Zone Of Basin Research Articles

Spatiotemporal distribution and attribution of carbon sequestration in karst rocky desertification land in southern China

<p>To mitigate the intensification of desertification and land degradation in karst areas of southern China, since the late 1990s, the Chinese government has implemented a series of ecological restoration projects. In the past couple of decades, the carbon sequestration potential of karst rocky desertification land increased significantly. However, few studies have explored the characteristics and driving mechanisms of carbon sequestration in karst areas. This study aimed to quantify the spatiotemporal patterns, trends, and drivers of carbon sequestration in the Huajiang River Basin, a typical karst basin, in southern China during 2000-2020 and its five geographic zones via the Integrated Valuation of Ecosystem Services and Tradeoffs (InVEST) model. The five zones of the karst basin exhibited the following characteristics: (I) good natural background condition with positive feedback human intervention; (II) poor natural background condition with increased negative and decreased positive feedback human interventions; (III) poor natural background condition with increased positive and decreased negative feedback human interventions; (IV) non-karst land; and (V) poor natural background condition with no significant positive and negative feedback human interventions and with heavy reliance on natural ecosystem recovery. The results were four-fold. First, the Huajiang River Basin showed a significant increasing trend of carbon sequestration. The spatiotemporal variation of carbon sequestration significantly differed among the five zones (Ⅴ > Ⅲ > Ⅳ > Ⅱ > Ⅰ). The stability of carbon sequestration was lowest in zone III. Second, a 20-y<span style="font-family: 'Times New Roman';">ear</span> land-use/cover change directly affected the level of carbon sequestration. The conversion of cropland, grassland, and woodland to shrubland was the main reason for the increased carbon sequestration in zone I. Third, carbon sequestration was negatively correlated with the desertification level of karst rocky areas. The spatial distributions of moderate, serious, and extremely strong desertification levels in zone II showed an increasing trend. Zones I, III, and V exhibited no significant desertification. Finally, the integrated ecological management against desertification increased carbon sequestration. Negative feedback human interventions (e.g., quarrying) exerted a significant disturbing impact on carbon sequestration that needs to be addressed in the formulation of management practices.</p>

Hydrochemical Characteristics and Ion Sources of Soil-Soluble Salt in the Water-Level Fluctuation Zone of the Lower Jinsha River Basin

The water-level fluctuation zone of the lower Jinsha River Basin is a fragile ecosystem with limited water resources in the southwest of China. Soil water is critical for maintaining ecological balance and promoting the healthy development of animals and plants in this region. In this study, eight typical soil profiles were monitored for hydrochemistry in soil-soluble salt from upstream to downstream of the lower Jinsha River Basin. The results show that the soil water content was low and had a negative correlation coefficient with major ions in the soil-soluble phase. The soil-soluble salt is slightly alkaline, and Ca2+, Na+, SO42−, and HCO3− are important components for ions in a soluble phase. Major ions in soluble salt originate from various sources, including precipitation, anthropogenic input, silicate weathering, and carbonate weathering, and the contribution rates from each end member were 0.7%, 45.1%, 25.2%, and 29%, respectively. The ion composition in surface soil soluble salt is mainly influenced by precipitation and human activities, while the ions in the 0–50 cm soil layer originate from the precipitation input and water-rock interaction. In addition, rock weathering is a vital process for releasing ions into soil-soluble salt from 50 to 100 cm soil layer. Our findings provide important references for ion sources and the eco-hydrological process in limited water resources in the water-level fluctuation zone of the lower Jinsha River Basin.

PLACER DEPOSITS OF DIAMONDS AND THEIR FORMATION CONDITIONS

This article reviews information from published papers and studies by the authors about placer diamond deposits. Original data were obtained in result of field and laboratory-analytical work carried out in various countries of Africa and South America. The main types of placer diamond deposits – fluvial, fluvioglacial, eolian, and man-made – have been considered and characterized. The main attention is given to fluvial continental placers, which are the most diverse, well-studied and have the greatest industrial importance. Primary, secondary and mixed deposits are distinguished according to the method of feeding; short, moderate and long transport deposits – according to the distance of the diamond-bearing material movement. It is noted that although the short transport placers (deluvial-proluvial and beds of short watercourses) have not industrial value, they are very informative for the searching for root sources. It is important to reliably diagnose these deposits by lithological-facies and mineralogical features during prospecting works. The concepts about the conditions for the formation of diamond placers in various landscape and geological conditions are developed and clarified. Alluvial-proluvial-lacustrine and proluvial-lacustrine types of placers studied in Yakutia and Brazil are characterized in detail. Their characteristic feature is that their productive strata, being re-deposited products of crustal weathering, themselves underwent a hypergenic change at the place of occurrence, which significantly masks the primary conditions of formation. Continental alluvial redeposition and long transport placers, as well as marine, yield the most high-quality expensive diamonds, the average value of which can reach $300–400 per carat. Often, such placers are formed due to the erosion of ancient Proterozoic placers, which belong to the category of fossils. The article summarizes the genetic and morphological types of diamond placers in the form of a principle diagram of the distribution of sedimentary reservoirs of kimberlite minerals. The landscape-dynamic zones of sedimentation are highlighted. A classification scheme of sedimentary reservoirs containing diamond placers has been developed. Continental, transitional and marine environments are distinguished, with further detalization of sedimentation environments – peneplain, alluvial-lacustrine accumulative plain, alluvial-deltaic plain and shelf zones of sea basins. It is shown that the formation of valley placers, their internal structure, thickness, granulometric composition and diamond content of alluvium are influenced by the dynamic phases of the formation of annual valleys. Visualization of the mutual relationship of different morpho-genetic types of placer diamond deposits is given.

Delineation of groundwater potential zones using remotely sensed data and GIS-based analytical hierarchy process: Insights from the Geba river basin in Tigray, Northern Ethiopia

Study regionThe study was undertaken in the Geba Drainage Basin, major tributary of the Tekeze Drainage Basin in Northern Ethiopia. Study focusThe objective of this study is to identify the groundwater potential zones of Northern Ethiopia's Geba Drainage Basin. Nine groundwater indicators were used as inputs, including lithology, geomorphology, lineament density, drainage density, slope, elevation, land use and land cover, rainfall, and soil. According to their relative influence on groundwater potentiality, the thematic layers and their classes were assigned appropriate weights based on Saaty's 1–9 judgment scale. The assigned weights were then normalized using an Eigen vector-based Analytical Hierarchy process. By superimposing all the normalized layers in the GIS environment, a groundwater potential map was developed. New hydrological insights for the regionFive distinct groundwater potential zones—very good, good, moderate, poor, and very poor were found in the study area. The areal distribution showed that majority of the area (45%) fell within the poor groundwater potential zone. The groundwater potential zones of moderate, very poor, good, and very good cover approximately 27%, 12%, 10%, and 6% of the total area, respectively. The results were compared to the groundwater yield of boreholes collected from the study area. The validation analysis revealed a 72% similarity, which is representative. The employed method is therefore a reasonable option for groundwater development in the Geba Drainage Basin.

Provenance and paleoclimate of Middle Permian Tavantolgoi formation sandstones in Baruunnaran coal deposit, southern Mongolia

Baruunnaran coal deposit is located in southern Mongolia; belongs to Tavantolgoi coal zone of South Gobi Basin (Bat-Erdene, 1992). Coal seams are hosted by Middle Permian Tavantolgoi Formation which is subdivided into lower and upper member, based on lithological characteristics. Ten core samples, consisting of sandstones were collected from exploration drill holes. 
 Sandstones from Middle Permian Tavantolgoi Formation in Baruunnaran coal deposit are investigated for unravel their provenance and paleoclimate conditions andtectonic settings. Detrital modes of sandstones in lower member are characterized as slightly high amount of mineral grains (quartz and feldspar) and slightly low amount of lithic fragments (litharenite, feldspathic litharenite and lithic arkose) comparing to sandstones from upper member (litharenite and lithic arkose). Provenance study of sandstones are shown signature of recycled orogens and mixed orogenic sands. Whereas, paleoclimate condition of sandstones from lower and upper members are interpreted as they were deposited in semi humid and arid environments, respectively.

Genetic diversity and structure of Callosobruchus maculatus populations in the different agro-ecological zones of Senegal

The objective of this study is to determine the diversity and genetic structure of cowpea weevil populations in the different agro-ecological zones of Senegal. Thus, to achieve this objective, individuals of Callosobruchus maculatus from localities in each zone were used, after sampling and massive breeding. The sequenced gene is Cyt-B. The results showed high haplotypic diversity (0.901 ±0.00033) and low nucleotide diversity (0.010 ±0.0000003). These diversities studied by agro-ecological zone show that the Casamance zone has the greatest haplotypic diversity (0.901; P>0.05) while the eastern Senegal zone has the lowest value (0.439; P>0.05). The nucleotide diversity is lower in the Sylvo-pastoral zone (0.00112; P<0.05) and higher in the Casamance zone (0.01052; P<0.05). The genetic structuring shows that the Senegal River Valley-eastern Senegal zone couple is more differentiated [FST(Fixation index)]=0.70687; P<0.05) and the Casamance-Groundnut Basin zone couple is less differentiated (FST=0.21248; P<0.05). The greatest genetic distance was found between the Sylvo-pastoral zone and the River Valley and the smallest between the eastern Senegal zone and the River Valley. However, a significant genetic variation within the populations was noted (64.93%). Overall we have a low level of diversity and weakly structured populations except those of Tamba and Fouta. A slight influence of the zones was also noted.

Living with Floods Using State-of-the-Art and Geospatial Techniques: Flood Mitigation Alternatives, Management Measures, and Policy Recommendations

Flood, a distinctive natural calamity, has occurred more frequently in the last few decades all over the world, which is often an unexpected and inevitable natural hazard, but the losses and damages can be managed and controlled by adopting effective measures. In recent times, flood hazard susceptibility mapping has become a prime concern in minimizing the worst impact of this global threat; but the nonlinear relationship between several flood causative factors and the dynamicity of risk levels makes it complicated and confronted with substantial challenges to reliable assessment. Therefore, we have considered SVM, RF, and ANN—three distinctive ML algorithms in the GIS platform—to delineate the flood hazard risk zones of the subtropical Kangsabati river basin, West Bengal, India; which experienced frequent flood events because of intense rainfall throughout the monsoon season. In our study, all adopted ML algorithms are more efficient in solving all the non-linear problems in flood hazard risk assessment; multi-collinearity analysis and Pearson’s correlation coefficient techniques have been used to identify the collinearity issues among all fifteen adopted flood causative factors. In this research, the predicted results are evaluated through six prominent and reliable statistical (“AUC-ROC, specificity, sensitivity, PPV, NPV, F-score”) and one graphical (Taylor diagram) technique and shows that ANN is the most reliable modeling approach followed by RF and SVM models. The values of AUC in the ANN model for the training and validation datasets are 0.901 and 0.891, respectively. The derived result states that about 7.54% and 10.41% of areas accordingly lie under the high and extremely high flood danger risk zones. Thus, this study can help the decision-makers in constructing the proper strategy at the regional and national levels to mitigate the flood hazard in a particular region. This type of information may be helpful to the various authorities to implement this outcome in various spheres of decision making. Apart from this, future researchers are also able to conduct their research byconsidering this methodology in flood susceptibility assessment.

INFLUENCE OF INVASIVE PLANT SPECIES ON SOIL PROPERTIES IN TROPICAL RIPARIAN ZONES

Riparian zones are highly productive biodiversity-rich transition areas. However, the invasion of exotic plant species depletes diversity and productivity, a severe global environmental concern as they alter ecosystem services. The analysis of spatio-temporal variations of soil nutrients in an invasive plant-impacted riparian zone is significant. This study was conducted in the riparian zones of a tropical river basin, Vamanapuram river basin (VRB), Southern Western Ghats, India, to analyse soil samples (total n= 60) from invaded (VR) and uninvaded (Control) areas for pH, Electrical Conductivity (EC), Organic Carbon (OC), available nitrogen (AN), available phosphorus (AP), and available potassium (AK). In general, comparing the invaded and control sites, changes were noticed in almost all the above physico-chemical parameters (except OC) at a significant level with high values in invaded soil sites mainly due to invasion. However, more studies are needed to differentiate the impacts within the system for a better understanding of invasive plant-soil interactions.

Using morphometric analysis for delineating groundwater potential zones of wadi Qena basin, Eastern Desert, Egypt.

Using morphometric analysis for delineating groundwater potential zones of wadi Qena basin, Eastern Desert, Egypt.

Application of Remote Sensing and GIS to Mapping Groundwater Potential Zones of Khazir River Basin, Northern Iraq

Application of Remote Sensing and GIS to Mapping Groundwater Potential Zones of Khazir River Basin, Northern Iraq

PROSPECTS OF SEARCHES AND PROBLEMS OF GAS DEVELOPMENT OF SEALED COLLECTORS OF THE DNIPRO-DONETSK DEPRESSION

The article considers the current problem of the hydrocarbon base of Ukraine. Materials that can serve as prerequisites for exploration and further development of gas from compacted reservoirs on the territory of the Dnieper-Donetsk graben are analyzed. In this article, the main parameters, that indicate the presence of gas in compacted reservoirs, are briefly considered. The data contain information about the features of the sedimentary section of the Paleozoic complex, namely, the geological structure of promising areas, the degree of catagenesis of gas-bearing rocks, the content of organic carbon in parent rocks, reservoir properties, and depths of gas-promising intervals. These data, taken from the results of drilling numerous wells, indicate a high probability of successful exploration for central basin gas within the axial zone of the Dnieper-Donetsk basin. As such deposits are difficult to extract, due to the complex geological structure of promising areas, a wide range of depths and, above all, poor reservoir properties of rocks containing gas, its development is impossible without the use of intensification methods. There are many chemical, thermal, mechanical technologies to cause the inflow of fluid from the reservoir, among which the hydraulic fracturing of the reservoir has become widespread. Modern methods of intensification are quite effective, but still remain imperfect, and therefore, there are some defects that cause certain complications in the development of the deposit. Тo cause the inflow of hydrocarbons from the compacted reservoirs, a foam gap of the formation is indicated, the use of which, in the opinion of the authors, is appropriate for deposits of this type. The article also points out the advantages of using a foam system compared to conventional fracturing and the need to improve some indicators of the foam system to its further use for compacted terrigenous reservoirs of the Dnieper-Donetsk avlakogen.

Seismic stratigraphy and attributes application for imaging a Lower Cretaceous deltaic system: Sukkur rift zone, Lower Indus Basin, Pakistan

This study is aimed at imaging the deltaic depositional sequences in the Sukkur Rift Zone (SRZ) of the Lower Indus Basin, Pakistan. The seismic sequence, back stripping, and thin-bed wedge modeling tools were applied to the gas field of the SRZ to develop the foundations for tectonics and sedimentary processes in the distribution of potential hydrocarbon reservoirs. The conventional seismic method does not have the capability to predict the quantitative aspects of deltaic systems. Five passive seismic sequences were utilized for mapping the sediments of the foreland margin within the Indian Plate. The subsidence curves showed that the tectonic activity had occurred between the Lower Cretaceous and Eocene depositional sequences. The maximum tectonic activity was observed during 50–70 Ma within the SRZ. The upper shoreface depositional system was modeled by a thin-bed wedge model at enhanced thicknesses of 52 m, 55 m, 56 m, 57 m, 58 m, and 61 m. Thin-bed wedge modeling has provided solid evidence and implications for the development of stratigraphic traps within the upper shoreface depositional system. The thin bed wedge model remained an accurate tool for the prediction of direct hydrocarbon indicator (DHI) within the tectonically-influenced depositional systems. Hence, the presented research work can be used as an analogue for the development of tectonically and stratigraphically stable fairways within the Asian Basins and similar geological settings.

Lake Changes during the Past Five Decades in Central East Asia: Links with Climate Change and Climate Future Forecasting

As one of the most important reservoirs of water in arid regions, lakes experience a series of complicated changes. However, the natural driving mechanisms behind such changes remain unclear. In this study, we collected data from 1333 lakes in the arid region of Central East Asia (CEA) to investigate the underlying natural causes of lake changes over the past five decades. The lakes were located within three different geomorphological zones: (I) Tibetan Plateau zone; (II) high mountain—basin zone; and (III) low mountain zone. Our results show that lakes as a whole in CEA exhibit a unique change trend, with an overall lake area increase of 7099 km2 (41%) and with heterogeneous spatial variations over the past five decades. The lake area increase was 6236 km2 (47%), 935 km2 (31%) and decrease was 72 km2 (~1%) in zones I, II, and III, respectively. The different geomorphological zones have influencing factors. In zones I and II, increased precipitation (including cloud water) and temperature rise (causing glacier, frozen soil, and snow melt) contributed to approximately 66% of the change in lake area; in zone III, changes in precipitation contributed to approximately 87% of the lake changes. Increased atmospheric circulation of water vapor caused by warming of the ocean surface appears to be the main driving factor of these changes; this is supported by future projection scenarios. From 2006 to 2098, temperature and precipitation will increase by 4.0–7.8 °C and 1.07 to 1.29 mm per day, respectively, under both the RCP4.5 and RCP8.5 scenarios. Notably, although the climate appears to have become more optimum for lakes in CEA at the interdecadal timescale, short timescale climatic events such as lake expansion will bring more extreme climate events, such as extreme high-temperature heat waves, which should be considered as a potential threat to lake ecology in the future.

PROSPECTS OF OIL AND GAS POTENTIAL OF THE JUNCTION ZONE OF THE NORTH-EAST OF THE PRECASPIAN BASIN AND THE SOUTHERN SEGMENT OF THE URAL FOLD SYSTEM (AKTOBE URALIAN FOREDEEP)

The identification of promising areas of exploration to develop the resource base of the Aktobe region is an urgent issue due to the gradual depletion of proven hydrocarbon reserves. The subsalt complex of the Aktobe Uralian Foreland is a prospective object, where prospecting and exploration work was carried out unevenly in the 1950s and 1980s, and most of the seismic survey data of 2004-2008 are low-informative. The subsalt complex of the studied area has been poorly studied by high resolution seismic studies and deep exploration drilling and previously belonged to the territories with low hydrocarbon potential. On the basis of the conducted research, data on the structural and tectonic zoning of the junction zone of the Precaspian basin and the southern segment of the Urals Foredeep are summarized, the geological structure of the Aktobe Uralian Foreland area is substantiated, favorable geochemical criteria of oil and gas potential are revealed.

Tectono-Thermal History of the Neoarchean Balehonnur Shear Zone, Western Dharwar Craton (Southern India)

Abstract A widely spaced Neoarchean shear zone network traverses the granite-greenstone terrains of the Western Dharwar craton (WDC). The NNW-SSE trending Balehonnur shear zone traverses the largest part of the preserved tilted Archean crustal ensemble in the Western Dharwar craton (WDC) from the amphibolite-granulite transition in the south to greenschist facies in the north and eventually concealed under Deccan lava flows. Published tectonic fabrics data and kinematic analysis, with our data reveal a sinistral sense of shearing that effectuate greenstone sequences, Tonalite-Trondhjemite-Granodiorite Gneisses (TTG), and Koppa granite as reflected in variable deformation and strain localization. A profound increase of strain towards the core of the shear zone in the ca. 2610 Ma Koppa granite is marked by a transition from weak foliation outside the shear zone through the development of C-S structures and C-prime fabrics, mylonite to ultramylonite. The mineral assemblages in the Koppa granite and adjoining greenstone indicate near peak P-T conditions of 1.2 Gpa, 775-800°C following a slow cooling path of 1.0 GPa and 650°C. Field-based tectonic fabrics data together with U-Pb zircon ages reveal that the Koppa granite emplaced along the contact zone of Shimoga-Bababudan basin ca. 2610 Ma, coinciding with the emplacement of ca. 2600 Ma Arsikere-Banavara, Pandavpura, and Chitradurga granites further east which mark the stabilization of WDC. Significant variation in major element oxide (SiO2 = 56-69 wt.%) together with high content of incompatible elements (REE, Nb, Zr, and Y) and high zircon crystallization temperatures (~1000°C) of Koppa granite suggests derivation by partial melting of composite sources involving enriched uppermost mantle and lower crust. The development of widely spaced shear zones is probably linked to the assembly of eastern and western blocks through westward convergence of hot oceanic lithosphere against already cratonized thick colder western block leading to the development of strain heterogeneities between greenstone and TTGs due to their different mineral assemblages leading to rheological contrast in the cratonic lithologies.

Salt diapirism in the eastern margin of the Pre-Caspian Basin: Insight from physical experiments

Since the 1950 s, salt diapirism has been shown to be closely related to hydrocarbon accumulation and has been a hot spot of research activity in structural and petroleum geology. Many salt structural, such as salt wall, roller, pillow, welt and anticline have been formed in the Pre-Caspian Basin during the post-Kungurian (Lower Permian) times. Meanwhile, mechanisms of salt structure deformation and the influence of the sub-salt strata on salt diapirism is still unclear. Based on seismic data and a geological model of the eastern margin of the Pre-Caspian Basin, physical simulation experiments of salt diapirism have been conceived. Performed to analyze, the dynamic process of salt structure deformation, and to clarify mechanisms of the salt diapirism and the relationships between the salt structures and the underlying strata. Differential loading seems to a principal mechanism accounting for sediment. The sedimentation rate of the overburden formations had a great impact on the salt structure forms and geometry. The physical experiments showed that: salt diapirism starts in the basin margin with progradation of sediments and then continues down-slope toward the basin center. The height and width of the salt structures are influenced by dip angle of the sub-salt. The larger-scale salt structures occurred in the inner basin zones, followed the central slope zone and the basin margin with a large dip angle.

Mélange, Flysch and Cliffs in the Pieniny Klippen Belt (Poland): An Overview

The Pieniny Klippen Belt (PKB) is located in the suture zone between the Central and Outer (Flysch) Carpathians. Its structure is an effect of prolonged processes of the Cretaceous–Miocene folding, thrusting and uplifting. In this zone, tectonic components of different ages and features, including strike-slip-bounded tectonic blocks, thrust units, as well as toe-thrusts and olistostromes, result in the present-day mélange characteristics of the PKB, where individual tectonic units are difficult to distinguish. In the PKB, both tectonic and sedimentary events triggered the mélange creation. The name “Klippen Belt” is derived from cliffs (German Klippen). These cliffs form harder, more erosion-resistant elements of the mélange, residing within less competent clastic deposits, sandstones, shales and marls that form flysch complexes. The cliffs often represent olistoliths, which glided down from elevated areas to the deeper basinal zones. Two olistostrome belts were distinguished. The older one resulted from subduction of the southern part of the Alpine Tethys, and the younger originated in response to the northward shift of the accretionary wedge. The other cliffs were placed within the surrounding clastic by tectonic deformational processes. The flower structure of the PKB was formed during the collision and strike-slip movement of the lithospheric plates. This structure is limited on both sides by deep-rooted faults. Several evolutionary stages could be distinguished in these areas. The rift-related stage is expressed by the opening of the Alpine Tethys that contains two major basins—Magura and Pieniny (Złatne) basins, separated by Czorsztyn Ridge. The reorganization of the Alpine Tethys basins and the development of the accretionary prism happened during the synorogenic stage. This process was initiated by the movement of the Central Carpathians. Thick flysch sequences with olistostromes were deposited in these basins. The Czorsztyn Ridge was destroyed during the late orogenic stages.

Network‐based biostratigraphy for the late Permian to mid‐Triassic Beaufort Group (Karoo Supergroup) in South Africa enhances biozone applicability and stratigraphic correlation

AbstractThe Permo‐Triassic vertebrate assemblage zones (AZs) of South Africa's Karoo Basin are a standard for local and global correlations. However, temporal, geographical and methodological limitations challenge the AZs reliability. We analyse a unique fossil dataset comprising 1408 occurrences of 115 species grouped into 19 stratigraphic bin intervals from the Cistecephalus, Daptocephalus, Lystrosaurus declivis and Cynognathus AZs. Using network science tools we compare six frameworks: Broom, Rubidge, Viglietti, Member, Formation, and one suggesting diachroneity of the Daptocephalus/Lystrosaurus AZ boundary (Gastaldo). Our results demonstrate that historical frameworks (Broom, Rubidge) still identify the Karoo AZs. No scheme supports the Cistecephalus AZ, and it probably comprises two discrete communities. The Lystrosaurus declivis AZ is traced across all frameworks, despite many shared species with the underlying Daptocephalus AZ, suggesting that the extinction event across this interval is not a statistical artefact. A community shift at the upper Katberg to lower Burgersdorp formations may indicate a depositional hiatus which has important implications for regional correlations, and Mesozoic ecosystem evolution. The Gastaldo model still identifies a Lystrosaurus and Daptocephalus AZ community shift, does not significantly improve recent AZ models (Viglietti), and highlights important issues with some AZ studies. Localized bed‐scale lithostratigraphy (sandstone datums), and singleton fossils cannot be used to reject the patterns shown by hundreds of fossils, and regional chronostratigraphic markers of the Karoo foreland basin. Metre‐level occurrence data suggests that 20–50 m sampling intervals capture Karoo AZs, unifying the use of metre‐level placements of singleton fossils to delineate biozone boundaries and make regional correlations.

Hydrological Forecasting under Climate Variability Using Modeling and Earth Observations in the Naryn River Basin, Kyrgyzstan

The availability of water resources in Central Asia depends greatly on snow accumulation in the mountains of Tien-Shan and Pamir. It is important to precisely forecast water availability as it is shared by several countries and has a transboundary context. The impact of climate change in this region requires improving the quality of hydrological forecasts in the Naryn river basin. This is especially true for the growing season due to the unpredictable climate behavior. A real-time monitoring and forecasting system based on hydrological watershed models is widely used for forecast monitoring. The study’s main objective is to simulate hydrological forecasts for three different hydrological stations (Uch-Terek, Naryn, and Big-Naryn) located in the Naryn river basin, the main water formation area of the Syrdarya River. We used the MODSNOW model to generate statistical forecast models. The model simulates the hydrological cycle using standard meteorological data, discharge data, and remote sensing data based on the MODIS snow cover area. As for the forecast at the monthly scale, the model considers the snow cover conditions at separate elevation zones. The operation of a watershed model includes the effects of climate change on river dynamics, especially snowfall and its melting processes in different altitude zones of the Naryn river basin. The linear regression models were produced for monthly and yearly hydrological forecasts. The linear regression shows R2 values of 0.81, 0.75, and 0.77 (Uch-Terek, Naryn, and Big-Naryn, respectively). The correlation between discharge and snow cover at various elevation zones was used to examine the relationship between snow cover and the elevation of the study. The best correlation was in May, June, and July for the elevation ranging from 1000–1500 m in station Uch-Terek, and 1500–3500 m in stations Naryn and Big-Naryn. The best correlation was in June: 0.87; 0.76; 0.84, and May for the elevation ranging from 1000–3500 m in station Uch-Terek, and 2000–3000 m in stations Naryn and Big-Naryn. Hydrological forecast modeling in this study aims to provide helpful information to improve our under-standing that the snow cover is the central aspect of water accumulation.

POTENTIAL SOURCE ROCKS EVALUATION FOR THE PRE-SALT COMPLEX OF THE EASTERN EDGE OF PRECASPIAN BASIN

Through basin analysis, the major tectonic stages and paleogeographic conditions of the formation of potential oil and gas source rocks of the subsalt complex of the eastern side zone of the Precaspian basin are considered. Prediction and localization of potential source rocks is critical for the Precaspian petroleum system understanding, both during petroleum play assessment at the prospecting and exploration stages. The generation and emigration potential of the oil and gas basin is determined not only by the concentration of the initial organic matter in the rock, but also by the type of kerogen. Based on Rock-Eval studies and comparative analysis with published biomarker data, the generation potential, genetic type and thermal maturity are analyzed depending on the age and structural relatedness of potential source rocks. A high generation potential has been established for the Lower Permian deposits, the occurrence of multiple generation foci controlled by the type and concentration of organic matter is predicted, which led to the formation of specific reservoirs of the "akzharite" type. The generation potential of the Visean-Bashkirian deposits is poor to average, catagenetic unconformities have been established within KT-II, KT-I, which indicates erosions, the total organic carbon (TOC) is 0.1-4%, the hydrogen index increases with depth, for samples enriched with TOC and with a content of S2 > 1, type II kerogen has been established, which it is an indicator of reducing marine environment. 2D basin modeling was performed in order to reconstruct the thermal evolution of potential source rocks and their thermal maturity and transformation ratio were modelled to determine the regional characteristics of hydrocarbon generation and migration. It is assumed that the formation and distribution area of the primary source rocks is associated with reducing conditions of the deep-sea shelf and continental slope and intensive subsidence in the Late Devonian-Lower Permian times. Conducting a comprehensive analysis of paleogeographic and paleotectonic conditions for the formation of potential source rocks is of key importance in the seismic interpretation and reconstruction of thermal history. 2D basin modeling was performed in order to reconstruct the thermal history of potential oil-producing strata and the degree of catagenetic maturity and the kerogen maturity index were estimated to determine the regional characteristics of hydrocarbon generation and migration.