Geological Quarterly

Trace elements and garnet formation in a distal skarn zone: a case study of the Rudnik deposit, Central Serbia

2024-06-19T20:19:43+02:00

The Rudnik Pb-Zn deposit is hosted in skarns and hornfels formed in the late Oligocene by contact metamorphism of limestones, sandstones and shales. Garnets, together with epidote, represent the main non-metallic minerals in the Rudnik skarn. In the distal skarn zone, the garnets are rare and their occurrence is related to the flow path of hydrothermal fluids. To constrain the hydrothermal and physicochemical conditions, in situ elemental SEM-WDS and LA-ICP-MS analyses, and fluid inclusion microthermometric measurements, were made. The Rudnik garnets from the distal skarn zone are predominantly of andradite-grossular composition (Adr_39.3–88.9Grs_2.9–53.9Alm_0.5–10.0), with a small amount of spessartine. Generally, the Fe-rich garnets show a positive Eu anomaly with LREE enrichment and a HREE flat pattern, with homogenization temperatures and salinities of fluid inclusions ranging from 373 to 392°C and from 14.25 to 15.27% NaCl equivalent, respectively. The trace elements and microthermometric properties indicate that the garnets formed at moderately high temperatures, mildly acidic pH levels and increased oxygen fugacity

Ostracod biostratigraphy and Strontium isotope stratigraphy of the Miocene sequences of the Ayrancı Basin (Karaman/Turkey)

2024-05-29T12:30:32+02:00

We investigate the stratigraphy of the Miocene fossil ostracod fauna from the Ayrancı Basin in southern Turkey, based on five key stratigraphic sections. Abundant ostracods belonging to the Neomonoceratina helvetica-Aurila soummamensis Biozone were found within the limestones of the Mazı Formation. This formation also records the initial appearance of Carinocythereis and Praeorbulina glomerosa curva-Orbulina suturalis, which are indicative of the Orbulina universa planktonic foraminiferal Biozone. The Divlek Formation, characterized by fossiliferous argillaceous limestones and marls, contains a diverse and well-preserved ostracod assemblage, allowing correlation of this lithological unit with the late appearance of Cyprideis during the Miocene. The formation age has been determined to span from the Tortonian, with an age range of 7.1–8.4 Ma based on ⁸⁷Sr/⁸⁶Sr ratios of two samples.

A new approach to analysing the origin and occurrence of amber-bearing deposits of the Upper Eocene, northern Lublin area, SE Poland

2024-07-07T21:56:51+02:00

Eocene sedimentation in the Lublin region reached its peak in the Middle Eocene, followed by a regression in the Late Eocene, which was accompanied by accumulation of significant amber deposits in the North Lublin area. These deposits, located along the south-eastern coast of the Eocene, reflect the abundant resin production in diverse forests during the climatic optimum of the Eocene. Recent research has challenged the earlier notion that amber deposits formed in river deltas and linked them to regressive marine facies. Amber is typically found in low-energy, regressive rock layers such as silt and sand, and its distribution could be significantly affected by environmental changes influencing its secondary occurrence. A recent study focusing on the North Lublin region modelled the structural surface of the Upper Cretaceous to identify areas of amber-bearing deposits. Using data from the PITAKA, Bank HYDRO and Central Geological Archive databases, a comprehensive surface of the Upper Cretaceous at the sub-basin scale was created using ArcGIS software. This approach enabled a better understanding of the paleo-depositional subsurface of the Paleogene deposits. The analysis identified 84 different amber-bearing fields covering a total area of 891.5 km², which corresponds to almost 14% of the study area in the northern Lublin region. These results emphasise the influence of the palaeomorphology of the Late Eocene basin on sediment dynamics in amber-bearing areas. This paper describes a new depositional model for the Eocene amber-bearing formations in the Lublin region and indicates potential amber deposits in this region.

Collective analysis of radiocarbon and luminescence dating results from fluvial deposits in central and southern Poland in the context of INTIMATE stratigraphy

2024-03-04T09:56:13+01:00

We describe a collective analysis of radiocarbon and luminescence dating results from fluvial palaeoenvironments in various Polish regions (lowlands, highlands, mountains, and their forelands) south of the Last Glacial Maximum line. The study used 484 radiocarbon and 130 luminescence dates, for which summed probability density distributions were constructed using the OxCal program. The analysis is juxtaposed against high-resolution INTIMATE stratigraphy. It demonstrates that discontinuous records of fluvial environmental responses in such analyses reveal significantly more detail than studies conducted at individual sites. A strong correlation was observed between peaks in the probability density functions (PDFs) of radiocarbon dates and interstadial periods. Conversely, accumulations of luminescence dates are correlated with stadial periods.

The application of the k-means clustering method in the prediction of the primary and secondary mineral composition of sandstones: a case study from Lower and Middle Jurassic rocks in the Polish Basin

2024-03-26T13:08:36+01:00

Comprehensive knowledge of both the primary and secondary mineral composition of rocks, as well as the diagenetic processes occurring within them, stands as a fundamental requirement for accurately estimating reservoir rock parameters across various geological sectors, such as petroleum geology, geothermal energy, and carbon capture and storage. In the era of widespread automatization, machine learning methods are increasingly being used for interpretation, which, with the support of appropriate datasets and the experience of interpreters, make it possible to draw a variety of conclusions about geological processes occurring within selected geological formations, as well as entire sedimentary basins. We describe the application of the k-means clustering method for the rapid prediction of primary and diagenetic mineral composition using the the example of Lower and Middle Jurassic sandstones in the Polish Basin - one of the main aquifers and a potential reservoir formation. The model was based on the correlation between neutron porosity (NPHI), bulk density (RHOB), interval transit time (DT), deep resistivity (LLD), total natural gamma-ray (GR) and spectral gamma-ray values (K, Th, U), correlated with the results of petrographic, petrophysical and qualitative geochemical analysis. This correlation was the basis for distinguishing 5 different sandy petrofacies with variable primary and diagenetic characteristics typical of Jurassic sandstones in the Polish Basin.

Glaciomorphological features of the North and Middle Lithuania Lowlands

2024-05-07T15:49:45+02:00

Glaciomorphological features of the North and Middle Lithuania Lowlands are described and interpreted. The ridged relief of the morainic plain in the NW part (Akmenė district, North Lithuania) is characterized by mega-scale glacial lineation (MSGL) forms, testifying to the active movement of the glacier; they do not correlate with the sub-Quaternary palaeosurface. The relief structure of the Nevėžis Moraine Plain located farther south includes areas of obscure MSGL that were affected by glaciolacustrine accumulation and abrasion, glaciofluvial accumulation and erosion, as well as intensive land drainage (amelioration) in the 20^th century. Typical MSGL forms in the Mūša-Nemunėlis Moraine Plain and relicts of MSGL forms in the Nevėžis Moraine Plain, as well as patterns of orientation and inclination of macroclast long axes due to mixing of the moraine material (till), reflect the dynamics of the sliding glacier. These features show that the moraine plains of Middle and North Lithuania were formed by an actively moving glacier, which left an identifiable till layer when geological and hydrological conditions allowed.

New miospore data from the Namurian Biały Kamień Formation in the northern part of the Intra-Sudetic Basin (SW Poland)

2024-08-04T13:55:11+02:00

Palynostratigraphic studies of the Carboniferous strata of the Biały Kamień Formation, outcropping in the northern part of the Intra-Sudetic Basin, are reported. This formation had been earlier assigned to the Upper Namurian and Lower Westphalian A on the basis of macrofloral and palynological data (Gothan and Gropp, 1933; Górecka, 1969) but these results needed checking against the modern international miospore zonation. We described many taxonomically diverse miospore assemblages from these rocks, which allowed to include them into two miospore zones, of Crassispora kosankei–Grumosisporites varioreticulatus (KV) and Raistrickia fulva–Reticulatisporites reticulatus (FR). These zones are correlated with part of the interval from the upper part of the Namurian A up to the Namurian C. The miospore zone Cirratriradites saturni–Triquitrites sinani (SS), identified by Górecka-Nowak (1987, 1995) from the Grzędy IG 1 borehole, extends the age range of the Biały Kamień Formation from Upper Namurian A to Lower Westphalian A. The documentation of these zones together with previous results of palynostratigraphic studies of the underlying Wałbrzych Formation corroborates the record of miospore zones of the Serpukhovian and Bashkirian in the Intra-Sudetic Carboniferous and suggests that there is no stratigraphic gap between the Wałbrzych and the Biały Kamień formations.

Hydrogeological and physico-mechanical responses of physically heterogeneous waste rock to storage time and vertical pressure

2024-07-31T20:56:29+02:00

The variability of the selected properties of mining waste under the influence of its long-term storage and increasing vertical pressure is assessed, through tests conducted on five samples of waste rock used in the reclamation of an open-pit mine. It was found that the considerable variability in the mining waste grain size, exhibiting extreme strength and slakeability parameter values, influences the filtration properties of the rock material. Increasing vertical pressure exerted under laboratory conditions resulted in significant grain degradation, material consolidation and permeability reduction. Exponential functions are the most accurate way of characterising the correlations between the rock sample volume density and the filtration coefficient. The test results demonstrated that the oldest waste was characterised by the lowest permeability and highest compressibility. The material with half a year storage time exhibited the highest filtration properties. Waste stored for 15 years and subjected to coal recovery was also characterised by high permeability. The mining waste filtration coefficients obtained for each vertical pressure value were referenced to values characteristic for soil and rock at a water temperature of 10°C (the average annual temperature of shallow groundwater in the area of waste sampling for laboratory testing).

Chemical weathering indices in contrasting fluvial systems: a comparative study from the Lublin Upland and the Sudetes Mountains in Poland

2024-07-22T06:09:28+02:00

The chemical weathering indices in different fluvial systems in Poland are determined, to indicate which factors affect small-scale chemical weathering processes to the greatest degree. The Weathering Index of Parker (WIP), Vogt’s Residual Index (V), the Chemical Index of Alteration (CIA), Harnois’s Chemical Index of Weathering (CIW), and the Plagioclase Index of Alteration (PIA), as well as Rb/Sr and Sr/Cu ratios, were calculated for 30 sediment samples taken from four selected rivers in the Lublin Upland and the Sudetes Mountains, respectively. The median values for the Lublin Upland rivers were as follows: WIP (12.14–13.05), V (0.66–0.83), CIA (31.79–33.93), CIW (36.67–38.07); PIA (25.20–29.84), Rb/Sr (0.32–0.41), Sr/Cu (14.01–19.66). The median values obtained in the Sudetes Mountains were: WIP (49.88–56.25), V (2.03–2.70), CIA (54.73–56.63), CIW (68.60–70.59), PIA (58.48–59.59), Rb/Sr (1.13–2.70), Sr/Cu (5.94–8.14). River sediment samples were also analysed using a scanning electron microscope and XRD diffraction of whole rock samples to identify minerals hosting the elements investigated. The results indicate a higher intensity of weathering processes in the Sudetes Mountains than in the Lublin Upland and corroborated that, besides the climate regime, other factors, such as bedrock lithology, physical erosion and landform type have significant meaning in assessing weathering processes.

Development of a non-perennial to ephemeral fluvial system in continental fault-bounded basin – an ex ample from the early Permian Krajanów Formation of the Intra-Sudetic Basin (NE Bohemian Massif) – discussion

2024-06-19T12:19:28+02:00

Development of a non-perennial to ephemeral fluvial system in a continental fault-bounded basin – an example from the early Permian Krajanów Formation of the Intra-Sudetic Basin (NE Bohemian Massif) – reply

2024-08-02T19:18:36+02:00