Location Of Deposits Research Articles

საქართველოს რელიეფის მორფოსტრუქტურული ანალიზი

As a result of the morphostructural analysis of the relief of Georgia, a scheme of tectonic faults has been compiled, the validity of which has been reinforced by the study of space materials. The faults represent straight-line structures and create an orthogonal diagonal system grid. The scheme explains the morphology of many geological structures and geological outcrops, as well as the peculiarities of the location of mineral deposits.

РЕЗУЛЬТАТЫ ПРИМЕНЕНИЯ СТАТИСТИЧЕСКОГО МЕТОДА ДЛЯ ПРОГНОЗА НЕФТЕГАЗОНОСНОСТИ ТЕКТОНО-КОНЦЕНТРИЧЕСКИХ СТРУКТУР ДАЛЬНЕГО ВОСТОКА РОССИИ С ИСПОЛЬЗОВАНИЕМ ЭТАЛОННЫХ ТЕРРИТОРИЙ

he paper presents the results of using the statistical method to analyze geological and geophysical data measured within several tectonic-concentric structures in oil and gas-bearing regions in the Far East of the Russian Federation (depth of the Mohorovichi surface, depth of the the lithosphere bottom, values of geothermal energy). The distribution and values of some statistical parameters (histograms, distribution densities, probabilities, median and mean values) used for forecasting zones of hydrocarbon deposits location have been calculated. It was found that the most informative initial data used for statistical prediction of areas of location of oil and gas deposits are the presence of concentric zones at the depth of the Mohorovichich surface, and concentric inhomogeneites at the lower boundary of the lithosphere associated with the «root» structures of paleo-mantle plumes. Based on the calculated statistical parameters, four local tectonic-concentric structures promising for prospecting new oil and gas fields were identified.

3D X-ray computed tomography in the analyses of intraocular lenses explanted because of postoperative opacification.

To use X-ray computed tomography (CT) -which describes the acquisition and reconstruction of 2-dimensional X-ray transmission images to create a 3D representation of a specimen -in the analyses of intraocular lenses (IOLs) explanted because of optical opacification occurring postoperatively. John A. Moran Eye Center, and Utah Nanofab, University of Utah, Salt Lake City, Utah. Laboratory study. A hydrophilic acrylic and a silicone lens (the latter from an eye with asteroid hyalosis) explanted because of postoperative calcification, as well as a poly(methyl methacrylate) (PMMA) lens explanted because of snowflake degeneration underwent analysis under gross and light microscopy. Then, they were attached to an appropriate support and scanned under a Zeiss Xradia Versa X-ray microscope. After data acquisition, data segmentation was performed with a commercially available program to separate image data into components. Morphology, size/volume, and specific location of calcified deposits on the surface or within the substance of explanted IOLs could be demonstrated by X-ray CT within the entire volume of each lens with high contrast and resolution. The PMMA lens showed multiple spaces/fissures in relation to Nd:YAG pitting of the optic, and what appeared to be sheets of delaminated PMMA material at different levels within the optic substance. The key benefit of X-ray CT is that it can be performed without physically sectioning the specimen. This preliminary study demonstrates that this technology can be potentially useful in the imaging and analyses of explanted, opacified lenses.

Three-Dimensional Gravity Inversion Based on Attention Feature Fusion.

Three-dimensional gravity inversion is a process of obtaining the location, shape, and physical property parameters of underground anomaly sources using gravity anomaly data observed on the surface. In recent years, with the rapid development of data-driven methods, the application of deep learning (DL) to 3D gravity inversion has also attracted wide attention and achieved certain results. In this paper, based on the U-Net network, a three-dimensional gravity inversion method using an attention feature fusion mechanism is proposed. Using U-Net as the basic framework, the coarse-grained semantic features and fine-grained semantic features in the encoder and decoder are connected by long hops, and the global and local semantic features are aggregated through the attention feature fusion module, which avoids feature loss in the network training process. Compared with the inversion results of the U-Net network, the proposed method has a higher vertical resolution and effectively alleviates the influence of the skin effect on three-dimensional gravity inversion. Ablation experiments show that the attention feature fusion module is the key to improving the vertical resolution and prediction accuracy of inversion results. Noise experiments show that the inversion network in this study has a strong anti-noise ability and good generalization performance. The experimental results of the inversion network used in the prediction of the SAN Nicolas deposit in Mexico show that the inversion network can clearly predict the basic location and general shape of the sulfur deposit, and the results are in good agreement with the known geological data.

A global database of tsunami deposits

AbstractGeomorphic environments play a crucial role in influencing the preservation and characteristics of tsunami deposits. This paper introduces a global database of tsunami deposits, encompassing information on deposit locations, thematic data such as geomorphic environments and proxies and bibliographic details. Additionally, the database features maps incorporating environmental parameters and the precise locations of tsunami deposits. The primary utility of this database lies in assessing progress and identifying gaps in knowledge. It also involves analysing the relationship between environmental parameters and interpreting areas with varying probabilities of tsunami deposit preservation. The files are readily compatible with GIS software and can seamlessly integrate into spatial databases associated with tsunamis or other hazards. This contributes significantly to disaster risk management, enhancing preparedness and response efforts by providing a comprehensive historical dataset on tsunamis. Future applications of the database include the incorporation of modern deposits, boulders and new data from paleotsunami and historical studies. By enhancing data with thematic information, such as dating techniques and creating timelines, the database facilitates a more comprehensive understanding. The correlation between geomorphic environments and proxies aids in selecting sampling sites and identifying suitable proxies for analysis. Encouraging an open‐access approach, this database invites all interested researchers to include and modify additional information. The information compiled for this database serves multiple purposes: (1) assessing the global distribution of tsunami deposits; (2) identifying knowledge gaps in tsunami deposits; (3) guiding the selection of study areas for further research and finally; (4) enabling a meta‐analysis of the information gathered.

Advancing precision agriculture: domain-specific augmentations and robustness testing for convolutional neural networks in precision spraying evaluation

AbstractModern agriculture relies heavily on the precise application of chemicals such as fertilisers, herbicides, and pesticides, which directly affect both crop yield and environmental footprint. Therefore, it is crucial to assess the accuracy of precision sprayers regarding the spatial location of spray deposits. However, there is currently no fully automated evaluation method for this. In this study, we collected a novel dataset from a precision spot spraying system to enable us to classify and detect spray deposits on target weeds and non-target crops. We employed multiple deep convolutional backbones for this task; subsequently, we have proposed a robustness testing methodology for evaluation purposes. We experimented with two novel data augmentation techniques: subtraction and thresholding which enhanced the classification accuracy and robustness of the developed models. On average, across nine different tests and four distinct convolutional neural networks, subtraction improves robustness by 50.83%, and thresholding increases by 42.26% from a baseline. Additionally, we have presented the results from a novel weakly supervised object detection task using our dataset, establishing a baseline Intersection over Union score of 42.78%. Our proposed pipeline includes an explainable artificial intelligence stage and provides insights not only into the spatial location of the spray deposits but also into the specific filtering methods within that spatial location utilised for classification.

A nitrogen isotopic shift in fish otolith–bound organic matter during the Late Cretaceous

The nitrogen isotopes of the organic matter preserved in fossil fish otoliths (ear stones) are a promising tool for reconstructing past environmental changes. We analyzed the 15N/14N ratio (δ15N) of fossil otolith-bound organic matter in Late Cretaceous fish otoliths (of Eutawichthys maastrichtiensis, Eutawichthys zideki and Pterothrissus sp.) from three deposits along the US east coast, with two of Campanian (83.6 to 77.9 Ma) and one Maastrichtian (72.1 to 66 Ma) age. δ15N and N content were insensitive to cleaning protocol and the preservation state of otolith morphological features, and N content differences among taxa were consistent across deposits, pointing to a fossil-native origin for the organic matter. All three species showed an increase in otolith-bound organic matter δ15N of ~4‰ from Campanian to Maastrichtian. As to its cause, the similar change in distinct genera argues against changing trophic level, and modern field data argue against the different locations of the sedimentary deposits. Rather, the lower δ15N in the Campanian is best interpreted as an environmental signal at the regional scale or greater, and it may be a consequence of the warmer global climate. A similar decrease has been observed in foraminifera-bound δ15N during warm periods of the Cenozoic, reflecting decreased water column denitrification and thus contraction of the ocean's oxygen deficient zones (ODZs) under warm conditions. The same δ15N-climate correlation in Cretaceous otoliths raises the prospect of an ODZ-to-climate relationship that has been consistent over the last ~80 My, applying before and after the end-Cretaceous mass extinction and spanning changes in continental configuration.

Estimation of red clay soil in Kirkuk City using Satellite remote sensing data

The focus of this study is to generate maps of clay and clay mineral deposits in the Kirkuk, Bor, and Jambor structures using Landsat imagery. The authors utilized the band ratio (5/7) and band composite (3,4,5) techniques in their analysis. Fifty-two sites were selected as testing data to evaluate the accuracy of the generated map, which showed a correlation of 0.74. The study concludes that remote sensing techniques provide a cost-effective and accurate means to map the locations of clay and clay mineral deposits, offering an alternative to traditional mapping methods.

Holocene storminess dynamics in northwestern Ireland: Shifts in storm duration and frequency between the mid- and late Holocene

Substantial uncertainties exist regarding how future climate change will affect storminess (storm frequency and intensity) in Ireland and the United Kingdom (UK). Knowledge about spatiotemporal variations of past storminess gives us a better understanding of its mechanisms on centennial to millennial time scales, as well as the impact of external forcing on future storminess in climate models. Here, we present the oldest storm record to date from Ireland, covering the last 8000 years, reconstructed from the Roycarter Bog, a coastal blanket bog in north-western Ireland. The sequence was analysed for grain-size, chemical, mineral and organic molecular composition. The chronology was built on 11 AMS radiocarbon dates. The deposit characteristics, location and low inorganic content suggest aeolian transport of particles to the bog throughout the studied period. Cluster analysis of the grain-size frequency curves, along with the coarse to fine sand ratio, allowed the identification of eleven storm periods (cal yr BP): 6150–5500 (1); 4970–4130 (2); 4000 (3); 3490–3290 (4); 3230 (5); 2850–2590 (6); 2170–1920 (7); 1440 (8); 1225–890 (9); 620–470 (10); and 290–230 (11).During the mid-Holocene, the relative sea level was lower and the local beach sources located further away, giving a longer transport distance compared to the late Holocene. In the latter part of the mid-Holocene (6150–4130 cal yr BP), during the Holocene thermal maximum, increased storminess and wind strengths were inferred for north-western Ireland, manifested as two longer storm periods. During the late Holocene the storm frequency increased, and a greater number (9) of shorter storm periods were recorded. Comparison between our results and regional peat palaeostorm records from Scotland, north of our study site, showed an antiphase relationship between storminess in Ireland and Scotland during the latter part of the mid-Holocene, but mostly in-phase storminess over the last 3000 years. Taken together, enhanced wind strength and storminess were recorded during the warmer mid-Holocene, while an increased frequency of storm events occurred in the cooler late Holocene. Mid-Holocene storm periods occurred during locally wet periods, while most of the storm periods during late Holocene occurred during drier phases. Alternatively, the elevated mineral input during late Holocene promoted microbial activity and peat decomposition. The apparent variability in cyclicity and frequency between the mid- and late Holocene indicates that the processes governing storminess in the region shifted. This calls for further studies ahead, including climate modelling, to disentangle the complex processes governing storminess on millennial to centennial time scale.

Analysis of gravity anomaly data for identification of mineral distribution prospects in the Kuta Cot Glie area, Aceh Besar

Abstract Gravity anomaly data was analyzed using the gravity method to obtain variations in gravity values and to identify mineral distribution prospects in the Kuta Cot Glie area, Aceh Besar. The Scintrex CG-5 gravimeter instrument was used to measure gravity data. After being corrected and receiving complete Bouguer anomaly values, the variation in gravity values from the research location was shown to be in the range 75-126 mGal. There are two anomalies within gravity values that are higher and lower than the surroundings. The first one is the distribution of serpentine minerals (2.4 – 3.10 g/cm 3) with variations of 108-126 mGal. This serpentine mineral is located at the center of the research location with a total area of ± 67,500 m 2. The second anomaly is limonite mineral deposits (1.55-1.7 g/cm3) with variations in gravity values of 75-87 mGal. The limonite were found on the East and West sides of the location, with a distribution area of ±71,250 m 2. The mineral deposit of limonite is a result of weathering from serpentinite rocks, therefore, the location of limonite mineral deposits is lower than the location of serpentinite. These results are aligned with the geological conditions which is dominated by serpentinite ultramafic metamorphic rocks.

Crustal conductivity footprint of the Miocene porphyry copper polymetallic deposits in the Gangdese metallogenic belt, Tibetan Plateau

New evidence worldwide has linked the surface locations of mineral deposits and their crustal-scale electrical conductivity footprint. We examine the relationship between the Gangdese Miocene porphyry copper deposits, Tibetan Plateau, and the electrical conductivity signature from a three-dimensional model generated from 311 magnetotelluric measurements. The distribution of electrical resistivity throughout the crust and the conductance within the mid-lower crust (depth range of 25–70 km) is analyzed. The results clearly show that the large and ultra-large Miocene porphyry copper deposits coincide spatially with conductive zones and areas of very-high conductance (>10,000S) in the mid-lower crust. Computations are undertaken to determine the influence of water-bearing silicate melts and alkali-bearing (Na+ and K+) fluids on conductivity. Based on this, the bulk conductivity is interpretated to be caused by a system of alkali-rich volatile-rich partial melt. The alkali-rich volatile-rich magmatic-hydrothermal fluids facilitate the migration and concentration of metal ions originating in deep areas. The volumes necessary are much less than partial melt alone and can thus help to reconcile large conductivity variations with small seismic velocity variations. The electrical structure indicates the magma source area of anatexis in the lower crust, a multi-stage magmatic system with large mid-crustal and small upper-crustal magma reservoirs, and complex pathways related to rift zones. We determine that the conductive zones in the mid-lower crust have an influence on the development of the mineralization and the location of the mineral belt.

Numerical modeling of the mineralizing processes within the Shaxi porphyry-type Cu-Au deposit, Eastern China: Influence and restriction from physical and chemical characteristics of host rocks

The Shaxi porphyry-type Cu-Au deposit is located in the northwestern outer margin of the Luzong volcanic basin, which is situated in the Middle-Lower Yangtze River Metallogenic Belt (MLYRMB), Eastern China. It is a large porphyry-type Cu-Au deposit with confirmed copper resources exceeding 1 Mt and gold resources exceeding 40 tons. Previous studies have extensively investigated the genesis, controlling structures, geochemical characteristics, fluid evolution, alteration zone, and ages of mineralization and host rocks in this deposit. However, research on the influence of the physical and chemical properties of the host rocks on the mineralizing processes has not been explored in detail. This study employs the finite element method to apply numerical modeling of multiple physical and chemical fields, interlinking heat transfer, fluid flow, material migration, mineralization reaction, and their coupling with porosity and permeability of rock, to investigation of the influence of different porosities, permeabilities, and chemical properties of the host rocks on the mineralizing processes in the Shaxi deposit. The results show that the porosity and permeability of the host rocks play a significant role in the mineralization of porphyry-type systems. The different porosity and permeability of the intrusions and strata control the depth, the mineralization intensity, the morphology of the ore bodies, and the spatial location of the mineralization center. The chemical properties of the strata significantly restrict the mineralization intensity and horizontal spatial rather than affecting the depth of mineralization. Furthermore, the formation of skarn-type deposits may require a longer period of time than that of porphyry-type deposits under the same mineralization conditions and ore grade. This paper also indicates that the numerical modeling method employed in this study can be used to predict the mineralization depth and spatial location of deep concealed porphyry-type deposits, aiding research in deep-seated mineral exploration.

Equivalent density of calcium deposits – a new diagnostic pattern for atherocalcinosis

Objective. To assess the density of the calcified substrate of atherosclerotic plaques of the carotid arteries using data from the computed tomography of patients with multifocal atherosclerosis. Material and methods. In 251 patients with verified atherosclerosis of the coronary and carotid arteries, with a high prevalence of angina pectoris, a history of myocardial infarction and modifiable cardiovascular risk factors, multislice computed tomography (MSCT) of the carotid arteries was performed to assess the calcium index and determine the equivalent density of calcium deposits (EDCD). A morphological sub-study of the material from the removed atherosclerotic plaques was carried out using scanning electron microscopy (SEM) in 12 patients. Results. According to the MSCT data, we identified 5 main types of calcium deposit location in the thickness of the atherosclerotic plaque. We noted that totally calcified plaques were associated with carotid artery stenosis by more than 30 %. According to the SEM data, we identified 2 leading patterns: diffuse and compact types of microcalcification. There was a statistically significant association of a low level of EDCD with a diffuse type of calcification both in vivo (p=0.010) and ex vivo (p=0.008). Patients, having carotid artery EDCD less than 0.21 mg/mm3, reported a significantly higher incidence of type 2 diabetes mellitus (p=0.0001) and a history of stroke (p=0.021). When comparing the MSCT data on the calcium deposit density and their localization in the atherosclerotic plaque, we noted a statistically significant predominance of low EDCD with superficial calcification of the plaque (p=0.002). Conclusion. The use of a calculated indicator of the equivalent density of calcium deposits of the atherosclerotic substrate allows us to non-invasively obtain new data on the structure of plaques. The observed association of the superficial distribution of calcification with low calcification density according to the MSCT data may indicate potential plaque instability.

Enhancing Geological Understanding and Identifying Gold Anomalies in the Ailaoshan Orogen

AbstractThe Ailaoshan Orogen in the southeastern Tibet Plateau, situated between the Yangtze and Simao blocks, underwent a complex structural, magmatic, and metamorphic evolution resulting in different tectonic subzones with varying structural lineaments and elemental concentrations. These elements can conceal or reduce anomalies due to the mutual effect between different anomaly areas. Dividing the whole zone into subzones based on tectonic settings, ore cluster areas, or sample catchment basins (Scb), geochemical and structural anomalies associated with gold (Au) mineralization have been identified utilizing mean plus twice standard deviations (Mean + 2STD), factor analysis (FA), concentration‐area (C‐A) modeling of stream sediment geochemical data, and lineament density in both the Ailaoshan Orogen and the individual subzones. The FA in the divided 98 Scbs with 6 Scbs containing Au deposits can roughly ascertain unknown rock types, identify specific element associations of known rocks and discern the porphyry or skarn‐type Au mineralization. Compared with methods of Mean + 2STD and C‐A model of data in the whole orogen, which mistake the anomalies as background or act the background as anomalies, the combined methods of FA and C‐A in the separate subzones or Scbs works well in regional metallogenic potential analysis. Mapping of lineament densities with a 10‐km circle diameter is not suitable to locate Au deposits because of the delineated large areas of medium‐high lineament density. In contrast, the use of circle diameters of 1.3 km or 1.7 km in the ore cluster scale delineates areas with a higher concentration of lineament density, consistent with the locations of known Au deposits. By analyzing the map of faults and Au anomalies, two potential prospecting targets, Scbs 1 and 63 with a sandstone as a potential host rock for Au, have been identified in the Ailaoshan Orogen. The use of combined methods in the divided subzones proved to be more effective in improving geological understanding and identifying mineralization anomalies associated with Au, rather than analyzing the entire large area.

Lithospheric Structure and Melting Processes in Southeast Australia: New Constraints From Joint Probabilistic Inversions of 3D Magnetotelluric and Seismic Data

AbstractThe thermochemical structure of the lithosphere controls melting mechanisms in the mantle, as well as the location of volcanism and ore deposits. Obtaining reliable images of the lithosphere structure, and its complex interactions with the asthenosphere, requires the joint inversion of multiple data sets and their associated uncertainties. In particular, the combination of seismic velocity and electrical conductivity, along with proxies for bulk composition and elusive minor phases, represents a crucial step toward fully understanding large‐scale lithospheric structure and melting processes. We apply a novel probabilistic approach for joint inversions of 3D magnetotelluric and seismic data to image the lithosphere beneath southeast Australia. The results show a highly heterogeneous lithosphere with deep conductivity anomalies that correlate with the location of Cenozoic volcanism. In regions where the conductivities have been at odds with sub‐lithospheric temperatures and seismic velocities, we observe that the joint inversion provides conductivity values consistent with other observations. The results reveal a strong relationship between metasomatized regions in the mantle and (a) boundaries of geological provinces, elucidating the subduction‐accretion process in the region; (b) distribution of leucitite and basaltic magmatism; (c) independent geochemical data, and (d) a series of lithospheric steps which constitute areas prone to generating small‐scale instabilities in the asthenosphere. This scenario suggests that shear‐driven upwelling and edge‐driven convection are the primary mechanisms for melting in eastern Australia, contrary to the conventional notion of mantle plume activity. Our study presents an integrated lithospheric model for southeastern Australia and provides valuable insight into the mechanisms driving surface geological processes.

Institutional factors influencing productivity in medieval England: A case study of tin, lead and silver mining

AbstractThis paper fills a gap in recent literature on productivity and regional development by examining the determinants of productivity in primary industries in English regions during the Middle Ages. It provides a comprehensive review of relevant literature on the tin, lead and silver mining industries in Medieval England. Modern studies of productivity typically focus on technology, labour skills, unionization and regional economic infrastructure as key determinants of productivity growth and focus on high‐technology manufacturing industries This study of medieval mining, however, focuses on extractive industries in which advanced technologies played only a limited role. The paper shows that alternative factors contributed to the productivity of medieval mining including royal policy, the location of deposits and fluctuations in demand. Technology, investment in training and worker activism had, in contrast, little impact.

Palynology of Lake Motykino in the Holocene (Vologda region, Northwestern part of European Russia)

This work is dedicated to studying the dynamics of vegetation and natural-climatic conditions in the Mologo-Sheksninskaya lowland in the north of the East European Plain during the Holocene. Lake Motykino, located in the Darwin Nature Biosphere Reserve, was chosen as the research object due to its unique location and preservation of relic lake deposits. Radiocarbon dating and pollen analysis were conducted. The research results are presented in the form of a lithological description of the sediment column, stratigraphic analysis, and a pollen diagram divided into five local pollen zones, reflecting the succession of plant communities from periglacial landscapes in the Late Glacial to the formation of boreal forests in the Holocene. Analysis of pollen spectra allowed for the identification of key periods in the vegetation history of the region, from 13,300 cal BP to 400 cal BP, and to track changes in vegetation composition and peat formation processes.

Dual energy CT for the diagnosis of gout: Evaluating the optimal Hounsfield unit setting for dual energy processing

Rationale and objectivesDual-energy CT (DECT) plays an important role in the evaluation of gout based on its ability to identify monosodium urate (MSU) crystals. Post-processing of DECT includes selection of a minimum Hounsfield unit (HU) threshold, currently set at 150 HU. Adjustments to this setting will affect the amount of MSU that is identified, with lower thresholds identifying more true and false positive MSU. The purpose of this study is to assess the performance of several HU thresholds. Materials and methods134 DECTs were reprocessed with minimum HU thresholds set to 150, 140, 130, and 120 HU. Volume of MSU detected was compared across thresholds. Subsequently, readers reviewed 3D axial images from 109 cases at 150, 130, and 120 HU thresholds. For each case, the reader made a diagnosis of gout, rated their confidence, and reported the location of MSU deposits. ResultsMean MSU volume detected was as follows: 0.160 at 150, 0.205 at 140, 0.276 at 130, and 0.444 at 120 HU. Based on reader diagnosis, there was no significant difference in sensitivity for the diagnosis of gout between the 150 (68.8%), 130 (71.8%), and 120 (69.7%) HU thresholds (p = 0.653). Specificity was higher at 150 HU (65.4%) than at 130 (58.4%) and 120 (52.2%), (p < 0.001). Mean reader confidence was 90.1 for 150 HU, 79.9 for 130 HU, and 74.0 for 120 HU (p < 0.001). ConclusionBetween the 150, 130, and 120 HU thresholds, 150 HU performed best overall for making the diagnosis of gout on DECT. Further research is needed to determine if there is utility for utilizing lower threshold settings for certain clinical scenarios.

ОЧИСТКА ВОДОЭМУЛЬСИОННОЙ ФАЗЫ ПРИ САНАЦИИ УГЛЕВОДОРОДНЫХ ЗАЛЕЖЕЙ С ИСПОЛЬЗОВАНИЕМ ЗАВОДСКИХ СТАНЦИЙ АЭРАЦИИ

The long-term activity of oil refineries has led to the formation of man-made hydrocarbon deposits under their sites. The deposit is a lenticular formation, elongated in plan for several kilometers towards the groundwater discharge zone, penetrating into the geo-environment up to the first aquifer. The reserves of technogenic deposits can be commensurate with traditional natural deposits. On the one hand, technogenic deposits are a formation containing a mixture of raw materials and processed products of various fractions and commercial quality hydrocarbons. In this case, the content is extracted from the rocks with the help of pumping equipment of a network of production wells, separated from the water component and transferred for use or processing as a secondary material resource. On the other hand, a field containing sub-grade hydrocarbons is a significant water-oil emulsion. It is a constant source of negative impact on the environment and pollution of adjacent fragments of the geological environment. The use of a water-based layer containing hydrocarbons in concentrations insufficient for resource use is its treatment as contaminated wastewater. Purification of the water-emulsion phase from residual hydrocarbons is lengthy and extremely costly and requires new modular treatment facilities at the location of the hydrocarbon deposit or reserve capacities at existing plants.

Impact‐Generated Permeability and Hydrothermal Circulation at the Vredefort Impact Structure, South Africa

AbstractThe 2.02 billion year old Vredefort impact structure in South Africa offers a unique opportunity to study large‐scale impact processes on Earth. Vredefort's large size (∼250 km in diameter) and eroded topography provides the opportunity to study the effects of shock physics at depth and post‐formation hydrothermal alteration. In this work, we simulate the formation of the Vredefort structure building upon recent shock physics (iSALE) simulations. We expand those simulations to cover a wider range of input conditions, and compute impact‐driven porosity and permeability. The latter quantities are used to perform fluid mobility simulations (HYDROTHERM). We find that the Vredefort event produced significant impact‐generated porosity (up to 30%) in an annulus from about 50 to 100 km from the center and up to several kilometers in depth. The corresponding estimated permeability (up to 10−12 m2) would have allowed for large scale subsurface fluid flows. Our hydrothermal calculations show that the Vredefort impact event could have generated a complex crustal fluid pattern within the crater rim that lasted for hundreds of thousand years, with localized flow concentration regions, opening a new interpretation for the mobilization and location of the ore deposits in the Witwatersrand basin. The combined approach utilizing impact and hydrothermal simulations constitute a powerful tool to understand geochemical processes at Vredefort, as well as to assess the ability of large impacts to drive crustal chemistry with far‐reaching consequences for the prebiotic evolution of the early Earth.