Geological Survey of Slovenia

A unique record of an Upper Triassic brachiopod (Halorella)-arthropod (Halorina microcoprolites)-microbial (Frutexites) assemblage is documented from iron-rich carbonates filling a neptunian dike and sill system developed in Carnian-lower Rhaetian limestone host rock from Leurdeasa Hill in the Apuseni Mountains, Romania. The host rock at Leurdeasa Hill through which the dike and sill cross-cut is dated as early Carnian by the conodont assemblage. The paleoecology of this brachiopod-arthropod-microbial assemblage along with the paleoenvironmental context and genesis of iron-rich carbonates filling the Upper Triassic neptunian dike and sill system is examined through integrated analyses including paleontology, taphonomy, microfacies, mineralogy and stable isotopes of carbon and oxygen, as well as patterns of rare-earth elements. Frutexites microstructures and their possible microbial origin are documented for the first time in an upper Norian-lower Rhaetian neptunian dike and sill. Given the broad paleogeographic distribution of the brachiopod Halorella during the Late Triassic and the scarcity of marine paleoenvironments from where this genus has been reported, we conclude that the proliferation of significant populations of Halorella alongside with arthropods and microbial consortia were restricted to submarine cryptic paleoenvironments characterized by peculiar conditions, namely, warm waters, temporarily rich in nutrients, in dark habitats. Geochemical data show that the red carbonate infills are predominantly seawater-derived with minor terrigenous input, later modified by Fe-Mn oxide formation, organic matter cycling, and diagenesis, and record short-term apparent cyclic shifts between oxic and suboxic conditions in a semi-restricted neptunian dike/sill system likely linked to episodic biotic blooms and variable water exchange.

This study explores the application of strontium (Sr) isotope ratios (87Sr/86Sr) as geochemical tracers to understand hydrological connectivity and anthropogenic influences in a geologically diverse Alpine river catchment encompassing regions of Austria and Slovenia. Focusing on the Mur River and its tributaries, water samples were collected across 45 sites during three hydrological regimes to capture seasonal and spatial variability. In total, 28 tributaries were sampled to evaluate their influence on the isotope composition of the main river. Isotope analyses using multi-collector inductively coupled plasma mass spectrometry, supplemented by geospatial mapping and multivariate statistics, were combined with measurements of 26 elemental concentrations to investigate land–water interactions and human impacts. The results demonstrate substantial temporal and spatial variability in 87Sr/86Sr ratios (ranging from 0.70853 to 0.71322), reflecting both geological heterogeneity and varying tributary inputs. A preliminary aquatic isoscape was developed, enabling the monitoring of connectivity and the impacts of geological and human influences under varying flow regimes. Tributaries, such as the Mürz River, significantly modulate isotope signatures in the main channel, often overriding local geological signals. The application of isotope pattern deconvolution revealed a contribution of 17

Bauxites are the primary mineral resource for alumina and aluminium production. Recently, there has been growing interest in the chemical characterisation of bauxite, as it is listed as a critical raw material (CRM) by the European Union and can contain elevated content of rare earth elements (REE), which are also listed as CRM. This research focuses on the REE content and distribution across profiles of four Slovenian bauxite occurrences of different ages (Triassic T32+3, Jurassic J31,2, Cretaceous K22,3 and Oligocene Ol2) and their implications for potential genesis. General mineral composition analysed by XRD showed a prevalence of böhmite and kaolinite in all samples except Ol2, where diaspore is the main Al-hydroxide. Minor minerals include hematite, quartz, and anatase. Geochemical ICP-MS analysis showed the lowest REE content in Cretaceous bauxites (average 218 mg/kg) and the highest in Jurassic bauxites (average 711 mg/kg). SEM/EDS inspection revealed different carriers of REE. The main carriers of REEs in all profiles are mostly detrital, with some individual secondary authigenic xenotime, secondary authigenic cerianite (Ce) (T32+3, J31,2), calcioancylite (Nd) or cerianite (Ce) without Th (J31,2, Ol2), lanthanite (Ce) and (Nd). Relatively low P2O5 indicates dispersion of REEs throughout a profile and their adsorption onto Al/Fe oxides and hydroxides and clay minerals. The T32+3, J31,2 and K22,3 bauxites show a changing Eh-pH environment, which supports their categorisation as vadose bauxites, while the Ol2 profile is phreatic bauxite where redox conditions prevailed.

Suspended particulate matter (SPM) and stream sediments (STS) from 66 locations (main channel and tributaries) were geochemically investigated in the Alpine transboundary river Mura to provide an integrated view of the long-term accumulation of pollutants and the present-day pollution status of the catchment, including the distribution of YREE (yttrium and rare earth elements) which are regarded as emerging pollutants due to use of modern technologies. Cluster analysis identified 4 geochemical associations in SPM for the low water regime: (1) Cu, Cd, Bi, Pb, Mn, Ni and Cr; (2) Ca, Sr; (3) U, Fe, Co, Rb, YREE, V, Ti, Mg and (4) Ba, Ga, Al and Li. Six groups were identified for STS samples: (1) YREE, U, Mn, Fe, Ti; (2) As, V, Ga, Al; (3) Ca, Sr, Na; (4) Cu, Ni, Co, Cr, Mg; (5) Ag, Bi, Pb, Cd, Zr and (6) Ba, Zn, Rb and Li. The study concluded that the identified geochemical groups reflect the geological composition of the catchment area as well as anthropogenic impacts, notably mining, steel industry, and urbanisation. The spatial distribution of YREE was identified as an indicator of sediment provenance. Eu and Ce anomalies were observed in SPM, reflecting the local geology, while the Gd anomaly may indicate anthropogenic inputs. The study concludes that STS primarily reflect the geogenic distribution of elements, while SPM is a more sensitive indicators of anthropogenic activities for the Alpine fluvial environment. Study also provides upper background and threshold values for Mura River catchment that may serve as reference values in future environmental studies.

This study aimed to investigate the input of various potentially toxic elements (Ag, Pb, Sb, Bi, Zn, Cd, As, Cu, Hg, Au, Tl, and Mo) into the surface soils of the Mitrovica region, a historically active Pb–Zn mining and metallurgical area in Kosovo. Geochemical analyses and multivariate statistics revealed a strong contamination pattern resulting from anthropogenic inputs of these elements. An ecological risk assessment of soil contamination by these potentially toxic elements was conducted in this region using various indicators. The contamination factors showed extremely high values for Au, Pb, Sb, Cd, As, and Ag compared to European and global background values, indicating very high to extreme soil contamination. The enrichment factors confirmed significant to extremely high enrichment for most elements except Mo and Tl. The geo- аccumulation indexes indices categorized soil as moderately to extremely contaminated, especially for Pb, Ag, As, Bi, Cd, and Zn. The values of both indicators show highly to extremely contaminated soils with most of the analyzed elements, particularly in the cities of Zveçan and Mitrovica. The cumulative ecological risk index was more than thirty times higher than the critical threshold, indicating a serious threat to soil quality and ecological health.