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U skladu s Pravilnikom o praćenju stanja radioaktivnosti u okolišu (NN 40/2018) i podacima iz Akcijskog plana za radon za razdoblje 2019. – 2024. (NN 118/2018), nužno je provesti mjere zaštite radnika na mjestima gdje se pojavljuje radon i obavljati periodička mjerenja, a u svrhu zaštite radnika. Mjerenja koncentracija radona provedena su u neaktivnom rudniku sveta Barbara u Rudama, koji predstavlja podzemni objekt turističke, nastavne i znanstvene namjene. Mjerenja su provedena detektorima Radon Scout Home tvrtke Sarad ponovljenim mjerenjima u nekoliko navrata u periodima po dva mjeseca na dvije mjerne točke (Slika 1) te povremenim višesatnim mjerenjima koncentracije radona u rudniku te mjerenjem koncentracije radona u zraku tla u neposrednoj blizini ulaza u rudnik uređajem RTM 2200 SG za mjerenje radona i potomaka tvrtke Sarad. Mjerenja su pokazala da su koncentracije radona većinom niže od vrijednosti 300 Bq/m3 , referentne vrijednosti za radon u zatvorenim prostorima i na radnim mjestima. U slučaju povišenih koncentracija, uređaj za vjetrenje rudnika i održavanje mikroklimatskih uvjeta u rudniku bi se palio i u kratkom vremenu smanjio vrijednosti koncentracije radona na niže od referentne. Povećane koncentracije radona u rudničkoj atmosferi povezane su s periodima nižeg atmosferskog tlaka i kišnim razdobljima. U skladu s Pravilnikom, radnici koji prime godišnju efektivnu dozu veću od 1 mSv, a manju od 6 mSv smatraju se izloženim radnicima kategorije A. U skladu s ICRP, 2014 (ICRP, 2014. Radiological Protection against Radon Exposure. ICRP Publication 126. Ann. ICRP 43(3), prema provedenim mjerenjima kroz godinu dana i usklađivanjem prosjeka s realnim brojem radnih sati provedenih u objektu, zaključeno je kako je efektivna doza za radnike kroz radnu godinu (416 sati) 0, 67 mSv/god.

Passive rift setting is characteristic for Neogene extensional basins within Mediterranean basin and Alpine belt. Area is mostly well explored for oil and gas with populated and industrialized regions Neogene basins are characterized by syn-rift reservoirs and overlaying post-rift regional seals Challenging prospective site characterization. Basin architecture is mainly predefined by tectonic control while the sedimentary environments include alluvial fan, fan delta and submarine fan bodies. Short and fan like bodies are characterized by course grained sediments which are a dominant target for CO2 storage within the interval. Storage capacity constraints consists of variable lithology (mineral property uncertainties in well log porosity estimation)- mixed carbonate and silicate composition of syn- rift succession and volcanic rocks change of matrix type of course grained sediments (due to depositional conditions and diagenesis).

In the Croatian part of the Pannonian Basin System, near Voćin, a 45.9 m long stratigraphic section was recorded. Concentrations of naturally occurring radioelements (K, U, Th) and dose rate were measured, and 33 samples were taken to measure TOC (Total Organic Carbon). According to Lüning & Kolonic (2003), time-consuming organic geochemical analyses can be replaced by gamma-ray spectrometry in black shale systems, but shallow- marine organic-rich systems, similar to ours, are generally characterized by the absence of a stable U/TOC relationship. An attempt was made to establish a correlation between the measured values of natural radioactivity and the TOC values of the samples using artificial neural networks (ANNs). Our results show that there is a moderate correlation between uranium and dose rate (DR) concentrations with TOC, but there is insufficient data so far to train ANNs properly. The radiometric data were obtained with a gamma-ray spectrometer and the values TC (Total Carbon) and TIC (Total Inorganic Carbon) were determined with Analytik Jena multi EA 4000. TOC was calculated from TC and TIC. Radiometric data supplemented by additional analyses can be used for sequence stratigraphic analysis (Omidpour et al, 2021), which could be the next step in this research, and provide more input variables for ANNs.

Syn-rift rock infill and tectonic control on depositional environment distribution in the eastern part of Drava Depression were reconstructed based on 3D seismic data interpretation, integration of exploration wells’ data and making use of tectonostratigraphic approach to sequence stratigraphy. Rift phase in the study area is characterized by the formation of half-graben, graben, sag, and supradetachment basins as well as by synthetic transfer zone and structural highs. The syn-rift rock infill was subdivided into sequences of different order that correspond to rift stages characterized by different rates of extension or to local rift migration. Unlike the ones formed in the early rift stage, the rift climax structures were predefined by tectonic transport along extensional detachments, which represent the principal syn-rift normal fault system in study area. Complex structural evolution controlled various depositional processes. Early rift stage was characterized by continental deposition in alluvial fan, fan delta and lacustrine environments. Rift climax stage corresponded with marine deposition in shallow water, fan delta, subaquatic fault aprons and deep marine environments, followed by intense volcanic activity. Syn-rift tectonics exerted primary control on the sedimentary infill. Synthetic transfer zone, slopes of subsided hanging wall fault blocks and fault scarp slopes presented main sediment transfer zones for deposition in form of alluvial fans, fan-deltas and subaquatic fault aprons. Main depocenters can be structurally correlated with synforms in extensional detachments. Research structured in this way could be effective for regional assessment of prospective reservoirs in syn-rift rocks within the continental (passive) rift system. Due to the complexity of the sediment infill, as well as the structure of the syn-rift basin, various well data, reliable seismic data and understanding of tectonic control on syn-rift sedimentary characteristic are needed. Interpretation of rift tectonostratigraphic boundaries that can be correlated with the activity of normal faults, mapping of seismic facies and lithofacies as well as analysis of paleostructural relationships enables the mapping of depositional environments and locations of prospective sites for HC accumulation and CO2 storage. Correlation with petrophysical properties together with spatial distribution of CO2 density in reservoir conditions enables to model CO2 storage capacity potential.

Istočni dio Dravske depresije okvirno obuhvaća površinu od 5200 km2 čija debljina neogensko- kvartarne ispune lokalno može doseći i više od 6 km. Unutar neogensko-kvartarnih naslaga potvrđena su ležišta nafte i plina prilikom istraživanja koja su se provodila više od 50 godina. Unatoč ovako dugom razdoblju istraživanja i proizvodnje nafte i plina, regionalna bazenska analiza pokazuje da još uvijek postoji potencijal u pronalaženju novih ležišta nafte i plina. Dodatna mogućnost iskorištavanja dubokog podzemlja nastaje kao posljedica trenda prelaska na obnovljive izvore energije i trenda dekarbonizacije gdje ovaj dio Hrvatske ima potencijal u iskorištavanju geotermalnih, skladištenju ugljičnog dioksida i u podzemnom skladištenju energije. Povišeni geotermalni gradijent lokalno može biti i veći od 5 °C/100 m omogućuje definiranje objekata prikladnih u različitim vrstama iskorištavanja geotermalne energije i to iz iz neogensko- kvartarnih stijena te iz stijena podloge neogena sa značajnom sekundarnom poroznošću. Potencijal za uskladištenje ugljikovog dioksida i za podzemno skladištenje energije povećavat će se s vremenom, budući da je većina naftnih i plinskih polja na ovom području pri kraju proizvodnje.

Conventional methods of solving time to depth relations needed for successful interpretation of seismic data and later construction of geological model include vertical seismic profiling and construction of synthetic seismogram based on available well log data from acoustic and density well logs. However, when re-evaluating the potential of mature basins that had its peak exploration and production in the pre-1990’s, this data is often lacking and/or the spatial distribution data is too irregular. As the main controlling factor of the acoustic properties of the rocks is lithology in relation to compaction, we propose the usage of “sandstone to shale” ratio and general lithology in regard to the stratigraphic interval (Pliocene, Upper Miocene, Lower and Middle Miocene and Base Neogene categories) along with burial depth as a controlling factor for determining time to depth relations in wells lacking data for the abovementioned conventional approach. In this way the time to depth relation is controlled as permeable versus impermeable lithologies based on the interpretation of conventional well logs. Initial research was performed using data from four wells with vertical seismic profiling data using the multi-layer perceptron networks. Successfulness of the learning was tested on one additional well which also had vertical seismic profiling measurements. The successfulness of the prediction, although lower than in learning dataset, proved to be more accurate than using the time to depth relations from the nearest well.

Tectonostratigraphic approaches to sequence stratigraphy provide an exploration tool for predictable characterization of the spatial and temporal distribution of depositional systems in rift basins. Pulsating extension can result in more tectonostratigraphic packages bounded with unconformities [1]. These units can be a result of tectonic activity of a different order, from single fault or subsidence episode, when reduced to the simplest [2], to the regional scale of the entire infill of one tectonic regime [3]. In order to utilize units for practical use in different basins and data resolution conditions, Rift tectonostratigraphic sequences (RS) are suggested. RS are defined as tectonostratigraphic units resulting from the pulsating extension, i.e., tectonic cycles of a different order (magnitude) controlled by the fault movements. This type of units represent genetically related sediments bounded by unconformities and/or their correlative conformities predominantly controlled by tectonic subsidence. Their boundaries determine the rank of each unit in the sense previously defined by Embry [4], whereas the difference is that the boundaries are primarily set by tectonic activity. More precisely, the 1st order (i) boundaries are widespread unconformities coinciding with a significant shift in tectonic setting (e.g., syn-rift to post-rift), while the highest order boundaries i+1th are set by the individual movements along fault or the smallest subsidence episode. Each RS consists of two systems tracts - Fault active system tract contains sediments influenced by intense fault activity, while Fault stagnation system tract encompasses sedimentary succession characteristic of fault quiescence. Thus defined units can illustrate basin evolution and can be used at different temporal and spatial scales, especially if abundant seismic data is available, overcoming the lack of well data for spatial correlation. RS are tested in SW part of the Pannonian Basin System, continental rift type basin characterised by episodic tectonic movements, migration of depocenters, and complex lithology.

Suvremeni razvoj raznih grana proizvodne djelatnosti kao i napredak tehnologije zahtijevaju odgovarajuću opskrbu mineralnim sirovinama. Pojedine sirovine posebno su tražene u proizvodnji i razvoju novih proizvoda, a njihova ograničena opskrba ili čak prekid dobave mogu ozbiljno ugroziti proizvodnju i daljnji razvoj, ugroziti sigurnost radnih mjesta te poljuljati lokalno gospodarstvo. Stoga je zadovoljavajuća i pravovremena opskrba ključnim sirovinama nužan preduvjet svakodnevnog funkcioniranja suvremenih gospodarskih tokova, a time i bitna odrednica strateškog planiranja svake države. Nedovoljna dostatnost pojedine sirovine na tržištu može biti posljedica nedostatne domaće proizvodnje i ovisnosti o uvozu s udaljenih tržišta, ali i prekida opskrbe uslijed ekonomskih, prirodnih i geopolitičkih faktora. Ti čimbenici također utječu na čestu fluktuaciju cijena sirovine, koja se dalje odražava na planiranje proizvodnje, cijenu konačnog proizvoda, kao i na poremećaje u proizvodnji ako volatilnost cijena ugrožava zacrtane proizvodne i razvojne ciljeve, a svakako može utjecati i na smanjenje konkurentnosti pojedinih industrija na tržištu. Sirovine nužne za proizvodnju, a nedostatne na domaćem tržištu, podložne čestim promjenama u dostupnosti i cijeni te povećanog rizika u opskrbi, smatraju se kritičnim sirovinama (European Commission Communication, 2011). Često se kod ove problematike naizmjence koristi izraz „kritične sirovine“ i „kritične mineralne sirovine“, budući da mineralne sirovine svojom brojnošću i obujmom proizvodnje čine najveći dio kritičnih sirovina.

Proper assessment of the distribution of lithological composition in the subsurface is one of the key elements in the deep-geological characterization. Conventional estimation of lithology distribution has high dose of uncertainty in regional surveys, where wells are widely and irregulary spaced. The purpose of this paper was to analyze the data using both geostatistics and geological knowledge as objectively and realistically as possible.

Analysis of lithology and lithology related variables in the subsurface is a key component in exploration of subsurface. The conventional way is to use different mapping algorithms to determine the properties in the inter well area based solely on well data or using seismic explorations (attribute analysis ; Radovich & Oliveros, 1998) in order to reduce uncertainty. Artificial Neural networks are also used for this purpose but more as a deterministic approach than a stochastic one (Brcković et al., 2017). For this purpose, a small volume of subsurface in the SW part of Pannonian Basin, representing an old small oil field which is covered by 3D seismic and several wells was selected. The artificial neural networks were first trained on a seismic attribute set belonging to the well traces and afterword the prediction was performed in the inter-well volume using 100 trained networks. The final result was obtained by P90 values of the categorical values that represent different lithologies. By this way the uncertainty of the lithology prediction in the inter well area has been significantly reduced, especially in this case where to few well point data were available to provide a variogram model for conventional deterministic and stochastic approaches.

Formation of the Lower and Middle Miocene rocks in Eastern part of the Drava Depression, as well as in the entire North Croatian Basin, is associated with rifting processes and sedimentary infill of the depocenters created during the syn-rift tectonic phase. Surface outcrops of Lower Miocene succession consist of alluvial sandstones and conglomerates, while Middle Miocene sediments are composed of Lithothamnion limestone’s to marls, indicating sedimentation in shallow marine environment. Core samples from exploration wells differ in lithology - from rockfall breccia and debris conglomerates to both shallow and deeper marine sediments of various lithology. Syn-rift sedimentation usually comprises Miocene volcanic rocks confirmed both in on outcrops and from the well data. Seismic 3D data and interpreted seismic facies suggest that identified lithologies of Lower and Middle Miocene could be spaciously linked. Rift sequence stratigraphic approach (Prosser, 1993) defines tectono-stratigraphic units, which are associated with cogenetic fault activity during the syn-rift phase. The syn-rift tectonic phase units are primarily detected by tilting of reflexes in the hanging wall units and by other seismic facies characteristic that are specific for the syn-rift sedimentation. This is how the pre-rift, syn-rift and post-rift, main tectono- stratigraphic units were interpreted and mapped in this study. In thicker portions of Lower and Middle Miocene successions, the rift sequence architecture can also be studied by interpretation of smaller units - system tracts. Interpreted seismic data pinpoint to cogenetic formation of depocenters as a result of extensional reactivation of the pre-Neogene WNW- ESE striking faulted structures that happened during Lower and Middle Miocene. Syn-rift depocenters were formed either directly in the hanging wall of these reactivated faults or along newly formed normal faults that were structurally predefined by the older pre-Neogene faulted structures. Pre-rift units are usually overlain with initial rift system tract, i.e., the basal seismic facies defined on seismic sections. The initial rift system tract can be distinguished in the thickest portions of the Lower and Middle Miocene strata as onlaping or downlaping on the pre-rift units. Main syn-rift system tract is characterized by: 1) significant vertical offsets along normal faults, 2) tilting of the hanging wall blocks, and 3) seismic facies of marginal fan-aprons. In marginal areas of the syn-rift depocenters only a portion of the main syn-rift system tract can present entire syn-rift succession. In the same time, the well data indicate that initial and main syn-rift system tracts comprise of the entire Lower Miocene and part of the Middle Miocene sediments. Immediate post-rift system tract is characterized by cessation of normal fault activity, onlap on the syn-rift sediments and marked paleo-structures as well as by continuous seismic facies. Immediate post-rift system tract is composed of the upper portion of the Middle Miocene together with the lowermost Pannonian sediments. In the study area, the late post-rift system tract represents the Lake Pannon infill, excluding its lowermost portion. This study suggests that the rift sequence seismo- stratigraphic analyses provides the basis for delineation of prinicipal tectono-stratigraphic units, which can give an additional information on the evolution of the rift basin in Drava Depression. In regions with significant thickness of these rock units in the deep subsurface, this methodology can be used for mapping of the Lower and Middle Miocene rock units in more detail. In this way achieved results can also facilitate the spatial correlation of the Lower and Middle Miocene rocks regionally.

One of the key elements in regional geological subsurface exploration is a valid estimate of lithology distribution. The conventional way is to use different mapping algorithms to determine the properties in the interwell area based solely on well data or using exploration seismics (attribute analysis ; RADOVICH & OLIVEROS, 1998) to reduce uncertainty. Lithological properties of rocks in the subsurface are commonly estimated based on well data using either conventional deterministic approach or stochastic algorithms with previously expressed variograms, respecting the already established contacts between the lithostratigraphic units. Since the uncertainty, spatial and temporal variability cannot be avoided, the aim of this research is to estimate the lithological composition of the rocks in the area between wells, as realistically as possible. Variogram, as a starting point, is a basic term of geomathematical analysis which represents random field structure and it can only depend on the distance between the measured points and on the difference in values between them (ANDRIČEVIĆ et al., 2006). In addition to the well data interpretation, an important role in determining the lithological composition has also recently been given to the application of seismic attribute analysis (KOSON et al., 2014, PIGOT et al., 2013). Artificial neural networks are also used in evaluating the lithological composition (BRCKOVIĆ et al., 2017). In this relatively new method of data processing an algorithm is expected to learn from a set of available data and adapting to new conditions, functioning in the way the biological neural networks do (RUMELHART et al., 1986). The main characteristics of artificial neural networks are exploiting unclear and incomplete data, good nonlinear evaluation of sample relationships, using a large number of different parameters and acquiring new knowledge through the learning process from previous experiences. By using the mentioned geomathematical tools, analysis was performed on well data (Figure 1) from Pannonian sediments in eastern part of Drava Depression. These data includes categorical (lithology categories) and continuous variables (seismic attributes). Since all of this is aimed at better reconstruction of subsurface geology, the main goal of the research is to develop a methodology that will eventually merge well and seismic data with analyses made by artificial neural networks, in order to obtain a more realistic characterization of the lithological composition of clastic sediments in the area between wells, to enable regionally extensive reconstructions.

Analysis of natural hydrocarbon micro seepage is sometimes used by the petroleum industry to assess the occurrence of mature source rocks in poorly explored basins. Various applications of the method have also sought to pinpoint the location of commercially viable subsurface accumulations of oil and gas. The aim of this study was to compare and contrast soil air results anomalies within two geographically distinct, underexplored areas in the Pannonian Basin of Croatia and Slovakia, and perform a controlled test to determine whether the soil gas readings were repeatable, and whether the gas compositions obtained were consistent with subsurface data. Soil air samples were collected at sampling intervals of approximately 100 and 600 meters from an average boring depth of 1 meter. A subset of the samples were obtained during seismic acquisition operations so that results could be correlated with subsurface structure. Gas components of the samples were measured by gas chromatography to discriminate C1 to C4 in a suspected oil-prone area of Croatia, and from C1 to C5 plus CO2 content in a suspected gas- prone survey area of Slovakia. Gas composition and concentrations of the analyzed Croatian samples indicate a thermogenic origin for all of the soil gases, and infer the presence of mature source rocks in the subsurface. Gas concentration and composition anomalies suggest that their origin derives from subsurface micro seepage of both heavy and light oils. Occurrences of C1-C2-C3- C4 (-C5) distributions are most likely due to organic facies differences, maturity, thermogenic and biogenic mixtures as well as alteration processes such as biodegradation and water washing. In Slovakia, anomalous CO2 concentrations on surface are consistent with the presence of a known subsurface CO2 accumulation, hence this approach may also help delineate the risk of high CO2 concentrations. Multiple control samples were collected at various stations and analyzed in the laboratory by high resolution gas chromatography. Results confirm the reproducibility of the subject soil gas sampling method.

One of the key elements during regional geological subsurface explorations is a valid estimate of lithology distribution. Lithological properties of the rocksin the area between wells is conventionally estimated based on well data using either conventional deterministic approach or by stochastic algorithms. Because the uncertainty, spatial and time variability cannot be avoided in geology, the aim of this research is to determine theoretical lithological composition of rocks in the area between wells, as realistically as possible. Variogram, as a starting point, is a basic term of geomathematical analysis which presents random field structure and it can only depend on the distance between measured points and on the difference in value between them (Andričević et al., 2006). Indicator kriging is used as a main method for estimation the spatial distribution of the lithological composition. It builds the cumulative distribution function at each point, based on the behavior and correlation structure of indicator transformed data points in the neighborhood (Isaaks and Srivastava, 1989). Theoretical model which represents fluvial facies with five different lithologies was made in Petrel E&P software platform. The aim was to achieve "the most accurate" model that best shows real relations of facies to the original theoretical model, by using mentioned geomathematical tools as an introduction to the processes which will be performed on actual well data.

Predmet istraživanja disertacije je vezan za utvrđivanje uticaja društvenih mreža, kako tradicionalnih, tako i virtuelnih, na marketing i prodajnu funkciju organizacija, sa posebim akcentom na organizacije turističke delatnosti. Posebnu pažnju disertacija posvećuju definisanju naučne metodologije istraživanja društvenih mreža u funkciji marketinga usluga. Razvoj i uvođenje koncepta modela upravljanja društvenim mrežama poslovnih sistema, naročito je značajno u organizacijama turističke delatnosti. Na primeru zimskog turizma prikazana je implementacija predloženih metodoloških rešenja. Centralni problem koji se proučava vezan je za inkorporiranje tradicionalnih društvenih mreža u poslovni sistem organizatora putovanja i iskorišćavanje potencijala koje upravljanje ovako tretiranim, grupisanim i povezanim klijentima omogućava. U svrhu toga, svi poslovni procesi touroperatora su razloženi i sistematizovani po fazama, sa objašnjenjem uloge svake od tih faza u procesu upravljanja implementiranim društvenim mrežama postojećih i potencijalnih klijenata. U disertaciji će biti predstavljen Model upravljanja društvenim mrežama poslovnih sistema, pogotovo u uslužnom sektoru turizma. The object of research is identification of influence social networks, traditional as well as virtual, has on organization marketing and sales function with special attention on organization in tourist sector. Special attention of dissertation includes definition of the methodology of scientific research in domain of social networks in services marketing. Development and introduction of business system social network management conceptual model is of great importance for companies in tourism. Implementation of suggested methodological solutions is presented on winter tourism case. The main problem studied is incorporation of traditional social networks in business system of tour operator and exploitation of potential that treated, grouped and connected clients enables. In that case all the business processes of tour operators has been decomposed and systematized in stages with additional explanation of every stage in the process of implemented social networks management of existing and potential client’s. In dissertation there will be presented Model of Social Networks Management in organizations, especially in tourist service sector. Key words: Tourism, Tourism Marketing, Network Theory, Small World Theory, Social Networks, Social Groups, Virtual Social Network, Virtual Social Media, Model of Social Network Management, Principle of Authority Transfer, Authority of Relationship, Business Success Helix, Tour Operator, Snow Sport Industry, Ski Population, Segmentation of Ski Population

Well logs from selected well within the Sava Depression, Pannonian Basin were selected for testing the applicability of standard deviation curve trends as a general outliner for sedimentation trends, well log marker position and enhancing correlation possibility. These logs consisted of classic electric well log measurements which include self potential and shallow and deep resistivity. Standard deviation trends were made on several resolution scales for each well log curve, e.g. one meter, two and four meter span for selecting the best resolution for observing trend line breaks. Constructed curves show that general trends that can be defined can be correlated between wells, especially for the youngest Pliocene-Pleistocene ones. Breaks in trend curves in some cases coincide with traditionally positioned well log markers. In addition, these breaks in some cases can be observed in seismic cross sections furthermore determining their applicability. Analysis showed the usefulness of some basic mathematics principles as a tool for division of subsurface, especially in the sedimentary environments in which traditional well log markers are not to be expected (small, dynamic basins), e.g. in Pliocene and Pleistocene sediments in Sava Depression.