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.
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.
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.
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.
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.