way the institution is organised, and the sources of financing.

Mercury enrichment indicates volcanic triggering of Valanginian environmental change

The Valanginian stage (Early Cretaceous) includes an episode of significant environmental changes, which are well defined by a positive δ13C excursion. This globally recorded excursion indicates important perturbations in the carbon cycle, which has tentatively been associated with a pulse in volcanic activity and the formation of the Paraná-Etendeka large igneous province (LIP). Uncertainties in existing age models preclude, however, its positive identification as a trigger of Valanginian environmental changes. Here we report that in Valanginian sediments recovered from a drill core in Wąwał (Polish Basin, Poland), and from outcrops in the Breggia Gorge (Lombardian Basin, southern Switzerland), and Orpierre and Angles (Vocontian Basin, SE France), intervals at or near the onset of the positive δ13C excursion are significantly enriched in mercury (Hg). The persistence of the Hg anomaly in Hg/TOC, Hg/phyllosilicate, and Hg/Fe ratios shows that organic-matter scavenging and/or adsorbtion onto clay minerals or hydrous iron oxides only played a limited role. Volcanic outgassing was most probably the primary source of the Hg enrichments, which demonstrate that an important magmatic pulse triggered the Valanginian environmental perturbations.

Rare earth element distribution in fine-grained deposits from the uppermost Triassic and Lower Jurassic of the Polish Basin: provenance and weathering in the source area

Nineteen samples of uppermost Triassic and Lower Jurassic claystones and mudstones, which were formed in the epicontinental Polish Basin, were analysed by inductively coupled plasma mass spectrometry (ICP-MS) for rare earth elements (REE) and other selected trace elements (Sc, Y, Th, Zr and U). The results indicate that the source of most of the claystones and mudstones studied were sedimentary rocks of the upper continental crust of old cratonic areas, where the protolith had a mainly felsic character. However, in the latest Triassic a characteristic layer formed, implying significant input from mafic volcanic protolith. It was also found that moderately intense chemical weathering usually favoured increased concentration of the rare earths. Extremely strong hydrolysis, related to episodes of very hot and humid climate (greenhouse events), caused conspicuous impoverishment in REE in residual clays. Weathering and recycling processes modified the composition of REE to some extent, but generally did not obliterate the original characteristics of the protolith. In some samples, enrichment in rare earth elements was observed, caused by admixtures of accessory minerals (being a main carrier of REE) and/or increased sorting during recycling.

Late Carboniferous–early Permian events in the Trans-European Suture Zone: Tectonic and acid magmatic evidence from Poland

The Trans-European Suture Zone (TESZ) links the East and West European Platforms. It is concealed under Meso-Cenozoic cover. Available seismic data show that the lower crustal layer in the TESZ is an attenuated, ~200km wide, SW margin of Baltica. The attenuation occurred when Rodinia broke-up, which gave rise to evolution of the thinned, thus relatively unstable margin of Baltica. It accommodated accretions during Phanerozoic events. We focus on acid magmatism, specifically granitoid, observed close to the SW border of the TESZ in Poland. This border is defined by the Dolsk Fault Zone (DFZ) and the Kraków-Lubliniec Fault Zone (KLFZ) on which dextral wrenching developed as a result of the Variscan collision between Laurussia and Gondwana. The granitoids at the DFZ and KLFZ were dated at ~300Ma. In the Variscan foreland that overlaps the TESZ, orogenic thickening continued to ~307–306Ma, possibly contributed to melting of the thickened upper continental crust (εNd300=−6.0 to −4.5) and triggered the tectonically controlled magmatism. The wrenching on the TESZ border faults caused tensional openings in the basement, which promoted magmatic centers with extrusions of rhyolites and extensive ignimbrites. The Chrzypsko–Paproć and Małopolska magmatic centers were developed at the DFZ and KLFZ, respectively. The magmatic edifices commenced at ~302Ma with relatively poorly evolved granites, which carried both suprasubduction and anorogenic signatures, then followed by more evolved volcanic rocks (up to 293Ma). Their geochemistry and inherited zircons suggest that the felsic magmas were mainly derived from upper crustal rocks, with some mantle additions, which included Sveconorwegian and older Baltican components. The complex TESZ, with Baltica basement in the lower crust, was susceptible to transient effects of mantle upwelling that occurred by the end of the Variscan orogeny and resulted in an episode of the “flare-up” magmatism in the North German–Polish Basin.

Late Jurassic facies architecture of the Złoczew Graben: implications for evolution of the tectonic-controlled northern peri-Tethyan shelf (Upper Oxfordian–Lower Kimmeridgian, Poland)

In recent years, numerous wells have been completed in the area of the Zloczew Graben. Drill cores and data collected from wells have led to the recognition of an Upper Oxfordian–Lowermost Kimmeridgian sequence and to the construction of a 3D model of the graben with distribution of facies. Six facies types were distinguished, composed of numerous microfacies representing outer-, middle-, and inner-ramp depositional systems. The boundary of the Planula/Platynota zones is indicated by the transition from mid-inner carbonate ramp facies to mixed, carbonate–siliciclastic outer-ramp facies, as well as by appearance of debrites and calciturbidites. The distribution of gravity-flow deposits reflects the pattern of fault zones of the Zloczew Graben and their Late Jurassic activity. Comparison of Oxfordian–Lowermost Kimmeridgian facies types from central and southern Poland enabled the reconstruction of the general facies architecture in the Polish part of the northern peri-Tethyan shelf belonging to the Malopolska Block. The distribution of Upper Oxfordian–Lowermost Kimmeridgian facies follows the block structure of the basement and was controlled by reactivation of Paleozoic tectonic blocks in the Late Jurassic. The results of studies in the Polish basin correspond well to Upper Oxfordian–Lower Kimmeridgian sequences known from the ramp systems of western Europe where the basic change in deposition, from a carbonate ramp towards mixed, carbonate–siliciclastic sedimentation, was related to both North Atlantic and western European tectonics.