Polish Geological Institute

This study aims to establish the chronology of lower sediment deposition in Lake Żarnowieckie, a glacial-origin lake located in the coastal zone of the Baltic Sea in northern Poland, through radiocarbon dating. An 8-meter-long sediment core was extracted from the lake’s bottom. Then, 21 samples of the bulk sediment, as well as plant remains, were selected from the layers of visible lithological borders. The samples underwent ABA chemical preparation and were subsequently processed into graphite for analysis using the MICADAS accelerator mass spectrometer at the 14C and Mass Spectrometry Laboratory in Gliwice. A total of 20 dating results, ranging from 2,300 BP to near the limit of the radiocarbon method were obtained. Comparison of these results with expert palynological and lithological analyses indicated that 12 dates were overestimated due to the reservoir effect and redeposition of older material. The reservoir effect in Lake Żarnowieckie is estimated at several hundred to 2,000 years, consistent with findings from other Polish lakes. Two samples showed particularly large age discrepancies compared with the age-depth model, suggesting the possible redeposition of older material and sedimentation disturbances, such as sublacustrine landslides or increased erosion. Additionally, two samples (with ages approaching the radiocarbon method limit) originated from deep, sandy layers that were likely deposited by glacial processes before the formation of the lake. The remaining six dates were considered reliable and were subsequently used to construct the age–depth model. The sedimentation rates derived from the model vary distinctly between lithological units.Research supported by EU funds FSD – 10.25, Development of Higher Education Focused on the Needs of the Green Economy, European Funds for Silesia 2021–2027: The modern methods of the monitoring of the level and isotopic composition of atmospheric CO2 (project no. FESL.10.25-IZ.01-06C9/23-00). This research was partially funded by the Polish Geological Institute, National Research Institute (Grant No. 62.9012.2309.00.0), and partly by the NCN Project, Opus 23 (UMO-2022/45/B/ST10/03167) and Opus 29 (2025/57/B/ST10/03700).

Very small-strain stiffness parameters derived from seismic methods are commonly used in landslide investigations to describe subsurface mechanical conditions. In practice, these parameters are often interpreted in terms of slope stability. However, their role in identifying the internal structure of landslide bodies is still not fully recognized, especially in geologically complex flysch terrains.This study examines the significance of very small-strain shear modulus (G₀) for interpreting the internal structure of deep-seated landslides developed in the Carpathian Flysch. The analysis is based on two slow-moving landslides instrumented with deep inclinometer boreholes and monitored over periods of 9–10 years. Long-term inclinometer records provide information on cumulative deep-seated displacements and their vertical distribution within the landslide bodies.Seismic surveys were carried out along profiles located within the landslides, and very small-strain stiffness distributions were derived from shear-wave velocity measurements supported by laboratory-based bulk density data. Instead of focusing on the integration methodology, the study compares stiffness profiles directly with long-term displacement patterns and geological information at borehole locations.The results indicate that variations in very small-strain stiffness reflect differences in lithology, degree of weathering, and structural discontinuities within the landslide bodies. Zones characterized by relatively high stiffness values may correspond to less weathered but strongly fractured flysch units, while lower stiffness values are typically associated with colluvial material or highly disturbed rock masses. Importantly, similar stiffness values can be linked to different kinematic behaviors, highlighting that stiffness parameters alone do not describe landslide activity.The comparison of geophysical stiffness data with long-term monitoring records demonstrates that very small-strain stiffness is particularly useful for identifying internal structural domains rather than for direct assessment of landslide stability. The study emphasizes the role of long-term inclinometer monitoring as a reference framework that constrains the interpretation of geophysical results. The findings support a more informed use of seismic stiffness parameters in landslide studies and contribute to improved characterization of landslide structure in flysch terrains.

The carbon isotope signature of carbonates across the Lower-Middle Triassic transition was investigated to reconstruct environmental change and carbon cycle dynamics in the Holy Cross Mountains (HCM, Poland). This area was located in the southeastern part of the semi-enclosed Germanic Basin, intermittently connected to the western Tethys Ocean through tectonically controlled marine gateways.The dataset is derived from the uppermost Olenekian to upper Anisian interval of the Piekoszów IG-1 borehole. This approximately 240 m thick succession comprises mudstones, marly limestones, dolostones and limestones, locally nodular, classified as wackestones to packstones and subordinate grainstones. These deposits document the carbonate ramp setting ranging from restricted marginal to open-marine conditions. A distinctive red mudstone horizon in the lower Anisian records short-lived emersion within the ramp. The biostratigraphic framework of this succession is constrained by conodonts, bivalves, echinoderms, brachiopods and miospores.The δ¹³C curve across the Olenekian-Anisian transition ranges from -3.16‰ to +0.70‰ VPDB. A positive shift recorded close to the Olenekian-Anisian boundary broadly corresponds to the Spathian-Anisian carbon isotope event and represents a potential regional chemostratigraphic marker. A pronounced negative excursion (down to -3.82‰) is observed within a lower Anisian dolostone interval. Miospores identified above this interval indicate the Perotrilites minor palynozone of the Lower Muschelkalk, allowing precise stratigraphic calibration of the isotope record. A second significant positive shift (+3.06‰) occurs near the Bithynian-Pelsonian boundary and correlates with coeval carbon isotope excursions documented elsewhere in the Germanic Basin and the western Tethys. This is followed by a gradual decline culminating in a negative excursion in the upper Anisian.The δ¹³C fluctuations observed in the late Olenekian and early Anisian are interpreted to reflect local palaeoenvironmental conditions within a shallow, partly restricted epicontinental sea. Restricted circulation and episodic freshwater input likely modified the dissolved inorganic carbon pool through mixing with isotopically light terrestrial carbon and reduced exchange with open-marine reservoirs. In contrast, more positive δ¹³C values during the middle and late Anisian coincide with the development of open-marine carbonate ramp conditions, enhanced carbonate production and improved basin connectivity.The δ¹⁸O values display a wide scatter consistent with variable early diagenetic conditions and facies-controlled overprint in a restricted to shallow-marine setting. The absence of systematic δ¹³C-δ¹⁸O covariance suggests that the main carbon isotope trends are not dominated by late-stage diagenetic alteration.Overall, the isotope record from the HCM reflects regional palaeoenvironmental dynamics in the Polish segment of the Germanic Basin related to tectonically driven changes in basin connectivity, water circulation and third-order transgressive-regressive cycles, supporting the use of δ¹³C trends as tools for regional chemostratigraphic correlation across the Lower-Middle Triassic transition.

Two generations of palaeolakes (Lipowo I, Lipowo II), associated with the termination of the Last Glacial, were documented in the Suwałki Lake District, northeastern Poland. Multiproxy analyses and radiocarbon (14C) and OSL dating were performed on lacustrine sediments. The older generation of basins developed among gradually melting dead-ice blocks and was eventually buried under mineral deposits at the end of the Allerød. The younger generation formed after the complete melting of dead-ice blocks and reflects environmental changes from the late Allerød to the Holocene. Observed changes in sedimentation style during the Late Glacial and early Holocene were linked to significant climatic shifts and their consequences. These changes were also recorded in palynological analyses, fossil Cladocera, geochemical data, and stable isotope results.The vegetation composition during the Younger Dryas shows distinct regional features, including the strong development of Juniperus shrubs and herbaceous and grassy plants at the beginning of this stage, as well as the appearance of Picea abies in its later part. Northeastern Poland was more similar to northeastern Europe than to the rest of the Polish Lowlands, reflecting the paleoclimatic gradient that occurred in Poland during the Younger Dryas. The Holocene section of the Lipowo II profile also documents the first cold Holocene event at 11.4 ka.Cladocera analysis for the studied lakes revealed remains of only 10 species in Lake “Lipowo I,” belonging to three families: Chydoridae, Bosminidae, and Daphniidae, with most remains attributed to Chydoridae. These species were mainly cold-water tolerant, and their frequency was low (max. 2200 ind./cm³). In Lipowo II, 25 Cladocera species were identified, representing various ecological zones, including open-water taxa requiring higher water temperatures. The number of individuals increased to a maximum of 6000 ind./cm³, indicating more favorable conditions for Cladocera development. Environmental changes recorded in vegetation and zooplankton are further supported by stable isotope analyses. Total organic carbon (TOC) and total nitrogen (TN) increased from approximately 2% to 53% and from 0% to 3.8%, respectively. Multiproxy analyses enabled the reconstruction of significant environmental changes associated with the transition from glacial to interglacial conditions in northeastern Poland.

Understanding the processes that govern fracture development in upper crustal rocks is crucial for characterizing the mechanical response of the Earth’s crust. While conventional failure criteria capture many aspects of fracturing observed in laboratory experiments, they fall short in explaining how system-spanning fractures emerge from the interaction and coalescence of microcracks distributed throughout a deforming rock mass. Additionally, empirical rupture models rarely distinguish the relative roles of tensile and shear mechanisms in macroscopic failure. In this study, we explore the influence of the geometrical arrangement of pre-existing microcracks on fracture formation by analyzing the elastic stress perturbations they generate, employing two-dimensional Finite Element Method (FEM) simulations. This approach allows us to quantify how cracks with different orientations modify the surrounding stress field, producing localized zones of elevated tensile and/or shear stress that may act as favorable pathways for fracture propagation. By systematically varying microcrack orientation and distribution, we can map how stress concentration patterns interact, providing a framework for understanding fracture coalescence in heterogeneous rock materials. Our results reveal that the orientation and spatial arrangement of pre-existing microcracks dictate the directions and magnitudes of stress perturbations, creating preferential trajectories for system-spanning fractures. In particular, regions of high tensile and shear stress develop between interacting cracks, offering a physical explanation for the formation of interconnected fracture networks, including en echelon fracture systems, under varying geometrical configurations. These findings indicate that macroscopic shear fractures may originate not only from the coalescence of tensile cracks formed during early deformation stages but also from the interaction of pre-existing cracks with different orientations, especially where tensile stress is concentrated at crack tips. The study demonstrates that the geometry of pre-existing microcracks is a primary factor controlling the spatial organization of resulting fracture networks. Fractures accommodating shear deformation, typically oriented at approximately ±30° to the axis of maximum compression, can arise from the coalescence of mode I cracks due to localized tensile stress concentration, rather than requiring shear-dominated initial conditions. This insight bridges a gap between classical fracture mechanics and observations of natural and experimental rock fracture systems, highlighting the interplay between tensile and shear mechanisms in shaping macroscopic failure patterns. Overall, our work emphasizes the importance of microstructural geometry in governing fracture evolution, offering a quantitative, framework which integrates LEFM analytical results with FEM-based models to predict the emergence of complex fracture networks from initial microcrack distributions. By linking local stress perturbations to large-scale fracture patterns, this study provides a more comprehensive understanding of the conditions leading to system-spanning fractures in the upper crust.

This study evaluates the potential of fine-grained waste gneiss as a soil improver, with particular emphasis on its chemical and grain composition and its effects on plant growth. The experimental material consisted of mixtures of fine-grained waste gneiss with varying proportions (from 0.38% to 7.5% in the pot) supplemented with varying proportions of dolomite (from 0.14% to 0.22% in the pot). Pot experiments were conducted for 57 days under controlled conditions using selected crops. Plant response was assessed based on growth rate, green mass production, and dry mass. For most tested variants, the results demonstrated a dose-dependent enhancement in plant productivity associated with gneiss supplementation. Compared to the control, experiments containing higher proportions of fine-grained gneiss resulted in an increase in green and dry mass from 8.14% to 78.73% and by 12.5% to 96.88%, respectively. Additionally, strong positive correlations between gneiss content and yield parameters (Pearson’s r > 0.8) were observed. In contrast, the dolomite fraction mainly conceptually affected soil chemical properties, including calcium and magnesium availability and pH stabilization. Overall, the findings suggest that fine-grained waste gneiss acts as a growth-promoting soil conditioner, as evidenced by the marked improvement in plant biomass. The findings confirm the high potential of waste gneiss as a functional soil improver, supporting sustainable resource management and aligning with the principles of the circular economy.

The aim of the study is to assess the effect of diagenesis on the reservoir properties of Carboniferous sandstones in Western Pomerania (NW Poland). The research focuses on Mississippian (Łobżonka Shale, Gozd Arkose, and Drzewiany Sandstone formations) and Pennsylvanian (Wolin, Rega, and Dziwna formations) rocks. A comparative analysis of the sandstones in the individual formations was carried out. The sandstone samples taken from 13 deep boreholes were studied petrographically (using a polarizing microscope, cathodoluminescence, and a scanning electron microscope), and petrophysical features were measured. The Carboniferous sandstones are represented mainly by quartz arenites ranging from very fine- to medium-grained and arkosic and lithic arenites from fine- to coarse-grained. The main diagenetic processes that affected the porosity and permeability of quartz arenites were compaction and cementation. Compaction reduced the primary porosity by an average of about 60% and cementation by about 40% in the Pennsylvanian sandstones. Primary porosity of arkosic and lithic arenites was affected mainly by compaction, cementation, and dissolution. Arkosic arenites have lost an average of 80% of their primary porosity as a result of mechanical compaction. The porosity of these sandstones increased due to the dissolution of mainly feldspar grains and the formation of secondary porosity. Among the Mississippian sandstones, quartz arenites of the Łobżonka Shale Formation exhibit unfavorable reservoir properties (porosity approx. 1%, impermeable). The volcaniclastic arkosic and lithic arenites of the Gozd Arkose Formation have poor reservoir qualities (porosity usually around 5%, mostly impermeable). The quartz arenites of the Drzewiany Sandstone Formation show the best reservoir properties (porosity of about 18%, permeability up to 1000 mD). The Pennsylvanian sandstones, quartz arenites of the Wolin and Rega formations, are characterized by good reservoir qualities (porosity approx. 10%, permeability up to 200 mD), while the Dziwna Formation sandstones show worse properties (porosity approx. 10%, often impermeable).

Protecting groundwater against pollution from agricultural sources is a key aspect of sustainable management of soil and water resources. Implementation of sustainable strategies for agricultural production can be supported by modeling tools, which allow us to quantify the effects of different agricultural practices in the context of groundwater vulnerability to contamination. In this study we present a method to assess groundwater vulnerability to nitrate pollution based on a combination of the SWAT agro-hydrological model and the DRASTIC index method. SWAT modeling was applied to assess different scenarios of agricultural practices and identify solutions for sustainable management of soil and groundwater and reduction of nitrate pollution. The developed method was implemented for groundwater resources in a study area (Puck Bay region, southern Baltic coast), which represented a complex multi-aquifer system formed in Quaternary fluvioglacial deposits (sand and gravel) separated by moraine tills. In order to investigate the effects of different agricultural practices, 12 scenarios have been defined, which were grouped into four classes: crop type, fertilizer management, tillage, and grazing. An overlay index structure was applied, and ratings and weights to several factors were assigned. All analyses were processed using GIS tools, and the results are presented in the form of maps, which categorize groundwater vulnerability to nitrate pollution into five classes, ranging from very low to very high. The results reveal significant variability in groundwater vulnerability to nitrate pollution in the study area. Agricultural practices have a very strong influence on groundwater vulnerability by controlling both recharge rates and nitrogen losses from the soil profile. The most pronounced increases in vulnerability were associated with scenarios involving excessive fertilization and intensive grazing. Among crop types, potato cultivation appears to pose the greatest risk to groundwater quality.