The discovery of structural elements and zones of hydrothermal alterations by using ASTER satellite data in the margins of Gadabay and Murovdag ore districts (Lesser Caucasus, Azerbaijan)

The article considers the discovery of structural elements, zones of hydrothermal alterations and mineralization in the margins of Gadabay and Murovdag regions and the study of prospective areas for mineralization characterized by them by using ASTER satellite data. The main purpose of the research is the definition of the lithological composition of rocks, ring and linear structures and zones of hydrothermal alterations with the help of remote-sensing methods and by better technological development of special radiometric data. In order to detect the lithological composition of associated rocks of alteration zone of endogenous ores, 14 channel data of ASTER has been used. By using stereoscopic images obtained from ASTER data, it was determined that hydrothermal alterations are mainly represented by alunitization, kaolinization, sericitization, silication, pyropilitization and silification in the studied ore regions. These changes were shown to be characteristic for copper-porphyry, gold- copper pyrite, copper-polymetal and gold-copper-porphyry deposits. Strip ratios, principal component analysis (PCA), minimum of noise fraction (MNF) and selection method for least squares (LS) have been used to map hydrothermal alteration zones. The ring structures detected in the area, different fault fractures and lineaments are assessed as favourable geological structural factors for alteration and mineralization. The results obtained by ASTER image analysis confirm the presence of derivative minerals which are considered to be the product of hydrothermal alterations which are densely concentrated (kalium spathization, kaolinization, serictization, pyrophyllitization, alunitization) has been confirmed. The points each with private coordinates have been determined (defined) within separate areas with the help of remote data and relevant anomalous maps prepared. These points are considered favourable geological condition in terms of the type and intensity of hydrothermal alterations in the area. Such areas are considered a sign of indirect search significant for the detection of copper-polymetallic, copper-porphyry, copper-pyrite and gold-pyrite type of mineralization with epithermal origin in the region.

Ore-magmatic systems of the copper-porphyry type of the Greater Caucasus

Статья посвящена выявлению особенностей геологического строения и минерагении Танадон-Сангутидон-Казбекского района проявлений медно-порфировых минерализаций Центральной части Большого Кавказа и оценке соответствия геологических обстановок оруденения современным моделям рудно-магматических систем медно-порфирового типа. Актуальность работы определяется необходимостью разработки научно-методической основы прогнозирования и поисков скрытого оруденения. Цель исследования.Выявить особенности геологии и минерагении Танадон-Сангутидон-Казбекского рудного района и установить соответствие обстановок оруденения современным моделям рудно-магматических систем медно-порфирового типа. Методы. Сравнительно-геологический и металлогенический анализ на основе современных геоинформационных технологий в среде программного комплекса ArcGIS. Результаты. Установлено, что рудно-магматические системы исследуемого района соответствуют геолого-структурной позиции медно-порфировых месторождений. Изученный район объединяет группу медно-порфировых рудно-магматических систем, связанных с малыми гранитоидными интрузиями теплинского плиоцен-плейстоценового комплекса. Здесь также отмечаются рудопроявления вольфрама, мышьяка, золота, сурьмы и др., составляющие единый генетический ряд, в котором медно-порфировое оруденение занимает вполне определенную позицию, – приурочено к порфировой фазе новейшего интрузивного магматизма. Сопоставление обстановок проявления позднекайнозойского оруденения и его характеристик в пределах изученных рудоносных площадей с основными элементами типовой модели медно-порфировой системы позволяет рассматривать Сангутидонский, Теплинский и Танадонский рудные узлы как выражение надстраивающих друг друга по вертикали частей единой рудно-магматической системы медно-порфирового ти­па. Продук­тивная на медно-порфировое оруденение новейшая гранит-гранодиоритовая формация Большого Кавка­за образовалась в условиях повторноорогенного режима активизации региона и наложена на его гетерогенный субстрат. Последний в пределах изучаемого района характеризуется двухэтажным стро­ением и состоит из нижне-среднеюрского вулканогенно-осадочного комплекса чехла и доюрского основания, в котором главную роль иг­рают докембрий – нижне-среднепалеозойские метаморфические тол­щи кристаллического фундамента Большого Кавказа, прорванные пале­озойскими гранитоидами Главного хребта. Состав поздненеогеновых гранитоидов находится в зависимости от состава субстрата, как на глубинных уровнях его анатектического плавления, так и на путях подъема образованных при этом магм. В этой связи повышенная основность гранитоидов полифазного теплинского комплекса, сформированных в гипабиссальных и субвулканических условиях, обусловлена более высокой по сравнению с соседними блоками степенью мафичности субстрата исследуемого района, включающего ряд базальтоидных или близких к ним по составу толщ The article is devoted to the identification of the features of the geological structure and mineralogy of the Tanadon-Sangutidon-Kazbek district of the manifestations of copper-porphyry mineralization in the Central part of the Greater Caucasus and the assessment of the correspondence of the geological conditions of mineralization to modern models of ore-magmatic systems of the copper-porphyry type. The relevanceis determined by the need to develop a scientific and methodological basis for forecasting and searching for hidden mineralization. Aim. To identify the features of the geology and mineralogy of the Tanadon-Sangutidon-Kazbek ore region and to establish the correspondence of the mineralization conditions to modern models of ore-magmatic systems of the copper-porphyry type. Methods.Comparative geological and metallogenic analysis based on modern geoinformation technologies in the environment of the ArcGIS software package. Results. It is established that the ore-magmatic systems of the studied area correspond to the geological and structural position of copper-porphyry deposits. The studied area unites a group of copper-porphyry ore-magmatic systems associated with small granitoid intrusions of the Teplinsky Pliocene-Pleistocene complex. There are also ore occurrences of tungsten, arsenic, gold, antimony, etc., which make up a single genetic series, in which copper-porphyry mineralization occupies a well - defined position-it is timed to the porphyry phase of the latest intrusive magmatism. The comparison of the conditions of the Late Cenozoic mineralization and its characteristics within the studied ore-bearing areas with the main elements of the typical model of the copper-porphyry system allows us to consider the Sangutidon, Teplinsky and Tanadon ore nodes as an expression of the parts of a single ore-magmatic system of the copper-porphyry type superstructuring each other vertically. The newest granite-granodiorite formation of the Greater Caucasus, which is productive for copper-porphyry mineralization, was formed under the conditions of a repeated-rhogenic regime of activation of the region and superimposed on its heterogeneous substrate. The latter within the studied area is characterized by a two-story structure and consists of the Lower-Middle Jurassic volcanogenic-sedimentary complex of the cover and the Pre - Jurassic base, in which the main role is played by the Precambrian-Lower-Middle Paleozoic metamorphic strata of the crystalline basement of the Greater Caucasus, broken by Paleozoic granitoids of the Main Ridge. The composition of Late Neogene granitoids depends on the composition of the substrate, both at the deep levels of its anatectic melting, and on the ascent paths of the magmas formed during this process. In this regard, the increased basicity of granitoids of the polyphase Teplinsky complex formed under hypabyssal and subvolcanic conditions is due to a higher degree of maficity of the substrate of the studied area, which includes a number of basaltoid or similar strata in composition, compared to neighboring blocks.

Integration of Dual Border Effects in Resource Estimation: A Cokriging Practice on a Copper Porphyry Deposit

Hierarchical or cascade resource estimation is a very common practice when building a geological block model in metalliferous deposits. One option for this is to model the geological domains by indicator kriging and then to estimate (by kriging) the grade of interest within the built geodomains. There are three problems regarding this. The first is that sometimes the molded geological domains are spotty and fragmented and, thus, far from the geological interpretation. The second is that the resulting estimated grades highly suffer from a smoothing effect. The third is related to the border effect of the continuous variable across the boundary of geological domains. The latter means that the final block model of the grade shows a very abrupt transition when crossing the border of two adjacent geological domains. This characteristic of the border effect may not be always true, and it is plausible that some of the variables show smooth or soft boundaries. The case is even more complicated when there is a mixture of hard and soft boundaries. A solution is provided in this paper to employ a cokriging paradigm for jointly modeling grade and geological domains. The results of modeling the copper in an Iranian copper porphyry deposit through the proposed approach illustrates that the method is not only capable of handling the mixture of hard and soft boundaries, but it also produces models that are less influenced by the smoothing effect. These results are compared to an independent kriging, where each variable is modeled separately, irrespective of the influence of geological domains.

Assessing physical and mechanical properties of enclosing rock in the course of Malmyzhskoe gold-copper-porphyry deposit development

Introduction. This work presents the results of complex technological and mineralogical studies. It has been discovered that some natural rocks are characterized by physical and mechanical properties variability 58 "Izvestiya vysshikh uchebnykh zavedenii. Gornyi zhurnal". No. 3. 2021 ISSN 0536-1028 even within a local area. It must be taken into account when assessing enclosing rocks utilization options. The results of Malmyzhskoye rock physical and mechanical properties study at the stage of geological exploration are considered. Research aim is to carry out integrated technological and mineralogical research and laboratory tests on rock physical and mechanical properties to assess the feasibility of using hard enclosing rock for construction. Research methodology. The geological and structural features of the field were established by comparative analysis of geological sections and maps, structural documentation of the core. In laboratory conditions, the physical and mechanical properties of the host rocks that make up the gold-copper-porphyry deposit were established. Results. After studying the mineral (chemical) composition and physical and mechanical properties of rocks, it was possible to obtain the dependence of the strength index on the structure, as well as on the content of dark-colored minerals and plagioclases. At the same time, there are no significant correlations between strength and density within the same rock type. Conclusions. The analysis shows that rocks with the same mineral composition and equal values of the true density, but with different texture and structure, show differences in strength properties. Keywords: Malmyzhskoe deposit; breakability; physical and mechanical properties; rocks; petrographic analysis; density; strength.

Geological position of the gold-sulfide-quartz deposits of the Chilean active margin

Research subject. The gold-sulphide-quartz deposits of Central Chile are typical prospecting objects, having small ore intervals (from the first tens of centimetres to 1 m), intermittent and nested ore distribution and extremely uneven gold contents.Materials and methods. The patterns of ore mineralization distribution are considered against the background of the results of modern geophysical studies of the lithosphere: the Moho surface, density and thermal regime of the upper mantle. Detailed studies were conducted on the Yapin ore field.Results. It was shown that the faults controlling gold-sulphidequartz mineralization are derivatives of shear tectonics under the conditions of a transpression regime along the Chilean active margin. At an early stage, these faults developed in a right-shift environment, which was accompanied by the introduction of diabase dikes into the northeastern faults, and gold-sulfide-quartz mineralization superimposed on the dikes was deposited during the left-shift stage. The geological structure of the deposits in the ore field Yapin was characterized. It was shown that a diverse mineralization is developed in the ore field - copper-porphyry, IOCG-type and gold-sulphide-quartz. According to geochemical data, the latter is characterized by a clear enrichment of chalcophilic elements (Au, As, Ag, Cd, Cu, Bi, Pb, Zn, Te, Co). The marked enrichment of Bi, Te and Co ores indicates the participation of magmatic fluid in ore formation and the similarity of the mineralization of the Escondida deposit with the type of gold deposits associated with granitoid intrusions. According to geochemical features, gold-sulphide-quartz mineralization in the general zoning pattern occupies a boundary position between IOCG-type objects and copper-porphyry deposits.Conclusions. The conclusion is drawn about the independence of gold-sulphide-quartz mineralization and its difference from epithermal gold deposits. It is noted that, in the volcanic belts of the North-East of Russia, the prospects for discovering unconventional gold-sulphidequartz deposits similar to those of Central Chile are rather real.

Engineering and geological zoning of the Malmyzhsky deposit weathering crusts (Svoboda area)

Introduction. Interest in the study of weathering crusts arose at a time when geological engineers faced the problem of developing open pits formed by eluvial soils. However, the exact and detailed division of the weathering crusts into engineering-geological zones, especially when studying mineral deposits, is not given due attention even today. Therefore, in the course of prospecting, it is important to correctly determine weathering crust type and profile, and establish the possibility of changing the engineering and geological conditions when opening the rock mass by mine workings for further slope stability prediction of the designed mining structures. Research aim is to determine vertical engineering-geological zoning of the Malmyzhsky deposit weathering crusts (Svoboda area) and identify patterns in alluvial deposits physical and mechanical properties change, which define the safety of mine development. Methodology. A significant number of Russian and foreign scientists have considered the formation of weathering crusts from different positions. They established the geochemical zoning and engineeringgeological zoning of the weathering crusts. Results. The article describes the Svoboda area at the Malmyzhsky gold-copper-porphyry deposit. Engineering and geological zoning of the weathering crust section was carried out according to a set of features, including structural and textural features, mineral composition, physical and mechanical properties of rocks. Within it, three zones are identified at the Malmyzhsky field, the Svoboda area: IV – dispersed, III – litomarge, and II – clastic. Physical and mechanical properties of rock building up the considered weathering crust have been analyzed proving that change in geological conditions within even one zone of the Malmyzhsky gold-copper-porphyry deposit (Svoboda area) entails a change in the choice of projected pit wall angles.