The article is devoted to the implementation of the methodology for paleovolcanic structure analyzing using 3D visualization of the model of the geological territory structure based on the relief digital model. The approach used made it possible to identify two paleovolcanic apparatuses and their structural elements: cone fragments, explosive domes, porphyritic stocks, ring fault zones with localization of dike belts in them. This, within the framework of the evolution model of porphyry ore systems, made it possible to identify promising areas for prospecting on ore objects of a given type. The procedure was checked on the basis of geochemical survey results. The regular control by the selected structural elements of geochemical fields was shown. The analysis of the spatial position of the selected structural blocks with a certain geochemical characteristic rather well into the evolution model of the porphyry ore systems. In all cases the control of geochemical halos by porphyry stocks is noted, the material rock complexes that are fragments of the zonal stone hat of the porphyry ore object, are quite clearly distinguished. Within the area of work, three ore-magmatic systems can be identified at a low level of erosion shear, potentially accompanied by porphyry-type ore mineralization.

Среднее по запасам золота месторождение Угахан, расположенное в пределах крупнейшей в России Ленской золоторудной провинции, принадлежит к группе месторождений «сухоложского» генетического типа. Представлены результаты петрографического, минералогического и изотопно-геохимического изучения золоторудной минерализации месторождения. Разработана схема последовательности минералообразования на месторождении, которая включает пять стадий: 1) в течение ранней (синдиагенетической) стадии происходило образование фрамбоидного пирита-1, обогащенного Au, Ni, Co, As; 2) на стадии катагенетического преобразования рудоносных осадков происходила перекристаллизация раннего пирита-1 и кристаллизация пирита-2, также обладающего повышенными содержаниями Au, Ni, Co, As; 3) формирование в рудах пирротина происходило на стадии прогрессивного метаморфизма из водно-углекислого флюида с повышенным содержанием H2S; 4) собственно рудная стадия, представленная на месторождении минеральной ассоциацией пирит-3, галенит, сфалерит, халькопирит, самородное золото, коррелирует с развитием в регионе регрессивного метаморфизма; 5) кристаллизация пострудного идиоморфного крупного пирита-4. Комплекс геохимических и изотопных (δ34S и Pb-Pb) данных позволяет исключить привнос минералообразующих компонентов при гидротермально-метасоматическом преобразовании рудовмещающих пород из дополнительного (внешнего) источника. Значения δ34S, варьирующие для ранних морфотипов пирита в рудах месторождения в относительно узких диапазонах от +5.7 до +9.1 ‰, близки к величинам δ34S (+4.2… +16.4 ‰) безрудных пород бужуихтинской свиты. Pb-Pb изотопные характеристики, а также установленные закономерности в вариациях изотопного состава Pb для золоторудной минерализации указывают на преимущественное поступление элемента из неопротерозойских метаосадочных толщ. Минералогические и геохимические особенности месторождения Угахан согласуются с представлениями о метаморфогенном происхождении золоторудных месторождений «сухоложского» типа, что подтверждает перспективность пород бужуихтинской свиты на обнаружение новых золоторудных объектов в регионе. The Ugakhan gold ore deposit is located within the Lena gold ore province, the largest one in Russia. It belongs to the group of deposits of the Sukhoi Log genetic type. We present results of petrological, mineralogical, and isotope-geochemical study of gold mineralization at the deposit. A scheme of the sequence of mineral formation at the deposit has been developed, which includes five stages: (1) the early (syndiagenetic) stage, when framboid pyrite I enriched in Au, Ni, Co, and As formed; 2) the stage of catagenesis of ore-bearing sediments, with recrystallization of early pyrite I and crystallization of pyrite II, also with elevated Au, Ni, Co, and As contents; (3) the stage of progressive metamorphism, with the formation of ore pyrrhotite from a water–CO2 fluid with a high content of H2S; (4) the ore formation stage, marked by an assemblage of pyrite III, galena, sphalerite, chalcopyrite, and native gold at the deposit, which was synchronous with regressive metamorphism in the region; (5) crystallization of post-ore euhedral coarse-grained pyrite IV. The geochemical and isotope (δ34S and Pb–Pb) data rule out the input of mineral-forming components from an additional (external) source during the hydrothermal-metasomatic transformation of ore-bearing rocks. The δ34S values in the early morphotypes of pyrite in the deposit ores vary from +5.7 to +9.1‰ and are close to the δ34S values of the barren rocks of the Buzhuikhta Formation (+4.2 to +16.4‰). The Pb–Pb isotope characteristics and regularities of variations in Pb isotope composition established for gold mineralization indicate a predominant inflow of lead from Neoproterozoic metasedimentary strata. The mineral and geochemical specifics of the Ugakhan deposit are consistent with the concept of the metamorphic origin of gold deposits of the Sukhoi Log type, which confirms that the rocks of the Buzhuikhta Formation are promising for new gold ore objects.

Ugakhan gold ore deposit is located within the Lena gold ore province, the largest one in Russia. It belongs to the group of deposits of the Sukhoi Log genetic type. We present results of petrological, mineralogical, and isotope-geochemical study of gold mineralization at the deposit. A scheme of the sequence of mineral formation at the deposit has been developed, which includes five stages: (1) the early (syndiagenetic) stage, when framboid pyrite I enriched in Au, Ni, Co, and As formed; 2) the stage of catagenesis of ore -bearing sediments, with recrystallization of early pyrite I and crystallization of pyrite II, also with elevated Au, Ni, Co, and As contents; (3) the stage of progressive metamorphism, with the formation of ore pyrrhotite from a water-CO2 fluid with a high content of H2S; (4) the ore formation stage, marked by an assemblage of pyrite III, galena, sphalerite, chalcopyrite, and native gold at the deposit, which was synchronous with regressive metamorphism in the region; (5) crystallization of post -ore euhedral coarse -grained pyrite IV. The geochemical and isotope (delta 34S and Pb-Pb) data rule out the input of mineral -forming components from an additional (external) source during the hydrothermal-metasomatic transformation of ore -bearing rocks. The delta 34S values in the early morphotypes of pyrite in the deposit ores vary from +5.7 to +9.1%o and are close to the delta 34S values of the barren rocks of the Buzhuikhta Formation (+4.2 to +16.4%o). The Pb-Pb isotope characteristics and regularities of variations in Pb isotope composition established for gold mineralization indicate a predominant inflow of lead from Neoproterozoic metasedimentary strata. The mineral and geochemical specifics of the Ugakhan deposit are consistent with the concept of the metamorphic origin of gold deposits of the Sukhoi Log type, which confirms that the rocks of the Buzhuikhta Formation are promising for new gold ore objects.

In addition to the widely known large-volume Sukhoi Log–type gold deposits (e.g., Sukhoi Log, Verninskoe, etc.), the Lena gold province also hosts a series of objects that differ significantly in thte stratigraphic, mineralogical–petrographic, isotopic, and geochemical characteristics, as well as reserves. The Ozherel’e deposit is one of the most famous among these objects. This paper presents the main characteristics including similar and distinct features with Sukhoi Log–type deposits. The results of mineralogical–petrographic and isotopic studies provide no reason to ascribe the Ozherel’e deposit to the Sukhoi Log genetic type.

The results of studying the isotopic, geochemical, and TEDS properties of various generations of pyrite and pyrrhotite from the Ugakhan deposit, Bodaibo district of Irkutsk region, are presented. Differences in the composition of impurities are established. Early pyrites (py-I and py-II) are characterized by the presence of Ni, Co, Cr, and Au admixtures, the electronic type of conductivity, and values of δ34S ~ +5.6‰; py-III is characterized by a decreased amount of Ni, Co, and Cr, and an increased amount of As, the hole type of conductivity, and δ34S from +8.6 to +9.1‰. Post-ore py-IV and py-IVQ are characterized by the smallest admixture concentrations, the electronic type of conductivity, and isotopically lighter sulfur (δ34S ≤ +3.8‰).

This paper provides new data on various pyrite and pyrrhotite generations at the Golets Vysochaishy gold deposit, Bodaibo district, Irkutsk Oblast. These generations are distinguished by morphological, geochemical, and isotope (δ 34 S) features. The established features of pyrite generations reflect the evolution of the Golets Vysochaishy deposit. Each pyrite generation is associated with a certain evolutionary stage of Neoproterozoic rocks in the region: (1) diagenesis (610 Ma), (2) catagenesis (570–520 Ma), (3) metamorphism (~450–430 Ma), and (4) tectono-magmatic activation (330–270 Ma). The 40 Ar/ 39 Ar ages of the third and fourth pyrite generations correspond to those of previously determined gold mineralization and granite magmatism.

The paper presents the results of the detailed structural analysis and 40Ar/39Ar dating of the deformations in the Golets Vysochaishii deposit area. The geological and structural studies showed the folded-deformation sequence from large lying folds through axial-plane cleavage formation and cleavage to quartz-filled fractures. The 40Ar/39Ar dating of syntectonic sericite yielded the ages of two Hercynian tectonic impulses – 340 and 320 Ma. This stage is characterized by the earlier-known successive complication of the Early Paleozoic fold-nappe structure of the area. Analysis has been made on four samples taken from different sites and characterized by different sets of deformational structures. The 40Ar/39Ar age of 340 Ma reflects the formation of small-size folds as a result of interlayer sliding and sliding along the cleavage axial planes. The 40Ar/39Ar age of 320 Ma reflects the formation of discretely manifested crenulation cleavage and low-Au, low-sulfidation quartz veins oriented obliquely to the elements of bedding and axial-plane cleavage.

The paper presents the results of the detailed structural analysis and 40Ar/39Ar dating of the deformations in the Golets Vysochaishii deposit area. The geological and structural studies showed the folded-deformation sequence from large lying folds through axial-plane cleavage formation and cleavage to quartz-filled fractures. The 40Ar/39Ar dating of syntectonic sericite yielded the ages of two Hercynian tectonic impulses – 340 and 320 Ma. This stage is characterized by the earlier-known successive complication of the Early Paleozoic fold-nappe structure of the area. Analysis has been made on four samples taken from different sites and characterized by different sets of deformational structures. The 40Ar/39Ar age of 340 Ma reflects the formation of small-size folds as a result of interlayer sliding and sliding along the cleavage axial planes. The 40Ar/39Ar age of 320 Ma reflects the formation of discretely manifested crenulation cleavage and low-Au, low-sulfidation quartz veins oriented obliquely to the elements of bedding and axial-plane cleavage.

It is now known that coals throughout the world contain many valuable elements. In the Irkutsk Region, coal mining is provided by the resources of the Irkutsk coal-bearing basin. The Irkutsk basin is a large area of the Jurassic continental sedimentary deposits in the south of the Siberian craton, with the Cheremkhovo, Prisayan and Kuda formations. The upper Cheremkhovo formation is the primary coal-bearing formation of the Irkutsk basin. This paper presents the geochemical data on the Karataevsky coal mine. Trace element concentrations were obtained using X-ray fluorescence spectrometry. The average Th content (14.24 ppm) in the studied coal seam is higher than that in most of the world coals. The Co (35 ppm), F (1008 ppm), Sn (12 ppm), Th (34 ppm) concentrations in the coal shale consisting primarily of kaolinite (90 %) are higher than in ordinary coals. The coals should be used considering the concentrations of potentially hazardous elements that are high relative to the world coals. The studied coals can be interesting in terms of their slight enrichment in Y, with an average concentration of 19.7 ppm, which is 2.4 times higher than that in the world coal.

Summary The results of studies of rocks and ores of the Krasny deposit located on the territory of the Baikal-Patomsky upland (north of the Irkutsk region, Russia) are presented. According to the study data, the ore mineralization of the deposit was formed in the conditions of the green-shale facies of metamorphism (200–400° C). The following sequence of mineral formation is recorded: Early framboidal and micrograin pyrite (I and II), with nanoparticles of native gold evenly distributed over the surface, is superimposed with a high-temperature association of ore minerals, including arsenopyrite, pyrrhotite, pyrite-III, native gold, galena, sphalerite, and faded ores, associated with the development of regional metamorphism of the green shale facies. At the post-ore stage, pyrite-IV crystallizes in the quartz-carbonate rim.

Summary A typical lithogeochemical survey with bulk analysis of samples is an important component of a complex of prospecting works in open areas, especially in dissected mountain areas with widespread development of thin eluvial-deluvial sediments. typical LGH often leads to the omission of ore objects in semi-closed and especially closed areas. Now, there are a number of methods of geochemical surveying, based not on the hypergene destruction of ore bodies that have emerged on the day surface, but on the diffusion of salt and gas components, including metal vapors, filtration and electrochemical transfer processes. This work presents a comparative evaluation of two geochemical methods MMI and a typical LGH, carried out in the area of ​​Eastern Transbaikalia, characterized by complex landscape-geochemical conditions. As a result of comparing the two methods, we can say that the MMI method confidently identifies secondary scattering halos of Au, Ag, Cu and other indicator elements of the ore association. The intensity of the anomalies localized by the MMI method significantly exceeds the intensity of the anomalies of the elements of the ore association, localized according to the results of a typical lithogeochemical survey. All this makes it possible to judge the higher search efficiency of the MMI method in unfavorable landscape and climatic conditions.