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Povzetek: In this study, we focused on the Pliocene–Early Pleistocene fluvial terraces in the Velenje Basin andreconstructed the morphostratigraphy, sedimentary depositional environment, provenance and age of the graveldeposits using geomorphological, sedimentological, petrographic and chronological analyses. Geomorphologicalmapping revealed the presence of two main river‐terrace groups. The terraces in the older terrace group are severelydegraded and preserved only as remnants capping high ground, while in contrast the younger group is betterpreserved. Detailed lithofacies analyses of four selected stratigraphic sections of the older terrace group show that thegravel was deposited in a meandering and wandering environment. The gravel consists of metamorphic, igneous,volcaniclastic, clastic and carbonate lithologies derived from the north, east and west from the Paka Rivercatchments. To determine the timing of deposition, we performed isochron‐burial dating using cosmogenic 26Al and10 Be. Our new age constraints date the deposition of the older terrace group to 2.7 ± 0.3 Ma. Establishing theaggradation and incision model of the Velenje Basin documents pronounced regional tectonic uplift during thePliocene–Early Pleistocene, which led to incision and the subsequent formation of a terrace staircase.
Ključne besede: isochron‐burial dating, morphostratigraphy, provenance analysis, river terraces, Velenje Basin
Objavljeno v DiRROS: 05.09.2024; Ogledov: 93; Prenosov: 45
Celotno besedilo (7,81 MB)

Povzetek: An important aspect of geochemical studies is determining health hazard of potentially toxic elements (PTEs). Key information on PTEs behaviour in the human body in case of their ingestion is provided with the use of in vitro bioaccessibility tests. We analysed and compared oral bioaccessibility of a wide range of PTEs (As, Cd, Ce, Cr, Cu, Hg, La, Li, Ni, Pb, Sb, Sn, Zn), including some that are not often studied but might pose a human health hazard, in soil, attic dust, street dust, and household dust, using Unified BARGE Method (UBM). Additionally, feasibility of usage of scanning electron microscope techniques in analyses of solid residuals of UBM phases was tested. Results show that bioaccessible fractions (BAFs) of PTEs vary significantly between individual samples of the same medium, between different media and between the gastric and gastro-intestinal phases. In soil, attic dust and street dust, bioaccessibility of individual PTE is mostly higher in gastric than in gastro-intestinal phase. The opposite is true for PTEs in household dust. In all four media, with the exception of Pb in household dust, among the most bioaccessible PTEs in gastric phase are Cd, Cu, Pb, and Zn. During the transition from the stomach to small intestine, the mean BAFs of most elements in soil, attic dust, and street dust decreases. The most bioaccessible PTEs in gastro-intestinal phase are Cu, Cd, Ni, and As. Micromorphological and chemical characterisation at individual particle level before and after bioaccessibility test contribute significantly to the understanding of oral bioaccessibility.
Ključne besede: urban geochemistry, UBM, soil, attic dust, street dust, household dust
Objavljeno v DiRROS: 10.07.2024; Ogledov: 178; Prenosov: 81
Celotno besedilo (2,95 MB)

Povzetek: This study investigates the carbon (δ13Corg) and nitrogen (δ15N) isotopic composition of tertiary lignites and coals from six sedimentary basins: Velenje, Mura-Zala, and Zasavje in Slovenia; Sokolov in Czech Republic, Barito in Indonesia; and Istria in Croatia. The aim is to investigate the correlation between the fine detrital (fD) component and δ13C and δ15N in Velenje lignite samples. Additionally, we aim to evaluate the biogeochemical processes of organic substances during their deposition in all analyzed samples, calculate their δ13CCO2 values and compare the analyzed values of δ13C and δ15N to those reported in the literature. Thirty-two samples were analyzed, predominantly from the Velenje ortho-lignite (Pliocene), with additional lignites and coals from the Pannonian to Paleocene epochs for comparison. Carbon isotopic composition (δ13Corg) ranged from -27.9 to -23.6 ‰, and nitrogen isotopic composition (δ15N) ranged from 1.8 to 7.4 ‰. The fine-detrital lithotypes of the Velenje ortho-lignite exhibited the most negative δ13Corg values due to anaerobic bacterial activity in an intramontane alkaline lake environment influenced by the carbonate hinterland. Moreover, gelification processes affected fine-detrital organic matter more than larger wooden pieces. Terbegovci, Hrastnik meta-lignites, and Barito sub-bituminous coal also displayed low δ13Corg values, indicating limited gelification, while variations in the δ15N values suggested differences in mineralization. The Velenje xylitic lithotypes have higher δ15N values, indicating a more intense mineralization under aerobic conditions. Raša ortho-bituminous coal, deposited in a brackish environment, displayed the highest δ13Corg values and a wide range of δ15N values due to fluctuating water tables in a paralic carbonate platform environment. The lowest δ15N value was observed in the Sokolov Basin lignite coal, indicating minimal mineralization and low bacterial activity. The isotopic composition of CO2 in air (δ13Cair), which was calculated using the δ13C values in lignites and coal, ranged from -8.4 to -3.4 ‰, with Velenje lignite displaying the minimum value and Raša coal showing the maximum value. The determined δ13C and δ15N values of the coal and lignite samples in this research fall within the typical range of world coals.
Ključne besede: lignite, coal, petrography, C and N isotopic composition, gelification, mineralization
Objavljeno v DiRROS: 09.07.2024; Ogledov: 176; Prenosov: 98
Celotno besedilo (20,60 MB)

Povzetek: The ichnogenus Circulichnis Vyalov is a horizontal a ring- or ellipse-shaped burrow and/or locomotion trace of an unknown producer, most likely an annelid or a “worm”, preserved on the bedding plane. This ichnogenus is known over a wide age interval (Ediacaran–Oligocene). Circulichnis demonstrates a wide ecological range and has been found in continental (Mermia ichnofacies), shelf, and relatively deep-water (turbidites) deposits. It is commonly interpreted as a sediment feeding trace, but the peculiarities of its formation remain somewhat mysterious, as it is unclear how the tracemaker reached the sediment surface, as lateral branches of the ring-shaped traces are extremely rare and have only been observed by a few researchers. A rather large specimen of Circulichnis montanus Vyalov, 1971 with a preserved lateral branch was found in the Mospyne Formation (upper Bashkirian, Lower Pennsylvanian) of the Donets Basin. This discovery confirmed the assumption made by Alfred Uchman and Bruno Ratazzi regarding the peculiarities of formation of Circulichnis. According to these authors, a single ring-shaped Circulichnis indicates an attempt to forage at a specific level in the sediment, while the lateral branches of Circulichnis are part of a vertical shaft leading to another level within the sediment. The study of Circulichnis montanus from the Donets Basin has confirmed that at least variant C of the Circulichnis formation scheme proposed by Uchman and Ratazzi is correct, i.e. the lateral branch is a horizontal or subhorizontal part of a generally vertical shaft. However, it is important to note that the correctness of variants A and B of the Uchman and Ratazzi scheme cannot be excluded. To answer this question unequivocally, new finds of well-preserved Circulichnis are necessary.
Ključne besede: trace fossils, Circulichnis, Pennsylvanian, Ukraine
Objavljeno v DiRROS: 09.07.2024; Ogledov: 170; Prenosov: 121
Celotno besedilo (5,35 MB)

Povzetek: The groundwater characteristics of the Učja aquifer were investigated using geochemical and isotopic data. The water discharge and physico-chemical properties of the groundwater and the Učja River reflect the climate that is characteristic of the area. The mixed snow/rainfall regime is characteristic for the Učja Valley, with the highest discharges appearing during the spring snowmelt and autumn precipitation, and the lowest discharges in the winter and especially summer months. The temperature of the groundwater and the Učja River is lower in winter and higher in summer. The specific electrical conductivity values indicate a very permeable carbonate aquifer. Higher conductivity values were observed in spring and autumn at all sampling sites, which is related to snowy and rainy periods. The groundwater from the Učja aquifer indicates a uniform type of water (Ca-Mg-HCO3), w it h Ca2+, Mg2+ and HCO3– the most abundant ions. Differences in Ca2+ and Mg2+ concentrations and in the Mg2+/Ca2+molar ratio between sampling sites were observed. Those springs with lower Mg2+ and lower Mg2+/Ca2+ molar ratios indicate limestone recharge areas, and those springs with higher Mg2+ and molar ratios indicate interaction with the dolomite hinterland. The pH values confirm alkaline waters characteristic of carbonate aquifers. The hydrogen (δ2H) and oxygen (δ18O) isotope values suggest the main source of water is from precipitation from a complex mixing of maritime and continental air masses. An altitude isotopic effect is observed with minor δ18O and δ2H depletion at higher altitude sampling sites compared to those springs at lower altitudes. The altitude isotopic effect is most prominent in spring. The δ13CDIC values indicate the dissolution of carbonates and the degradation of organic matter.
Ključne besede: groundwater, hydrogeochemistry, isotopes, cross-border aquifer, Učja Valley
Objavljeno v DiRROS: 09.07.2024; Ogledov: 205; Prenosov: 134
Celotno besedilo (4,48 MB)