Vodonosniki visokega in alpskega krasa so pomembni viri pitne vode. Dinamika toka skozi te vodonosnike je izjemno kompleksna, saj je njihova struktura posledica veefaznega, deloma glaciokraskega ...razvoja v tektonsko aktivnem obmoeju. Debelina vadozne cone visokogorskih kraskih vodonosnikov lahko presega dva kilometra. V clanku predstavljamo in obravnavamo rezultate sledilnega poskusa v alpskem krasu Julijskih Alp (Slovenija), natancneje v Sistemu Migovec, najdaljsem jamskem sistemu v Sloveniji (dolzina = 43 km, globina = 972 m). Jama se razteza pod gorskim grebenom, ki locuje dolini Soce in Save ter tako tvori topografsko locnico med jadranskim in ernomorskim bazenom. V zacetku septembra 2019 smo injicirali tri kilograme uranina v jezero Colarado, priblizno 900 metrov pod planoto in 100 metrov nad nizkovodnim nivojem podzemne vode. Znane izvire v dolinah na obeh straneh razvodnice smo spremljali z rocnim ali samodejnim vzorcenjem in terenskim fluorometrom. Do izjemnega padavinskega dogodka v zacetka novembra sledila nismo zaznali na nobenem od opazovanih mest. Ob dogodku se je sledilo zanesljivo pojavilo le na vzorcevalnem mestu v zgornjem toku Tolminke, kjer je po grobi oceni v 60 urah preslo 60-65 % mase sledila. Na drugih mestih je bil dvig koncentracije, zaradi odsotnosti sledila ali prevelikega razredcenja, premajhen, da bi lahko potrdili pojav sledila. Rezultati kazejo, da vadozni tokovi ob manjsih dogodkih niso sprozili zaznavnega prenosa sledila, pac pa je do tega prislo sele, ko je epifreaticni tok ob izjemnem dogodku dosegel nivo vodnih teles s sledilom. Ce upostevamo celoten cas od injiciranja do zaznave sledila, je navidezna hitrost potovanja 1,7 m/h, ob predpostavki, da je sledilo mobiliziral novembrski padavinski dogodek, pa je navidezna hitrost 70 m/h. Studija opozarja na izzive in pasti pri sledenju vode v alpskih kraskih sistemih ter predlaga nacine, kako se jim izogniti.
Garnet is one of the most abundant heavy minerals present in the Cretaceous – Eocene flysch deposits of the Southeastern Alps and Outer Dinarides (Julian, Brkini and Istrian basins). About 300 ...detrital garnets from the Cretaceous-Eocene flysch deposits of the Southeastern Alps have been analysed by means of electron microprobe and LA-ICP-MS. In the Julian and Istrian basins, supplies are from amphibolite-facies rocks and mafic and ultramafic metamorphic rocks, while in the Brkini basin the latter are almost missing. Moreover, in the Julian and Istrian basins, supplies from skarns, very low-grade metabasites, or from ultra-high temperature metamorphosed calc-silicate granulites are present. Among these different groups, LA-ICP-MS analyses showed that trace element content can be very different in almandine-rich garnets from the different sources. In particular, the source that supplied the Julian Basin is significantly different from that of the Istrian Basin. From the Cretaceous to the Palaeocene the main supplies of Bi-type garnets derived from an area where feldspar-free garnet-bearing rocks were exposed. Successively, Bi-type garnets were supplied from an area where feldspar-garnet-bearing rocks were exposed. The presence of garnets from feldspar-free garnet-bearing rocks in the Brkini and Istrian basins can be ascribed to both recycling of material from the Julian Basin as well as direct input from the same areas that supplied the Julian Basin.
•About 300 detrital garnets have been analysed by electron microprobe and LA-ICP-MS.•Major elements allowed to define some major provenance.•Trace elements are much more sensitive than major elements and better define source rocks.
The Toarcian oceanic anoxic event (ca 183 Ma) coincides with a global perturbation marked by enhanced organic carbon burial and a general decrease in calcium carbonate production, probably triggered ...by changes in the composition of marine plankton and elevated carbon dioxide levels in the atmosphere. This study is based on high-resolution sampling of two stratigraphic successions, located in Valdorbia (Umbria-Marche Apennines) and Monte Mangart (Julian Alps), Italy, which represent expressions of the Toarcian oceanic anoxic event in deep-water pelagic sediments. These successions are characterized by the occurrence of black shales showing relatively low total organic carbon concentrations (compared with coeval strata in Northern Europe), generally < 2%, and low hydrogen indices. On this basis, they are similar to other Toarcian black shales described from the Tethyan region. The positive and negative carbon-isotope records from the two localities permit a high-resolution correlation such that ammonite biostratigraphy information from Valdorbia can be transferred to those parts of the Monte Mangart section that lack these fossils. Spectral analyses of δ¹³Corg values and of CaCO₃ percentages from the sedimentary records of both the Valdorbia and Monte Mangart sections reveal a strong cyclic pattern, best interpreted as an eccentricity signal which hence implies a duration of ca 500 kyr for the negative carbon-isotope excursion. Based on the carbon-isotope curves obtained, the high-resolution correlation between the Italian successions and a section in Yorkshire (Northern Europe) confirms the supposition that the apparent mismatch between the dating of the Toarcian oceanic anoxic event in the Boreal and Tethyan realms is an artefact of biostratigraphy.
The Alps represent an area where many deep groundwater circulations occur as thermal springs. In the Bled case study, the thermal water temperature, at it is discharged to the surface, is between ...19–23 °C. In order to determine the extent (e.g., geometry) and the origin of the pronounced deep circulation system in the Bled area, chemical and isotopic measurements of waters from different hydrogeological systems were performed (e.g., surface water, thermal water, fresh groundwater). Hydrogeochemical methods were used to tie together the above-mentioned parameters. The results have shown that thermal outflow in Bled is determined by the presence of a deep-water circulation system, where the dissolution of carbonates minerals is the main hydrogeochemical process affecting chemical components of natural water flow. The correlation of the major ions suggests that the recharge area is represented by both limestone and dolomite rocks. Moreover, the results of δ18O and δ2H of all samples indicate that the recharge is mainly meteoric precipitation. The recharge altitude was estimated for two sampled fresh groundwater springs. The isotopic compositions of those two springs suggest the range from δ18O = −8.68‰, δ2H = −57.4‰ at an elevation of 629 m to δ18O = −9.30‰, δ2H = −60.1‰ at an elevation of 1216 m. The isotopic analysis has confirmed that the thermal water recharges from altitudes of 1282–1620 m a.s.l.
We present a paleoenvironmental reconstruction for the mountain fringe between the South-Eastern Alps and the Northern Dinarides (NE-Italy/W-Slovenia) during the Last Glacial Maximum. We focused on a ...new sedimentary and paleoecological archive spanning the LGM acme, located in an aggrading, permanently flooded and ponded plain, dammed by an active fluvioglacial megafan. The ecosystem reconstruction, based on two high resolution pollen records, is supported by a rich plant macrofossil flora and constrained by a robust radiocarbon chronology between 26 and 22calka BP. We show evidence for persistence of boreal trees and of different open boreal forest types throughout the LGM at the south-eastern mountain fringe of the Alps and the Northern Dinarides. Fire frequency is responsible for high, oscillating forest openness. The paleobotanical record is discussed in the light of the ecogeographic diversity of the region. A belt formed by Swiss stone pine, larch and dwarf mountain pine on limestone bedrock, and accompanied by Spruce in the floodplain, extended uphill, while proximal outwash plain supported Scots pine and dwarf mountain pine. These differences arise from groundwater regimes rather than from local climate variability. A steep moisture gradient from the semiarid pedoclimatic regime prevailing in the Adriatic alluvial plain to the forested mountain fringe is related to the orographic rainout triggered by southern air circulation. Mesophytic broad-leaved forest trees did not withstand the LGM temperature extremes in zonal ecosystems at the Alpine–Dinaric fringe; however, the fossil evidence suggests a number of microrefugia in karstic and thermal spring habitats of the northern Adriatic.
•Paleoenvironmental reconstruction at Alps–Dinarides fringe during the Last Glacial Maximum•Relationships between regional geological frame, sedimentary environments, and forest history•Persistence of trees and of different types of open boreal forest throughout the LGM
A sediment infill of a small, late Anisian-earliest Ladinian half-graben, sealed by massive limestone of the Schlern Formation is exposed on the northeastern slopes of Mt. Vernar in the eastern ...Julian Alps, Slovenia. The pre-rift base of the succession is formed by a chaotic mixture of massive limestone and limestone breccia of the Anisian platform. Sedimentation in the half-graben started with a 20 m thick thinly bedded pink nodular limestone which is informally named here as the Vernar member. It consists of microbial carbonate and was probably deposited within the photic zone. The Vernar member is overlain by poorly sorted polymict breccias of the Uggowitz Breccia Formation which reaches a thickness of at least 150 m, but pinches out rapidly towards the SE graben margin, reflecting the highly asymmetric basin geometry. Individual beds of breccia represent successive debris flow deposits. The Uggowitz Breccia Formation is followed by a few metres of sandstone and sandy limestone of the Buchenstein Formation. The limestone contains abundant grains of shallow marine origin and terrestrial plant fragments. The overlying post-rift Schlern Formation consists of crudely bedded and massive limestone, covering the graben. The consistent NE-SW strike of the graben-bounding faults and of the smallscale conjugate normal faults observed in the Uggowitz Breccia Formation suggests that the half-graben originated from NW-SE directed extension.
Spring water chemistry and carbon cycling in our study mainly depend on geological composition of the aquifer. The investigated Alpine springs in Slovenia represent waters strongly influenced by ...chemical weathering of Mesozoic limestone and dolomite, only one spring was located in Permo-Carboniferous shales. The carbon isotopic composition of dissolved inorganic carbon (DIC) and suspended organic carbon (POC) as well as major solute concentrations yielded insights into the origin of carbon in Alpine spring waters. The major solute composition was dominated by carbonic acid dissolution of calcite. Waters were generally close to saturation with respect to calcite, and dissolved CO2 was up to fortyfold supersaturated relative to the atmosphere. δ13C of DIC indicates the portion of soil CO2 contributed in water and is related with soil thickness of infiltrating water in aquifer and could be therefore used as a tool for vulnerability assessment. The δ13C of DIC ranged from −15.8‰ to −1.5‰ and indicated less and more vulnerable aquifers. Mass balances of carbon for spring waters draining carbonate rocks suggest that carbonate dissolution contributes from approximately 49% to 86% and degradation of organic matter from 13.7% to 51.4%, depending on spring and its relation with rock type, soil environment, and geomorphic position. Stable oxygen isotope composition of water (δ18OH2O), and tritium values range from −12.2 to −9.3‰ and from 6.4 to 9.8 TU, respectively and indicate recharge from modern precipitation. According to active decay of tritium and tritium in modern precipitation the age of spring waters are estimated to be about 2.6years for springs located in Julian Alps, about 5years for springs located in Karavanke and about 5years for springs located in Kamniško–Savinjske Alps.
► In this study we examine water chemistry and carbon cycling of Alpine springs. ► The major solute composition was dominated by dissolution of calcite. ► More negative δ13CDIC values indicated less vulnerable aquifers. ► Isotopic composition of oxygen indicates recharge from precipitation. ► The age of springs was estimated according to tritium up to 5years.
We present a geomorphological map on a scale of 1:15,000, with detailed sedimentological descriptions, and a general relative spatio-temporal depositional reconstruction of Quaternary sediments in ...the Planica-Tamar Valley (NW Slovenia). After the Last Glacial Maximum, the retreating Quaternary glacier deposited large amounts of glacial sediments. These were followed by Holocene sediments, which differ in their sedimentological characteristics, transport mechanisms, and morphology. These sediments are deposited as sedimentary bodies with complex depositional geometries. They form areas of active, partly active, and inactive sedimentation in response to local/regional climate and bedrock geology. Previous research of the valley was mainly focused on bedrock mapping, while almost completely neglecting Quaternary deposits. This work is the first broader analysis of Quaternary sedimentary deposits in the research area, which offers an insight into the complex geomorphological and sedimentological processes, which shape the current mountainous landscape.
Results are presented of the first airborne LiDAR survey ever flown in Europe for the purpose of mapping the surface expression of earthquake‐prone faults. Detailed topographic images derived from ...LiDAR data of the Idrija and Ravne strike‐slip faults in NW Slovenia reveal geomorphological and structural features that shed light on the overall architecture and kinematic history of both fault systems. The 1998 MW = 5.6, and 2004 MW = 5.2 Ravne Fault earthquakes and the historically devastating 1511 M = 6.8 Idrija earthquake indicate that both systems pose a serious seismic hazard in the region. Because both fault systems occur within forested terrain, a tree removal algorithm was applied to the data; the resulting images reveal surface scarps and tectonic landforms in unprecedented detail. Importantly, two sites were discovered to be potentially suitable for fault trenching and palaeo‐seismological analysis. This study highlights the potential contribution of LiDAR surveying in both low‐relief valley terrain and high‐relief mountainous terrain to a regional seismic hazard assessment programme. Geoscientists working in other tectonically active regions of the world where earthquake‐prone faults are obscured by forest cover would also benefit from LiDAR maps that have been processed to remove the canopy return and reveal the forest floor topography.
PDF
