Kralj P.,Geological Survey of Slovenia
Journal of Volcanology and Geothermal Research | Year: 2011
Middle to Upper Pliocene (~3Ma) Grad Volcanic Field (SW Pannonian basin system) encompasses an area of about 3km2, of which some 1.7km2 belong to the outcropping volcanics. Pyroclastic and syn-eruptively reworked volcaniclastic deposits are the most widespread in occurrence. Remains of an autobrecciated lava flow, a residual neck and their peperites are partially reworked by a large debris flow. Volcanic activity occurred in a continental depositional environment dominated by alluvial fan and braided river systems. Streams draining from the north-west to the south-east were infilling a rapidly subsiding Radgona Depression. The style of volcanic activity was mainly explosive and was reinforced by hydrovolcanic processes. Three volcanic centres probably existed, and they migrated spatially and temporally from the north to the south over a distance of some 5.6. km. The rocks of the northernmost volcanic centre are fairly eroded and contain abundant, up to 10. cm sized lherzolite xenoliths. The largest crater developed about 2.5. km to the south. From an early maar stage, a tuff-cone, and subsequently, a tuff-ring evolved. The crater was filled with eroded pyroclastic material and stream load. A new vent became active some 500. m to the south. Initial stage was mainly magmatic and produced pyroclastic flow and fall deposits. Late-stage eruptions were predominantly hydrovolcanic (phreatomagmatic and phreatic), and built up a small tuff-cone having some 300. m in diameter. Trachybasaltic and subordinate basanitic magmas erupting in the Grad Volcanic Field are geochemically distinguishable from the neighbouring occurrences in the South Styrian Basin and the South Burgenland Swell. Relatively lower abundance of TiO2, MgO, Sc, V and Cu, and higher abundance of MnO, P2O5, Zn, Sr, Zr, Hf, Nb, Ba, Ta and U indicate somewhat different source and/or evolutionary pattern. © 2010 Elsevier B.V.
Gale L.,Geological Survey of Slovenia
Geologica Carpathica | Year: 2010
The Slovenian Basin represents a Mesozoic deep-water sedimentary environment, situated on the southern Tethyan passive margin. Little is known about its earliest history, from the initial opening in the Carnian (probably Ladinian) to a marked deepening at the beginning of the Jurassic. The bulk of the sediment deposited during this period is represented by the Norian-Rhaetian "Bača Dolomite", which has, until now, been poorly investigated due to a late-diagenetic dolomitization. The Mount Slatnik section (south-eastern Julian Alps, western Slovenia) is one of a few sections where the dolomitization was incomplete. Detailed analysis of this section allowed us to recognize eight microfacies (MF): MF 1 (calcilutite), MF 2 (pelagic bivalve-radiolarian floatstone/wackestone to rudstone/packstone), MF 3 (dolomitized mudstone) with sub-types MF 3-LamB and MF 3-LamD (laminated mudstone found in a breccia matrix and laminated mudstone found in thin-bedded dolomites, respectively) and MF 3-Mix (mixed mudstone), MF 4 (bioturbated radiolarian-spiculite wackestone), MF 5 (fine peloidal-bioclastic packstone), MF 6 (very fine peloidal packstone), MF 7 (bioclastic wackestone) and MF 8 (crystalline dolomite). The microfacies and facies associations indicate a carbonate slope apron depositional environment with hemipelagic sedimentation punctuated by depositions from turbidites and slumps. In addition to the sedimentary environment, two "retrogradation-progradation" cycles were recognized, each with a shift of the depositional setting from an inner apron to a basin plain environment.
Kralj P.,Geological Survey of Slovenia
Journal of Volcanology and Geothermal Research | Year: 2012
The Upper Oligocene Smrekovec Volcanic Complex (SVC) represents the remains of a submarine stratovolcano which underwent Early Miocene tectonic dissection and large-scale displacement along the Periadriatic Line. According to the lithofacies architecture, abundance and spatial distribution, central, medial and distal zones of the former volcano edifice have been recognized. The zones extend at a distance of 0-2. km, 2-5. km and 5-20. km south of the Periadriatic Line, respectively.Lavas, shallow intrusive bodies, autobreccia, peperite and hyaloclastite deposits occur mainly in the central zone, which is extensively altered under hydrothermal conditions, characterised by the development of zeolites (mainly laumontite), prehnite, chlorite, albite and epidote. Explosive volcanic activity intensified with the evolution of magma from basaltic andesitic to dacitic. Gas- and water-supported eruption-fed density flows are assumed. Their deposits show lithofacies organisation in pyroclastic depositional units (PDUs) similar to either volcaniclastic turbidites (Type 1) or thin subaqueous ignimbrites (Type 2).Volcaniclastic debris flow deposits are developed as volcaniclastic breccia and sandy debris flow deposits; the former occurs in the central and medial zones, and the latter occurs in the medial zone only.The most widespread lithofacies in the SVC are volcaniclastic turbidite deposits. Three types of sedimentary unit (TSU) have been distinguished. Type 1 is 2-5. m thick and dominated by the massive division. It mainly occurs in the central zone. Type 2 is 0.7-3.5. m thick and occurs in the central and medial zones. It comprises the massive division, bedded fining- and thinning-upward division, and a horizontally, wavy and cross-laminated division, topped by massive fine-grained tuff. Type 3 is 0.1-1.5. m thick and mainly occurs in the distal zone. The massive division is absent, and thinly-bedded and laminated divisions are topped by massive fine-grained tuff. Volcaniclastic turbidites were settled from low-density turbidity currents and related suspension clouds.Mixed volcaniclastic-siliciclastic deposits are subordinate in occurrence and restricted to the distal zone. They are commonly reworked by bottom currents. © 2012 Elsevier B.V.
Janza M.,Geological Survey of Slovenia
Natural Hazards | Year: 2013
According to climate change projections, the Alps will be one of the most affected regions in Europe. A basis for adaptation measures to climate changes is the quantification of the impact. This study investigates the impact of projected climate change on the hydrological cycle in the Upper Soča River basin. It is based on the use of climate model data as input for hydrological modelling. The climatic input data used were generated by a global climate model (IPCC A1B emission scenario) and downscaled for local use. Hydrological modelling was performed using the distributed hydrological model MIKE SHE. The simulated impact was quantified by comparing results of the hydrological modelling for the control period (1971-2000) and different scenario periods (2011-2040, 2041-2070, 2071-2100). The climate projections show an increase in the average temperature (+0.9, +2.3, +3.8°C) and negligible changes in average precipitation amounts in the scenario periods. More distinctive are changes in the temporal pattern of mean monthly values (up to +5.2°C and ±45% for precipitation), which result in warmer and wetter winters and hotter and drier summers in the scenario periods. The projected rise in temperature is reflected in the increased actual evapotranspiration, the reduction of snow amount and summer groundwater recharge. Changes of monthly and period average discharges follow the trends of the meteorological variables. Changes in precipitation patterns have a major influence on the projected hydrological cycle and are the most important source of uncertainty. Estimated extreme flows indicated increased hazards related to floods, especially in the near-future scenario period, while in the far future scenario period, distinctive drought conditions are projected. © 2011 Springer Science+Business Media B.V.
Rman N.,Geological Survey of Slovenia
Geothermics | Year: 2014
The already exploited geothermal resources in the Mura-Zala basin are planned to be further developed. In this study I investigated thermal water abstraction and its impact on both the fissured basement aquifers and the intergranular Neogene siliciclastic aquifers. Total abstraction of thermal water in north-east Slovenia summed to 3.1millionm3 in 2011, with very limited artificial recharge supplied through a single reinjection well. This exploitation has resulted in depletion of the aquifers, with decline in aquifer pressure, piezometric groundwater levels and discharge rates, as well as chemistry variation, being evident in many wells. A research monitoring network has been established in 2009 and has been taking hourly measurements in eight wells. These wells are up to 2km deep and tap aquifers in the Upper Miocene sandy Mura Formation. Daily, seasonal and annual trends were interpreted, and the measured overall regionally declining static groundwater levels are alarming, reaching 0.53m per year. Despite the changes in conditions in the aquifers, no change of production temperature has so far been perceived. © 2014 Elsevier Ltd.
Kralj P.,Geological Survey of Slovenia
Journal of Volcanology and Geothermal Research | Year: 2016
Hydrothermal zeolites (laumontite, yugawaralite, analcime, heulandite, clinoptilolite), prehnite and pumpellyite have been recognised in a succession of volcanic, autoclastic, pyroclastic, resedimented volcaniclastic and mixed siliciclastic-volcaniclastic deposits. In cone-building lithofacies association attaining 310 m, the alteration minerals commonly change within a single normally graded depositional unit or alternate in the section on a dm- to m-scale, according to the host-rock lithofacies. Fine-grained deposits rich in juvenile glassy pyroclasts are altered to heulandite and clinoptilolite or analcime, and laumontite widely occurs in coarse-grained host-rocks (lapilli tuff, hyaloclastite breccia, volcaniclastic breccia, hyaloclastites) and fracture systems. In near-vent lithofacies association attaining 420 m, prehnite-laumontite, laumontite-analcime, and laumontite-heulandite-clinoptilolite zones developed as a result of superimposed thermal regime generated by the emplacement of an over 200 m thick sill.The recognised dependence of alteration on porosity, permeability and fracturing of the host-rock is closely related to hydrological conditions in the stratovolcano-hosted hydrothermal system with convective-advective flow regime. After separation of steam and gases from convecting hydrothermal fluids, denser liquids outflowed intermittently, preferentially through steeply inclined (20-30°) high-permeability layers in the stratovolcano edifice. In low-permeability layers the flow was slow and thermal conditions were mainly attained by conduction. Zeolites developed only in coarse- and fine-grained vitroclastic tuffs, presumably by the dissolution of volcanic glass. The interstratified siliciclastic siltstones, tuffites and resedimented deposits with low content of glassy particles are devoid of zeolites and indicate compositional constraint on zeolitisation.Lava flows, cooling in a submarine environment and undergoing disintegration and mingling with the enclosing water-saturated sediment were individual, ephemeral and spatially localised high-temperature hydrothermal systems favourable for the formation of pumpellyite, prehnite and laumontite. © 2016 Elsevier B.V.
Gosar M.,Geological Survey of Slovenia |
Tersic T.,Geological Survey of Slovenia
Environmental Geochemistry and Health | Year: 2012
Five centuries of mining and processing of mercury ore in the Idrija area have resulted in widespread contamination of different environmental compartments. Environmental impacts on a regional and local scale, caused by atmospheric emissions from the Idrija ore roasting plant, were established in the investigations of mercury spatial distribution in soil and attic dust in 160 km 2 area. Very high values were determined in the Idrijca River valley, and they decrease exponentially with the distance from Idrija. Mercury concentrations in attic dust are higher than in surrounding soils and the attic dust/soil ratio changes with distance. Measurements of mercury in the air confirmed widespread dispersion of mercury and showed highly elevated mercury concentrations around roasting plant and mine ventilation shaft. Beside, systematic monitoring of mercury contents in the stream sediments has demonstrated that huge amounts of mercury are stored in areas where ancient overbank sediments were deposited, and there was no decrease in mercury concentration in active sediments during the last 15 years. Recently, interesting and extremely polluted locations of historical small-scale roasting sites in the Idrija surroundings were discovered. Ongoing geochemical study aims to determine the extreme pollution and significance of these sites for wider contamination of soils and aquatic systems. Presented studies have shown that Hg mining in Idrija caused intense pollution of local and regional environment including the aquatic systems in the Gulf of Trieste, which is seen as the final sink of a major part of the Hg stored in soils and river sediments in the Idrija area. © 2011 Springer Science+Business Media B.V.
Zibret G.,Geological Survey of Slovenia
Ambio | Year: 2012
This article presents the impact of the ecological investment in ironworks (dust filter installation) and construction works at a highly contaminated brownfield site on the chemical composition of household dust (HD) and street sediment (SS) in Celje, Slovenia. The evaluation is based on two sampling campaigns: the first was undertaken 1 month before the ecological investment became operational and the second 3 years later. The results show that dust filter installations reduced the content of Co, Cr, Fe, Mn, Mo, W and Zn on average by 58% in HD and by 51% in SS. No reduction was observed at sampling points in the upwind direction from the ironworks. By contrast, the impact of the construction works on the highly contaminated brownfield site was detected by a significant increase (on average by 37%) of elements connected to the brownfield contamination in SS. Such increase was not detected in HD. © Royal Swedish Academy of Sciences 2011.
Gosar M.,Geological Survey of Slovenia |
Miler M.,Geological Survey of Slovenia
Applied Geochemistry | Year: 2011
The MeŽa River Valley has been a center of mining, ore processing and iron- and steel-based metallurgical industry for more than 300 a. This paper deals with stream sediments draining this area. Loads of potentially toxic metals and metal-bearing phases were investigated 10 a after the cessation of Pb and Zn mining. Sediments in the upper MeŽa River Valley show significant pollution with Pb and Zn as a consequence of mining and ore processing. The highest contents of Pb and Zn were found in the MeŽa tributaries, which directly drain mine waste deposits (maximum values: 19,300. mg/kg Pb and 37,900. mg/kg Zn). These results reflect transport of contaminated material from mine waste sites and indicate that the inactive mine and its mine wastes are sources of metal contamination in the surrounding environment. Contents of Cr, Ni, Cu and Co are increased in the lower MeŽa River Valley, in the area of Ravne, as a result of the iron and steel industry. The contribution of the MeŽa River to the metal-load in the Drava River is evident.Metal-bearing phases, identified in stream sediments by SEM/EDS, are assigned to three areas, according to their source and genesis. The MeŽica mining district source area is characterized by ore minerals of geogenic/technogenic origin (cerussite, sphalerite, smithsonite and galena), the Ravne source area is characterized by technogenic trace metal-bearing Fe-alloys, Fe-oxides and spherical trace metal-oxides and the MeŽa and Drava River catchment areas are represented by geogenic metal-bearing accessory and common rock-forming minerals, such as zircon, ilmenite, rutile, sphene, barite and monazite. SEM/EDS analyses of stream sediments agree well with the results of chemical analyses and they prove to be a very useful tool for identification of metal-bearing phases and their characterization according to source and genesis. © 2011 Elsevier Ltd.
Janza M.,Geological Survey of Slovenia
Environmental Earth Sciences | Year: 2010
Karst aquifers are known for their heterogeneity and irregular complex flow patterns which make them more difficult to model and demand specific modeling approaches. This paper presents one such approach which is based on a conceptual model. The model was applied in a karst area of the catchment of Rižana spring (200 km2). It is based on the MIKE SHE code and incorporates the main hydrological processes and geological features of the karst aquifer (diffuse and concentrated infiltration, allogenic recharge, quick and slow groundwater flow, shifting groundwater divides and groundwater outflow from the catchment area). Modeling of evapotranspiration and flow in the upper part of the unsaturated zone is more detailed. For the modeling of groundwater flow in the karst aquifer, a conceptual model was applied which uses drainage function for the simulation of groundwater flow through large conduits (karst channels and large fissures). The model was calibrated and validated against the observed Rižana spring discharge which represents a measured response of the aquifer. The results of validation show that the model is able to adequately simulate temporal evolution of the spring discharge, measured by Nash-Sutcliffe coefficient (0.82) as well as overall water balance. © 2009 Springer-Verlag.