Geological Approach Research Articles

Application of Stream Conductivity to Activity of Potential Large-Scale Landslide

Underclimate changes, extreme rainfall events can cause catastrophic sediment-related disasters such as large-scale landslides. To work on disaster prevention, the government has investigated the location of potential large-scale landslides by a geological and geomorphological approach. However, the activity of potential large-scale landslides has to rely on expensive on-site monitoring system, for example, observed drill hole of groundwater and underground displacement. Recently, the variation of stream electronic conductivity has been proposed to investigate the activity of large-scale landslide in Japan. Therefore, this study applied this concept in Taiwan. First, the temporal and spatial variations of stream electronic conductivity near the potential large-scale landslide have been surveyed. Accordingly, an interesting finding is that the spring water from the potential large-scale landslide can increase the concentration of chemical ion, and thus, the value of stream electronic conductivity increases. Second, the comparison of rainfall data, stream electronic conductivity, and ground surface displacement has been analyzed. There is a sound agreement between stream electronic conductivity and ground surface displacement. This result implied that stream electronic conductivity could be a possible index to monitoring the activity of potential large-scale landslides indirectly.

Considering Engineering Geology Input for Probabilistic Flood Hazard Assessments

ABSTRACT Probabilistic risk assessments were developed in the 1970s as consistent approaches to assessing public health protection by nuclear-facility safety measures. Risk-informed initiatives resulted in the characterization of processes that produce extreme events (hazards) independently from the detrimental effects of such events on people or environment from facility damage (risks), as well as quantifying uncertainties. For example, large dams are designed to perform without uncontrolled reservoir release under seismic motion with 1/10,000 annual frequency. Geologic inputs for seismic hazards include ground motion sources and site response. Probabilistic flood hazards analyses are emerging in response to uncertainty about the effects of climate change, aging flood control structures, and acceptance of probabilistic seismic hazard analyses. Geologic inputs for flood hazard have focused on paleoflood hydrology from slackwater deposits and boulder bars. Procedures are available for calculating probable maximum floods, produced from the most severe combination of meteorological and hydrologic conditions, but not for assessing annual frequencies of such events. Flood routing, the domain of hydrologists and hydraulic engineers, typically stipulates channel stability. What if channels erode during extreme floods, watershed slopes are susceptible to landslides, or landslides reduce channel cross sections? Hydrologists and hydraulic engineers evaluate flood flow and water elevation effects at facilities, whereas engineering geologists need to assess slope response and mobilization of debris under extreme precipitation. Keeping slope assessments consistent with probabilistic approaches is challenging. A real location provides a hypothetical example to illustrate selected aspects of the geological approach and to utilize the results of some available tools.

Pengetahuan Lokal Masyarakat Desa Cihanjuang, Kabupaten Sumedang tentang Bencana Longsor: Pendekatan Antropologi dan Geologi

This research aims at describing local knowledge about landslides among residents living in a landslide prone area; using Anthropological and Geological approach. In January 2021, a landslide occurred and killed 40 victims. This research uses qualitative and quantitative methods. Data were collected based on the Anthropology and Geology approach. Primary data were obtained through participatory observation, in-depth interviews, survey, and mapping using GIS technology. The results of this research indicate that geologically, the research location is prone to landslides. The residents have a lack of knowledge and experience about disasters, in particular landslides. Furthermore, they lack knowledge about the geological facts of the housing area. They trust the government and the developer who built the housing which they believe had considered the security of their housing.

Chemical and Isotopic Tracers for Characterization of the Groundwater in the Heterogeneous System: Case from Chichaoua-Imin’tanout (Morocco)

The geological and hydrogeological approach of the structure of the basin OuladBouSbaâ led to the definition of the geometry of the main aquifers. In general, the profiles show the complexity of the geological configuration. The filling of the depression of OuladBouSbaâ is from the Eo-Cretacian. At this level, the aquifer is recharged by direct water infiltration. The quaternary, Eocene, and Cenomanian-Turonian formations constitute the main aquifers. Horizontal as well as vertical heterogeneity lead to a higher diversification of aquifer characteristics. To define the origins and understand the groundwater flows in this complex zone, we used a multi-tracer approach with the analysis of major elements and the isotopes of δ2H and δ18O. The chemical composition is mainly governed by the interaction with the rock with low electrical conductivity except in areas around domestic landfills. Geochemical results analyzing groundwater in the Piper diagram show two distinct chemical facies: the sulfated calcium and magnesium, and the hyper-chloride calcium. The levels of δ18O range from −7.60 to −4.25 while those of δ2H vary between −53.07 and −27.03. Analyses of signature isotopes differentiate two groups. The first contains high levels of heavy isotopes (highest levels of δ2H and δ18O) having therefore been submitted to evaporation. The second with lower levels of δ2H and δ18O did not undergo evaporation. The first one belongs to the unconfined free aquifer while the second corresponds to the captive aquifer.

Archaeological and Geological Approaches in the Work on the Project “Materiality and ancient environmental knowledge reconstruction trough archaeological chemistry analytical techniques (RE:MATRIARCHES)”

The study discusses new approaches designed for the purposeful selection of archeological and geological sites and sample collection for analysis via archaeological chemistry techniques. The approaches discussed provide opportunities for coherent interpretation of analytical data in view of the project’s objectives: gaining fundamental knowledge of material culture in different archaeological periods as well as of people’s knowledge of the environment in ancient times.

Identification And Characterization Of Geoheritage Resources At Hulu Langat, Selangor

Identification and characterization of geodiversity for sites need more systematic approach for the purpose of conserving site with high geoheritage value. The present of igneous and metamorphic rock at Hulu Langat creates diversity in rock, features and geomorphological features includes hot spring, waterfall, hill and mountain that hold potential as a protected geosite of heritage value. Besides, the previous tin mining activities created by the contact metamorphism, left series of lakes and ponds while the nearby mountain is susceptible area as watershed that turn into dams around the area. Analysis on topographical maps, satellite image and aerial photograph interpretation aided in identification potential geosite based on geomorphological diversity. A total of 31 potential geosites with geological-scientific value have been identified in this study compare to 10 from the previous study. The potential geosite have been classified into rock diversity, natural landscape diversity and anthropogenic landscape diversity. Characterisation recognise 6 of these potential geosite are best example or tip location to illustrate the geological element, 4 of these geosites are the only occurrence of the geological element, 27 of the potential geosites are well preserved and 4 hold the scientific knowledge written in the international journal. The identification and characterisation of geoheritage resources are crucial steps before evaluation or assessment, ranking and conservation or development being propose, while strengthen the conservation geology approach.

Surface trace of the active Katrol Hill Fault and estimation of paleo-earthquake magnitude for seismic hazard, Western India

Estimation of seismogenic potential through geological studies of faults is an important step in seismic hazard evaluation and mitigation. We investigated the Katrol Hill Fault (KHF), an E-W trending and south dipping high angle reverse fault in the seismically active Kachchh Basin at the western continental margin of India. While several faults in the eastern part of the basin are presently seismically active, the KHF is the only fault in the entire basin that is shown to have produced three Late Quaternary surface faulting events. We illustrate here an integrated geological approach using field mapping, microscopic analysis (petrography and quartz surface textures using SEM) and shallow geophysical surveys using GPR for determining the precise surface trace of the active KHF. We also determined the displacement and slip-rate for each surface faulting event. Based on the Late Quaternary surface faulting parameters deduced, we calculated the moment magnitude (Mw) of the events using well established empirical relationships. These calculations yielded Mw values consistently ≥ 6.5. Our study shows that the KHF is capable of producing high magnitude earthquakes. We infer that these surface faulting events may be of relatively shallow focus as higher magnitude earthquakes in recent times along other faults in the basin, except the 1819 Allahbund earthquake, did not produce surface rupture. We recommend a revision of seismic hazard risk and mitigation strategies of the region as a consequence of our findings.

Geological Approach for Landfill Site Selection: A Case Study of Vršac Municipality, Serbia

One of the biggest problems of environmental protection in Serbia is landfills. It is often a case that the economic interests are predominant in the landfill sitting; thus, most landfills are not located according to standards. This study shows that detailed geological data assets combined with geographical modeling represents a reliable way to define and locate the landfill site. Geological evaluation is discussed in detail with regard to bedrock lithology, quaternary geology, geological structure, hydrogeology, surface runoff patterns, and topography. An approach combining geographical modeling and geology is presented for determining the sites suitable for landfill selection with respect to their geologic favorability. As opposed to numerous research papers on this topic, in the methodological procedure, special importance is devoted to the analysis of the geological criteria. In this way, it is significantly easier to determine the landfill area with the best characteristics due to geological structure and lithology which unequivocally and precisely indicates inadequate territories for candidate sites. The multicriteria decision analysis (MCDA) is based on geological criteria upgraded with road (primary, residential, secondary, and tertiary), settlements network, railway, airport, infrastructure, land use, hypsometry aquifer, wetland, and surface water. The score values are divided into four classes, i.e., restricted areas, suitable but avoid, suitable, and most suitable. Combining geographical modeling with geology led to the recognition of two locations to be most favorable for landfill site located in the most suitable area, which represents 25.3% of the study area.

Revised map of European aeolian deposits derived from soil texture data

European aeolian deposits have been mapped using the LUCAS topsoil texture database and the location, thickness and grain size mode of loess sections described in the literature have been compiled. The map, in fairly good agreement with those based on a classical geological approach, has the advantage of being of equal precision for the whole study area and makes it possible to highlight grain size gradients. It shows three main types of aeolian systems, i.e. systems associated with ice sheets (FIS, BIIS, AIS) and the rivers they feed, continental systems related to the erosion of sedimentary rocks, and coastal systems. Each aeolian system is comprised of a band of coversands of varying extent close to the sources and bands of sandy loess and loess away from the sources. The thickness of loess is highly variable throughout Europe. The areas of greatest accumulation are associated with the rivers draining the AIS (Rhine, Danube, Rhône). The Middle Danube, which combines sources of glacial origin (AIS) and local sources, constitutes the main accumulation area in Europe. Conversely, continental and coastal systems generated only limited loess cover. The latitudinal gradient of vegetation probably played an important role in loess sedimentation during the LGM. Weak interference between particle transport and vegetation (periglacial desert in the sand belt, cryptogamic crusts and steppe in the north European loess belt) allowed for particle sorting through aeolian transport to develop. The loess band is extensive in low-relief areas and is typified by a low sand content. In southern Europe, on the other hand, the capture of saltating and suspended particles by the shrubby steppe vegetation led to the dominant accumulation of sandy loess near sources.

Current and Foreseen Tungsten Production in Portugal, and the Need of Safeguarding the Access to Relevant Known Resources

The economic and strategic importance of tungsten is widely recognized, but several concerns exist on its stable future supply. Portugal is one of the main tungsten producers in Europe, having generated ≈121 kt of contained tungsten in mineral concentrates from 1910 to 2020, i.e., ≈3.3% of the global production documented for the same time period. Since the early nineties, tungsten mining in Portugal is confined to the Panasqueira deposit which accounts for 79% of the country reserves (≈5.4 kt). However, according to the performed Generalized Verhulst and Richards curve-fitting forecasts, there is a significant future potential for increasing production in Portugal due to the low (<2%) depletion rates of the remaining known tungsten resources (≈141 kt). This projected growth is not necessarily guaranteed, depending on many unpredictable economic, technological, and political factors, besides appropriate social consents. Even so, a prudent land-use planning oriented to long-term needs should avoid the sterilization of the most relevant tungsten resources so far identified in the country. These are resources of “public importance”, as objectively demonstrated with a weighed multi-dimensional (geological, economic, environmental, and social) approach. Safeguarding the access to these resources does not implicate more than ≈6% of the Portugal mainland territory. The joint interpretation of results independently gathered for tungsten production forecasts and for the definition of areas hosting tungsten resources of public importance, provides additional support to political decisions on the urgent need to reconcile mineral exploration surveys and mining with other land uses.

Species criteria in palaeontology and ichnology and the possibilities of using ichnofossils in geology

Paleontology is a science between biology and geology thus paleontologists use both biological and geological approaches to solve different kinds of problems. One of the main issues for paleontologist is the use of species criteria and species identification. The fossil record shows evidence of evolution of separate phyla and the biosphere in general. A significant part of the biosphere is represented by soft-body animals. The marks of activities different animals have appeared in the fossil record at least from rocks of Ediacaran to modern age. They could be imprints of “sitting” or moving tracks (of invertebrates or vertebrates), evidence of birth (for instance, egg fragments), crawling traces of molluscs, etc. There are a plenty of issues regarding the identification of the nature of ichnofossils. Sometimes it is possible to identify animal species that left their traces or imprints. We observe ichnofossils on the surface and inside sedimentary rocks, but their identification is often impossible. Therefore, an artificial nomenclature is used for the naming of “species” of ichnofossils. Ichnofossils of different age and from various facial conditions are investigated on all continents. Ichnology as a relatively new branch of geology is developing due to the use of modern technological approaches.

Seawater intrusion prone areas around Yogyakarta International Airport: a geological approach

Construction of Yogyakarta International Airport on Kulonprogo coastal areas can threaten the groundwater quality because it can cause seawater intrusion. The method in this study is by using a literature review. The purpose of this review is to investigate seawater intrusion prone areas around Yogyakarta International Airport based on a geological approach. The geological approach associated with seawater intrusion in the study site is a lithological characteristic. A lithological characteristic discussed in this study is the origin of the sand on Kulonprogo beach where the Yogyakarta International Airport is located. The elements used in the seawater intrusion test parameters are Na+, Ca2+, K+, Mg2+, CO3 2−, HCO3 −, Cl− and SO4 2−. A rise in Cl− was reported as suggesting the intrusion of seawater into the groundwater. But if only see the value of one of those elements, it cannot indicate seawater intrusion occurs in that area. The high element’s contents can arrive from the solution or weathering the lithological. This study is preliminary research, to assess seawater intrusion in the study site, it is necessary to conduct a groundwater geochemical test in the future.

Origin, migration and secondary processes of oil and natural gas in the western part of the Polish Outer Carpathians: geochemical and geological approach

The origin, migration pathways, as well as the influence of secondary processes of oil and natural gas accumulated in lower Cretaceous to lower Miocene strata of the western part of the Polish Outer Carpathians (between Kraków and Pilzno towns) based on results of organic geochemical analyses are investigated in this paper. Oil and thermogenic hydrocarbon gases were generated mainly from type II kerogen, and type II and III kerogen mixed in various proportions. These kerogens mainly occur in the Oligocene Menilite beds of the Silesian and Dukla nappes. Oils were generated from early to late “oil window”. Secondary cracking was recorded in oils from Dukla nappe, other secondary processes including biodegradation, water washing and evaporative fractionation were also developed to a various extent in many oils. The most biodegraded oils occur in seep S-Li, and the most extensive water washing is observed in the oil from seep S-Sa/1. The evaporative fractionation processes most significantly occur in the selected deepest parts of the multi-horizontal Biecz field. Hydrocarbon gases originated during both microbial and thermogenic processes of organic matter transformation. Natural gas has not been subjected to biodegradation processes. Carbon dioxide is derived from both microbial and thermogenic decomposition processes of organic matter and was generated together with hydrocarbon gases.

Behaviour of the oyster Rhynchostreon suborbiculatum assemblages in a Cenomanian-Turonian river dominated marginal-marine environment: multidisciplinary study from the Pieniny Klippen Belt (Western Carpathians, Slovakia)

ABSTRACT The tens of metres thick shell accumulations within the Cenomanian-Turonian strata of Western Carpathians enabled a complex study of ecological and geochemical proxies in relation to behavioural patterns of oyster Rhynchostreon suborbiculatum. Integration of geological and palaeobiological approaches enabled comparisons between one of the most famous fossil oyster species and several Recent bivalves. The analysis of grain size (Qz) and major oxides, together with taphonomic and population analysis, reveals a high-energy marginal-marine environment in the sedimentation area of the Orlové Sandstone. The life conditions of the association of bivalves, gastropods and polychaetes were influenced by the fluctuating influx of freshwater due to climatic changes that occurred during a dynamic period of the Late Cretaceous. A shift in the prominent control of biological production caused a massive increase in α-diversity, in conjunction with a change in the trophic structure of the studied system. The ecological responses of organismal association were also analogous to Recent representatives inhabiting marginal-marine environments. Size and allometric analyses of oysters forming monospecific assemblages show that their high density correlates with smaller shell sizes, indicating that intraspecific competition for food and space most intensified at times of the lowest salinity.

VAN BÖLGESİNDEKİ URARTU MERKEZLERİNDE KULLANILAN KAYAÇLARA İLİŞKİN PETROGRAFİK GÖZLEMLER

Van and its vicinity have been a prominent region with settlements recording many civilizations since the earliest periods in history. The most stunning remains of civilizations in this region belong to the Urartian Kingdom, which was established in the centre of Van from the middle of the 9th century BC. The capital city of the Urartian Kingdom was Tushpa (Van Castle), which was established on the Van Castle rock cliffs rising on the eastern shore of Lake Van. In addition to Tushpa, the capital of the Kingdom of Urartu, the architectural remains of many castles, urban settlements, and other architectural structures, including dams and water canals, are extensively observed in the eastern part of Lake Van. Considering the geological structure of this central region, it appears that the Kingdom’s settlements and architectural structures were founded on the Van formation, which consists of Bitlis Metamorphics, Upper Cretaceous Ophiolites and Tertiary deep-sea sediments that form the basement rocks in the region. This study was carried out to determine petrographic characteristics and classify rock types of natural stones used as building materials in Van Castle, Çavuştepe, Ayanis, Toprakkale, Zivistan, Keçikıran Castle, Körzüt Castle and Menua Canal belonging to the Urartian Kingdom. A secondary purpose was to use a geological approach to determine the quarries from which they were extracted. For this purpose, representative natural stone samples were taken from the architectural structures and their remains in the settlement centres of Urartian Kingdom in order to prepare rock thin sections of natural stone samples. The thin sections were examined under polarising petrographic microscope to determine petrographic features and classify the rock types. When the architectural building groups in Urartian settlements are examined, different natural stones were mostly used as building materials. The rock types of these natural stones used in construction of these structures are generally classified under two main groups as igneous and sedimentary origin. Sedimentary rock types such as limestone, travertine and sandstone were preferred as the main building material in settlement centres around the Lake Van Basin. Additionally, igneous rocks types such as gabbro, basalt, andesite and serpentinite were preferred more intensely in centres which are located around the north and western part of Lake Van. At the point of determining the sources of rock types used as natural stone building materials in the Urartian centres, it was concluded that Urartu primarily supplied those materials from the nearest quarry sites. The use of this material is also possible especially from rocky or other nearby areas on which the structure was built. However, in line with the materials used in cuneiform inscriptions and monumental architectural structures such as temples, etc, the supply of building materials was also provided by distant sources. Considering the geology of the region, it is suggested that essential findings were obtained showing that igneous rocks were brought from the areas north and west of Lake Van, while sedimentary rocks are represented by limestones from the southern part of Lake Erçek, and travertine rocks from quarries in the Edremit region.

Arsenic health risk studies in Uruguay with a Medical Geology approach: advantages and difficulties

In Uruguay safe drinking water is supplied to 94% of the population by a state company (OSE) and 28% is provided from groundwater sources. Geogenic Arsenic. Health risks through groundwater is a very recent issue of concern, regarding all international scientific evidence of several adverse effects associated with low levels (As>20 ug/L).We discuss the advantages of our research studies with a Medical Geology approach, to evaluate the influence of geological factors in the geographical distribution of health problems associated with arsenic exposure, and to highlight the main difficulties found in the process. This approach provides the tools for overlaying local geochemical data and arsenic water levels with disease registry data retrospectively, to potentially identify the possibility that the water consuming population, will develop a particular type of disease over time.We assess available geochemical data and As levels, provided by OSE and epidemiological data available from the National Atlas of Cancer prevalence that were geo-referred in the areas where arsenic data in water were available. We carried out a cross -over treatment data, to evaluate possible failures or deficiencies for their further analysis and correlation, finding several lacking records regarding environmental factors and/or drinking water sources. However, we could get distribution maps with refined data of arsenic levels, contrasted with the incidence data of cancer types associated with arsenic (lung cancer, bladder, melanoma, nonmelanoma skin, liver and kidney), for men and women respectively, finding some interesting correlations.Overlapping the Uruguayan cancer atlas data with As levels in wells can be a potential tool to estimate the contribution of As, to the incidence of cancer, though the retrospective data provided presented several difficulties and inconsistencies. We highlight the relevance of developing an interinstitutional and multidisciplinary common framework.

Exploring a social geology approach in eastern Indonesia: What are mining territories?

In this paper we suggest it is essential for development planners to utilize a social geology approach in making decisions on mining concessions. This is especially so in newly decentralizing democracies, such as Indonesia, where political decisions on natural resource extraction are often subject to accusations of corruption. We investigate several sites in different provinces in eastern Indonesia, where social consequences are constrained by geology and technology for mining minerals. On Flores Island, in the East Nusa Tenggara province, manganese is found as volcanic-hosted manganese layers, requiring heavy machinery from large mining companies, while in the same province, on Timor Island, sedimentary-hosted manganese, found in softer soils, can be mined by local communities. Political decentralization, fears of environmental destruction, and concerns over mining concessions resulted in resistance growing in the province, especially where companies mine without much benefit felt by local communities. We compare mining in East Nusa Tenggara province with mining in Sulawesi, long known for nickel and gold, where small-scale gold mining boomed in the past decade. We argue taking a social geology approach is the only way to fully understand mineral resources and to develop effective, efficient, and safe policies for the benefit of local and regional actors.

Origin of hydrocarbon and noble gases, carbon dioxide and molecular nitrogen in the Miocene strata of the eastern part of the Polish Carpathian Foredeep: Isotopic and geological approach

Fifteen natural gas samples were collected from the autochthonous Miocene strata between Dębica and Przemyśl towns in the eastern sector of the Polish Carpathian Foredeep. The samples were analysed for the molecular and stable isotope compositions of carbon (δ13C in CH4, C2H6, C3H8, i-C4H10, n-C4H10 and CO2), hydrogen (δ2H in CH4, C2H6 and C3H8), nitrogen (δ15N in N2), and all stable isotopes of noble gases (He, Ne, Ar, Kr and Xe) in order to reveal the origin and migration pathway of these gases. Methane concentrations usually exceeded 90 vol%. Methane was mainly generated by microbial carbon dioxide reduction. The rhythmic and cyclic deposition of clays, muds and sands in the Miocene marine basin facilitated and intensified microbial processes. Microbial ethane can be produced by methanogenic Archaea from acetate via reduction. Ethane partly contains a minor component generated from early mature thermogenic process. Propane and butanes were also generated thermogenically. The hydrocarbon gases in the Miocene horizons IIA and IIIA of the Góra Ropczycka field were generated at higher maturity thermogenic process than the rest of the analysed Miocene gases probably from the Middle Jurassic type III kerogen. They migrated to the Miocene horizons from the underlying Upper Jurassic horizon IV of the same field along a fault. Carbon dioxide of the analysed Miocene gases was mainly generated by primary microbial processes. Moreover, the total carbon constrained in the analysed Miocene gases from 0.1 to 6 wt% contained mantle-derived carbon, and thus carbon dioxide mantle component. Molecular nitrogen was mainly generated during low-temperature thermal transformation of organic matter. It might also involve a relatively insignificant component released from NH4-rich illites of the clayey facies of Miocene strata and an atmospheric component delivered by recharge of air-saturated seawater to the reservoir. Inorganic fluid supply from greater lithospheric depth would not be responsible for the promotion of thermal transformation of organic matter. Molecular nitrogen from Miocene horizons in the Góra Ropczycka field was generated during the thermal transformation of organic matter of higher maturity than the rest of Miocene gases, and migrated from the Upper Jurassic horizon along a fault. Helium is dominated by its radiogenic component, with a minor contribution from the mantle. The almost constant mixing ratios of the two helium components in the natural gases from Miocene horizons of various depths suggest that He migrated from a common inorganic deep-seated source in the lithosphere. The other noble gases are dominated by atmospheric components delivered to the hydrocarbon reservoirs by recharge of air-saturated seawater, with minor nucleogenic 21Ne, radiogenic 40Ar, and sedimentary Kr and Xe contributions. The atmospheric component is isotopically fractionated for Ne, and elementally fractionated with various degrees. The ratios of radiogenic 4He to nucleogenic 21Ne or radiogenic 40Ar are higher than the crustal production ratios, suggesting fractionation during thermal release from their host minerals and/or phase related fractionation during their transport to the gas reservoirs. The striking similarity in noble gas isotopic/elemental ratios of the Góra Ropczycka gas from the Miocene horizon IIIA to the nearby reservoir in Mesozoic strata is consistent with gas migration along a fault system.

A comparison of fuzzy logic and TOPSIS methods for landfill site selection according to field visits, engineering geology approach and geotechnical experiments (case study: Rudbar County, Iran).

The present study evaluated and selected the best location among susceptible landfill sites in Rudbar County using 27 criteria, as the maximum effective criteria, in the decision-making process. The emergence and comparison between the two methods of fuzzy and Technique for Order of Preference by Similarity to Ideal Solution (TOPSIS) with an engineering-geological approach have been conducted to obtain the best results. In this regard, inappropriate regions for landfill construction have been restricted after the conflation of two maps based on the restriction criteria. Then, the direction of prevailing winds and proper area for landfill construction was investigated for a 20-year perspective, and the regions that had more than 35-hectare area and were not located in the direction of the prevailing winds have been identified as responsive sites for landfill construction. Ultimately, selected susceptible regions were prioritized separately based on the TOPSIS and fuzzy methods. To ascertain the accuracy of the results and the reality of the resulted models, complementary field studies, geotechnical digging, and engineering-geological experiments have been used as verification parameters. According to the results of the verification, the fuzzy model having maximum matches with the verified data has been suggested for prioritizing susceptible regions.

Origin and migration of oil and natural gas in the central part of the Ukrainian outer Carpathians: Geochemical and geological approach

The generation and migration processes, as well as the influence of secondary processes, on oil and natural gas accumulated in Lower Cretaceous–lower Miocene strata of the central part of the Ukrainian outer Carpathians are discussed. Type II and II/III kerogens from the Oligocene–lower Menilite beds of the Boryslav-Pokuttya nappe generated oil and natural gas mainly during the middle stage of the oil window. These hydrocarbons accumulated in the fields of the Boryslav-Pokuttya and Skiba nappes. Water washing is the dominant secondary process occurring in many accumulations, regardless of reservoir rock, whereas biodegradation is insignificant and is clearly evident only in natural gas from one seep in the abandoned Starunia ozocerite mine. All hydrocarbon gases are thermogenic and were generated from mixed organic matter containing various proportions of type II and III kerogens. Only one natural gas accumulation in the Pivnichna Dolyna field contains some microbial hydrocarbon contribution. Carbon dioxide mainly originated from thermogenic kerogen decarboxylation and sporadically from microbial processes. Molecular nitrogen was mainly generated during low-temperature thermal transformation of organic matter and could also partly originate from NH4-rich illites of the clayey facies of the Oligocene–lower Miocene Menilite beds. The integration of the geochemical data with geological setting and maturation history of source rocks enabled us to reconstruct hydrocarbon migration paths, revealing the complicated trap-filling process.