The Natalkinskoe Gold Deposit: Formation Conditions Based on Paragenetic Analysis of Dike and Ore Vein Networks

<p>Subduction zones are principal pathways for the cycling of volatiles such as <sub> </sub>hydrogen and carbon<sub></sub>from the Earth’s surface to the mantle and back to the atmosphere. This cycling has significant long-term effects on Earth’s climate. However, the processes that lead to volatile release during subduction and total volatile fluxes are poorly understood. In our study, we will quantify and characterize the network architecture of dehydration pathways exhibited as mineralized olivine-bearing metamorphic veins in the exhumed meta-serpentinites from the Erro-Tobbio unit, Italy [1]. Applying network analytical methods and graph theory both macroscopically and microscopically can provide the mode of propagation and describe the controlling factors affecting the evolution of these dehydration networks. Furthermore, multiscale observations can confirm the scalability of the vein network and if quantitative results such as permeability or volatile flux can be extrapolated to larger scales.</p><p>Along with 2-D network analysis, these vein networks will be analyzed in 3-dimensions using X-ray tomography and sophisticated machine-learning methods, such as generative adversarial networks. The results of both will be compared, which can then assure whether current machine-learning methods can effectively create statistically equivalent copies of these networks. Lastly, the synthesis of 2-D and 3-D multiscale results should provide meaningful parameters for accurate calculations of volatile flux during the dehydration of subducting slabs. </p><p> </p><p>[1] Plümper <em>et al.</em> (2017) <em>Nature Geoscience </em><strong>10(2)</strong>, 150-156.</p>

The Curiosity rover's campaign in the Gale crater on Mars provides a large set of close-up images of sedimentary formations outcrops displaying a variety of diagenetic features such as light-toned veins, nodules and raised ridges. Through 2D and 3D analyses of Mastcam images we herein reconstruct the vein network of a sample area and estimated the stress field. Assessment of the spatial distribution of light-toned veins shows that the basin infillings, after burial and consolidation, experienced a sub-vertical compression and lateral extension coupled with fluid overpressure and cracking. Overall, rock failure and light-toned veins formations could have been generated by an overload produced by infilling material within the basin.

Gold occurs in a wide range of deposit types and settings. In the last decade, significant progress has been made in the definition, classification, characterization, thereby aiding understanding of the main gold deposit types. The present work aims to provide an update on the current state of knowledge on the different types of gold deposits models, geodynamics, their mode of formation and the condition suitable for their formation Several subsets of gold deposits are distinguished from one another on the bases of and their main geological models and their mode of formation described. Gold deposits of magmatic-hydrothermal origin are classified into Porphyry, Epithermal, Skarn, Iron Oxide-Copper-Gold and Intrusion related deposits; those of hydrothermal origin are Orogenic, Volcanogenic Massive Sulphide deposits, and Carlin-type; while those of Sedimentary Origin are placers. In terms of the major Period of gold deposit formation, the Mesoarchean was the largest gold period. Other gold peaks followed, particularly in the Neoarchean, Paleoproterozoic and Paleozoic while numerous and diverse gold deposit types were formed during the Cenozoic era.Wide varieties of geodynamic contexts in which each of the gold deposits are formed being explained while the conditions favourable for its formation are also being summarized. With the recent rise in the price of gold, mining companies and research centers continue to provide lighting of the key geology features of then ore-forming environments and the key geologic manifestations of the different deposit types.

The article covers a number of issues related to the problem of the specialist-professional formation in the system of higher education of Ukraine, taking into account global challenges and prospects for the development of the world economy, national economies and modern society. In the process of scientific research, an understanding of the basic concepts of «profession», «vocational training», «formation of a specialist-professional», «IHE activity» has been formed. The role and significance of higher education in professional training of specialists, competitive in the labour market are revealed; the priority directions of development of the industry are singled out in accordance with the state educational policy requirements and the Bologna process tasks in the conditions of the European Higher Education Area formation and the integration implementation. The article pays particular attention to analysing the models of national strategies for the higher education development and selecting the model of the Ukrainian universities development strategy on the path to their promotion to world rankings, referring to the experience of autonomy, mission, results of activity and achievements of European and world universities. Consequently the research analyses of the educational institutions network during the years of Ukraine's independence, taking into account external destabilizing factors; gives the characteristic of the local IHEs’ activity, including universities, during the period of reforming and modernizing the higher education system according to European standards and time requirements; determines the new approaches and directions of the IHE's activity improvement in the field of training qualified specialists for the industrial and social spheres. Moreover the article reveals the features of key trends for the modern education sphere, among them there is a globalization, the factor of ICT, the growth of non-system education, individualization and personalization of educational trajectories. It also gives the characteristic features of a competitive specialist-professional who is able to function effectively in the modern labour market. The benefits of this study are: the defined forms of the educational process organization at IHE in accordance with the Law of Ukraine «On Higher Education»; the given classification of innovative teaching methods for realizing of the educational process participants’ abilities and talents, basing on the study of scientific and methodological literature; the determined new approaches and directions of the IHE's activity improvement in relation to the training of qualified specialists for the industrial and social spheres. On this basis, the training of competent specialist-professionals should be considered as one of the priority areas of scientific research with the definition of long-term educational strategies, including goals, tasks, scientific approaches, positions, directions and ways of their implementation in the higher education system. In the search process, the methods of theoretical research and practical implementation of this problem are used, in particular: analysis and generalization of scientific approaches and ways for improving the professionals formation process in the higher education system; international experience synthesis and comparison, normative legal acts and peculiarities of the IHE work in the professional staff training; induction and deduction when disclosing forms and methods of future specialists’ educational activity, gaining their professional qualities and characteristics.

Formulation of the problem. The State Hydrogeological Monitoring Network has to provide the necessary information to manage groundwater resources and prevent negative changes in the geological environment. Currently, there is a negative tendency to decrease the number of observation wells, loss of information about the space-time variability of the hydrogeological regime elements in Ukraine. In conditions of limited funding, an important task is to develop an effective strategy for reforming the hydrogeological monitoring system, taking into account international experience and based on modern geoinformation technologies. Particular attention has to be given to transboundary territories. One of them is the Pripyat River basin, which is characterized by the low level of the State Hydrogeological Monitoring Network representativeness, both in comparison with European Union standards and with the existing groundwater monitoring network of neighbouring Belarus. The purpose of the article is to evaluate the actual state of the hydrogeological observation wells network and optimize it within the territory of the Ukrainian part of the transboundary Pripyat watershed basin. Methodology and materials. The State Scientific and Production Enterprise "Geoinform of Ukraine" database of State Groundwater Monitoring System composition and functioning as well as zoning map under the conditions of water exchange formation in the upper water-bearing level were used for the study. For the studied territory of the water exchange basin of Pripyat, the analysis of density and uniformity of the observation points distribution as well as the variogram analysis of the spatial distribution of groundwater-level altitudes within the study area were carried. For the actual monitoring network, the expected error of the spatial modelling of the groundwater-surface was evaluated. Results. The obtained results of the geostatistical analysis made it possible to substantiate the project wells locations within the water exchange sub-basins to improve the quality of hydrogeological monitoring problem solutions. Scientific novelty. The method of the hydrogeological monitoring network optimization has been improved based on geoinformation and geostatistical approaches and implemented for the Ukrainian part of the Pripyat River basin, taking into account the hydrogeological conditions of the territory and the configuration of the existing network. Practical significance. Optimization and increment of the observation wells network, taking into account the obtained results, will provide the effective functioning of the hydrogeological monitoring system within the Ukrainian part of the Pripyat River basin and will have an economic effect, given that the cost of any measures to improve the groundwater quality and quantity is far more expensive than the monitoring system optimization.

Structure factors of the formation of a new dense phase on dislocation boundaries in Mg2Si-based alloys

Geology and fluid characteristics of the Ulu Sokor gold deposit, Kelantan, Malaysia: Implications for ore genesis and classification of the deposit

Resource estimation on gold (Au) deposits usually requires costly Au assays and is often characterized by high degree of uncertainty especially in areas with limited number of samples. This paper reports a refinement of a novel machine learning approach (GS-Pred) that incorporates network analysis for geology-based anomalous data detection and outlier removal, and adopts feature weighting using a spatial self-similarity model inspired by kriging to enhance prediction performance for in situ Au-grade estimation. In this application, machine learning algorithms are integrated with sequential-kriging block modeling for high resolution in situ grade estimation. This process is fully automatable, and it utilizes both geological data and Au assays, making it possible to also estimate Au grade in areas that only have geological descriptions. The results of our expanded GS-Pred and block modeling, using data from the auriferous conglomerates of the Witwatersrand Basin (South Africa), demonstrate improvements in the GS-Pred performance and flexibility relative to the original algorithms. Additionally, our results provide further evidence of strong sedimentological control on Au concentration within the Witwatersrand Basin, which is suitable for quantitative predictions. Our algorithms feature fast data processing, geology- and assay-based outlier detection, visualization of complex geospatial data, and they open new avenues for intelligent and automated in situ Au-grade prediction. We demonstrate that GS-Pred target predictions are feasible substitutes for assays for the purpose of block modeling under suitable deployment conditions.

The Bjorkdal gold deposit is located in the eastern part of the Early Proterozoic Skellefte district in northern Sweden. The ore zone is hosted by a granitoid which intrudes a 1.9 Ga old supracrustal sequence and consists of a network of quartz veins between two shear zones. The ore mineralogy, alteration assemblages, ore fluid characteristics and general setting of the Bjorkdal deposit reveal many similarities with mesothermal Archean systems. Three types of fluids are represented by fluid inclusions observed in quartz, scheelite and calcite. The first type consists of a CO2-rich fluid which is syngenetic with the formation of the quartz veins. These inclusions occur in quartz and scheelite. Isotopic equilibrium temperatures derived from quartz-scheelite pairs reflect depositional temperatures around 375 °C. Molar volumes of the carbonic fluid inclusions, ranging down to 55 cm3mole, indicate a maximum lithostatic trapping pressure of 1.8 kbar. These fluids were generated at depth in conjunction with early orogenic magma-forming processes. The gold was introduced to the vein system by the carbonic fluid but the gold was deposited after reactions between this fluid and the wall-rock, producing a slightly alkaline, more CH4-rich aqueous type 2 fluid. Fluid inclusions of this chemically modified fluid indicate that the precipitation of the gold, together with pyrrhotite, pyrite and chalcopyrite, occurred under heterogenous conditions at a temperature of 220 °C and a hydrostatic pressure of 0.5 kbar. The gold deposition occurred from fluids with a δ18O signature of around +8‰ and δD values close to zero per mil. Any metamorphic influence on the stable isotopic signatures is regarded as minimal. The isotope data suggest rather that a surface-derived fluid component had access to the vein system during this process. At a post-vein forming stage (metamorphic stage ?) a secondary episode of gold mobilization occurred as suggested by the aqueous type 3 inclusions trapped in cross-cutting microfractures in quartz and randomly in calcite, and with homogenization temperatures between 145–220 °C and a salinity up to 11eq. wt.% NaCl.

Showa Shell reduces CO 2 produced in hydrogen generation

The La Bellière gold and antimony district (French Armorican Massif): A two-stage evolution model controlled by Variscan strike-slip tectonic

Tracing the magmatic/hydrothermal transition in regional low-strain zones: The role of magma dynamics in strain localization at pluton roof, implications for intrusion-related gold deposits

This paper reviews and summarizes the available information on the composition of palladian gold with various contents and sets of isomorphic impurities (Ag, Cu, Hg) at 50 deposits and ore occurrences with Au-Pd mineralization. It is revealed that Palladian gold is represented by the systems Au–Pd, Au–Pd–Hg, Au–Pd–Cu, and Au–Pd–Ag–Hg, but more frequently corresponds to Au–Pd–Ag, Au–Pd–Ag–Cu, and Au–Pd–Ag–Cu–Hg. Objects with palladian gold belong to different types of gold deposits and to the deposits at which the main components of ores are PGE, Cr, Cu, Ni, V, and Ti. We propose a classification of the types of deposits with palladian gold: (1) PGE ore deposits related to mafic–ultramafic magmatic complexes (two subtypes—(a) low-sulfide-grade (less than 2%–5% sulfides) Alaskan, and (b) high-sulfide-grade (more than 5% sulfides) Norilsk); (2) orogenic gold deposits (OG); (3) epithermal (porphyry) gold–copper deposits (EPGC); (4) iron oxide copper gold deposits (IOCG); (5) ferruginous quartzite deposits; (6) volcanic exhalation; and (7) gold-PGE placers of five subtypes corresponding to the types of 1–5 primary sources. Physicochemical conditions of the formation of palladian gold at some deposits of type 1 cover two areas—magmatic high-temperature and hydrothermal low-temperature. At the majority of deposits of types 2–4, its formation proceeds with the participation of hydrothermal fluids (300–60 °C) of various salinities (0.2–30 wt.% NaCl eq.). Palladian gold is mainly high-fineness (910‰–990‰), is less frequently medium-fineness, and contains Ag and Cu, but does not contain Hg at the deposits of types 1, 3, and 4. The only exception is the Au-Pd-Hg Itchayvayam ore occurrence (Kamchatka, Russia), for which two varieties of Pd,Hg-bearing native gold (fineness 816‰–960‰ and 580‰–660‰) are determined. Low-fineness palladian gold with the major content of Ag is typical of OGD deposits. Medium-fineness palladian gold occurs at ferruginous quartzite deposits and in volcanic exhalations. Hg, Ag, Cu-bearing high-fineness palladian gold is present mainly in placer deposits (type 7). The most common minerals in association with palladian gold are arsenides, stibioarsenides, sulfides, stannides, bismuthides, tellurides, and selenides of Pd and Pt. These are typical of deposit types 1 and 7. The minerals of Au, Ag, and Cu (tetra-auricupride, aurostibite, chalcopyrite, bornite, chalcocite, eucairite, etc.) are in association with palladian gold at OG, EPGC, and IOCG deposits. Hg minerals (cinnabar, tiemannite, coloradoite, potarite) are at some deposits (types 1, 2, 7-1, 7-4). Cu, Fe, and Pd oxides (tenorite, hematite, magnetite, PdO, (Pd,Cu)O) and Fe and Pd hydroxides (goethite, (Fe,Pd)OOH) occur at the deposits of the 3, 4, and 7 groups and indicate the highly oxidizing conditions of ore formation. The most common minerals among host minerals are quartz and muscovite, including fuchsite (Cr-Ms), chlorite, albite, K-feldspar, hornblende, and carbonates (calcite, siderite, etc.). The fineness, content, and set of impurities in palladian gold and minerals in association with it reflect the mineralogy of Au-Pd ores and allow them to be used as indicators for the deposit types.

We have studied tourmaline of the schorl – dravite – povondraite series in a sample from the Darasun porphyry-style gold deposit, Chita region, Transbaikalia, Russia. A combination of analytical procedures has been used to determine composition in terms of major elements (electron microprobe), Fe 2+ and Fe 3+ (Mossbauer spectroscopy), the probable position of Fe 3+ in the Fe-rich core of a separated grain (FTIR), the Li content (ICP–MS), and conditions of formation (fluid inclusions in coeval quartz). A significant amount of Fe 3+ has been directly determined by Mossbauer spectroscopy (83% of iron is Fe 3+ over the averaged sample). The evolution of chemical composition of the tourmalines studied here can be generalized in the following model. The first generation of low-Al and high-Fe “oxy-dravite” – povondraite (Al~3, Fe~4, Ca~0.2, □ apfu ) is followed by a second generation of higher-Al and lower-Fe “oxy-dravite” (Al~6, Fe~1.5, Ca~0.1, □~0.2 apfu ), and the third generation consists of dravite having the highest Al and the lowest Fe contents (Al > 6, Fe apfu ). Depletion of the second and third generations in Fe is caused by deposition of early sulfides. The evolution in chemical composition of the tourmalines studied here is different from that of redeposited tourmalinites in Western Carpathians, where tourmaline evolves from schorl–dravite to povondraite. The chemical composition of the Darasun tourmalines is different from Fe 3+ -rich tourmalines from evaporite formations in low K, and is similar in Mg content. At the same time, the major type of homovalent substitution (AlFe −1 ) in the tourmalines examined is similar to that in tourmalines from Sn- and Cu-porphyry deposits, and may be accepted as a prospecting guide for the porphyry-style deposits. This finding of povondraite is the third in the world and the first in hydrothermal gold deposit. The fluid inclusions in the associated quartz indicate that that first-stage tourmaline precipitated from boiling fluid at low pressure. Boiling favored the increasing oxygen activity, and resulted in the increase of Fe 3+ in that tourmaline.

Topological characterization of a polyphased gold-bearing vein network