The Vrgoračko polje is a karst field with a surface area of 37 km 2 and an altitude of between 20 and 28 m above sea level, situated at the southern edge of the Dalmatian Zagora. During the Quaternary the polje was flooded for variable periods of time and a lacustrine environment was established. A multidisciplinary study of drill-cores, outcrops and geoelectric measurements recognised five main sedimentary facies: laminated sediment, redeposited sediment, coarsegrained carbonate debris, littoral clay and lacustrine chalk. Based on the facies analysis, depositional environments developed during the Holocene include aquatic lacustrine littoral and deeper-water environments. The terrestrial environment is represented by a desiccated lake phase. The littoral clay facies (filling depressions and caverns in the karst relief) is laterally equivalent to the deep-water laminated facies (varves?). A stratigraphic break between littoral clay and lacustrine chalk could be time-equivalent to disturbed laminated sediments deposited in deeper-water and to local intercalations of coarse-grained carbonate debris in shallow-water facies sediments. These features could have been the result of a neotectonic event (earthquake), which triggered debris flows of colluvial material from slopes around the lake, and this could also have changed the hydrological regime of the Vrgoračko polje and affected subsequent depositional facies. According to 14 C dating, deposition of the lacustrine chalk started at the beginning of the Mid-Holocene Warm Period (7686±36 aBP) with a sedimentation rate of approximately 0.51 mm a-1 during the Middle, and 0.58 mm a-1 during the Late Holocene to today. Calculated carbonate production was estimated at 1050 gm-2 a-1. A temporary phase of subaerial exposure of the lake is indicated by desiccation cracks and two bioturbated palaeosol horizons. The described depositional environments and sediment facies found in the Vrgoračko polje could be considered to represent a typical Quaternary lacustrine sedimentation pattern for other Dinaric karst poljes. described in the Cerkničko polje, Slovenian Dinaric karst (VAL-VASOR, 1689; PLENIČAR, 1954; SMREKAR, 2000). Similarly, in the karstic Lake Banyoles (NE Spain), MORELLÓN et al. (2014) reported intense groundwater inflow that leads to the fluidization and re-suspension of previously deposited sediments. Seasonal autumn flooding of the Vrgoračko polje may (re)establish a lacustrine environment that lasts through the winter as confirmed by zonal vegetation around the polje (Fig. 1). Likewise, seasonal runoff through estavelles and ponors into the Neretva River (E of the Vrgoračko polje), and the artificial Prigon tunnel draining into the Baćinska Lakes (S of the Vrgoračko polje), leave the Vrgoračko polje dry throughout the summer. The Matica River is the only permanent stream that meanders from its springs in the NW, splits to the south and the east and then sinks (Fig. 1). The altitude difference between the springs, estavelles and ponors is approximately 8 metres. T...
<p>The &#272;ur&#273;evac Sands constitute a wide area of extraordinary small-scale dune relief in the Podravina (northeastern Croatia), along the central part of the southern Drava river valley. They are thought to have been formed by reworking of fluvial material due to strong northern winds. Their significance is evident from the geometry of the dunes (shape, orientation, thickness), and the presence of intra- and post-formational alteration (pedogenesis). In addition, the elevated heavy mineral content puts the sands in the position of potential ore deposit.</p> <p>The objective of this study is to explore this aeolian archive in an attempt to extract relevant palaeo-environmental information and to compare it with similar landscapes across Europe. The lithology (grain-size) and intra-formational alteration (palaeosoils) as well as geochemical signatures are investigated from outcrops in an abandoned sand pit to define phases of sand movement and landscape stability. Radiocarbon dating of charcoal, optically stimulated luminescence (OSL) dating of quartz, and historical archives are used to develop a geochronological framework. The heavy and light mineral fractions of the sands are used to determine their composition, provenance and detailed sedimentological context at the time of deposition. A digital elevation model of the region is used to gain insight into the geometry of the dunes, while geo-electric soundings and mechanical coring are applied to investigate the vertical and lateral variations in sand lithology and thickness, as well as intraformational soils.</p> <p>At first sight, the dune landscape seems to have a chaotic nature, showing an irregular alignment of smaller parabolic, linear and domal shaped dunes. Although, larger structures may also be classified as complex long-walled transgressive dunes or compound en-echelon parabolic dunes. The thickness of the dune sand can clearly be traced on geo-electrical profiles, where the dry dune sand appears to generate a different signal than the underlying water-saturated fluvial material. Furthermore, the results show that phases of sand movement occurred before and after the B&#248;lling-Aller&#248;d (B-A) interstadial, as well as during the early Holocene and up to the 19<sup>th</sup> century. Phases of stability are witnessed by the presence of slightly altered parent material (presence of organic carbon, slightly finer grain size, and decalcified) and are dated to the B-A interstadial, and several episodes in the Holocene. The heavy mineral content is dominated by garnet, while muscovite is strikingly more present in the Holocene sediments. This may be due to either a change in source material (new Holocene Drava river sediment) and/or changing aeolian dynamics. Overall, these new findings obtained from the &#272;ur&#273;evac Sands area correlate rather well with other regions in the Pannonian Basin as well as the North European Plain, especially in terms of the timing of events.</p> <div id="ConnectiveDocSignExtentionInstalled" data-extension-version="1.0.4"></div>
<p>The Republic of Serbia wishes to evaluate the various options for disposal of radioactive waste and used sources. The evaluation is supposed to be based on international solutions for radioactive waste, the current and future waste inventory of Serbia, and the various possible solutions for final disposal. A high-level assessment of the geological situation in Serbia, as well as an initial screening for suitable host rock material, is inherently included in such an evaluation, and is the aim of the current work.</p><p>Based on available information such as orohydrographical and morphostructural maps, the 1:300.000 geological map, individual but undisclosed 1:100.000 geological mapsheets, the 1:500.000 neo-Alpine tectonic map of Serbia, seismic hazard maps for different return periods, and various scientific publications dealing with the geological and tectonic evolution of Serbia and surroundings, several initial recommendations can be formulated that will support and assist the decision-making process in finding a suitable site (and host rock).</p><p>Roughly, the territory can be divided into two different regions with contrasting tectonic behaviour. South of the Danube, the relief intensity is significant and mountain massives with altitudes up to 2000 m and more are present. The most important morphostructural units include the Dinarides, the Vardar Zone, the Serbo-Macedonian Massif and the Carpatho-Balkanides. This region is characterised by outcropping and subcropping material that underwent significant deformation during various tectonic pulses in the past, resulting in a vast area with rather impermeable meta-sedimentary and metamorphic rocks. Neo-Alpine tectonics from the Oligo-Miocene onwards resulted in significant vertical uplift of the southern massifs, this pattern being interrupted by isolated and closed subsiding depressions. Throughout the region south of the Danube, magmatic rocks of various age, type and composition can be found, which are elsewhere being considered in international solutions for geological disposal. The same is valid for the previously mentioned meta-sedimentary and metamorphic rocks, which include flysch sequences, and several schist and gneiss occurrences.</p><p>North of the Danube, the Pannonian Basin is characterised by significant subsidence, up to several thousand meters since the Oligo-Miocene. The basin is filled with continental clastic deposits, with several prominent clay occurrences of sufficient thickness and depth. Clay rock and (plastic) unlithified clay are often being considered in international solutions for geological waste disposal.</p><p>The neo-Alpine tectonic map indicates the presence of numerous faults: gravitational, reverse and strike-slip. Quite a number of these have shown significant activity in the Pliocene and Quaternary, most notably those that mark the boundary between outcropping massifs and subsiding areas (e.g., between the Carpatho-Balkanides and the marginal part of the Pannonian Basin). Near those faults, historical seismic activity has been recorded with magnitudes up to M = 6.5. Seismic hazard seems to be highest in the central and southern part of the country.</p><p>In summary, this short geological reconnaisance of Serbia suggests that basic geological knowledge is available that will help evaluating the various disposal options, both in terms of host rock material (thickness and depth) and a stable geological environment.</p>
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