Nickel weathering ores are used to produce metallic nickel, stainless steels, and nickel sulfate, the main component of batteries. The global production of nickel from weathering ores is increasing and has surpassed production from sulfide magmatic deposits. The efficiency of the mining and processing of nickel ores from weathering rocks is determined by their mineralogical composition. The weathering crust profile of the Kempirsay ultramafite massif is divided into three zones—leached (kerolitized) serpentinites, nontronites, and final hydrolysis minerals (later referred to as “ochers”). The kerolitized zone consists of a mixture of Ni-bearing talc and saponites (later referred to as “kerolite”). During the geological mapping of the Donskoye, Buranovskoye, and Shelektinskoye deposits, the products of ultramafite hypergenic transformation into disintegrated and leached serpentinites, kerolites, nontronites, and ochers were selected and studied. For this purpose, 44 rock samples were studied via X-ray diffractometric and thermal analyses, supplemented with data from chemical, microscopic, and granulometric determinations. Based on the obtained numerical parameters of the crystalline structure of the weathering products, the thermochemical values were obtained. The hypergenic transformation of the initial minerals and their subsequent transformation were traced. The trace element distribution along the profile of the serpentinite weathering ores is related to the initial material composition of the ultramafites. The accumulation of nickel in industrial concentrations is associated with the nontronite–kerolite zone. X-ray diffractometric analysis can be used as a fast and reliable method for controlling the nickel content of ores and monitoring their mineralogical composition.

The granitoids of the Kalba–Narym batholith and the Irtysh shear zone (ISZ) are among the main geological features of the late Paleozoic Altai accretion–collision system (AACS) in Eastern Kazakhstan. Traditionally, it is believed that late Paleozoic strike-slip faults played a pivotal role at all stages of the development of the AACS, they were supposed to control deformation, magmatism, and ore deposits. This work is devoted to solving the problem of the tectonic evolution of the AACS based on the reconstruction of the thermal history of granitoids of the Kalba–Narym batholith in connection with the Chechek metamorphic dome structure, which is one of the highly metamorphosed blocks mapped within the ISZ. The new geological and geochronological data presented in this work allowed us to establish the sequence of formation of the Kalba–Narym granitoid batholith and link it with the evolution of the Irtysh shear zone (ISZ). It was revealed that in the late Carboniferous–early Permian (312–289 Ma), during the NE–SW compression, the Irtysh shear zone formed as a gently dipping thrust system into which gabbro of the Surov massif intruded. The combined manifestation of magmatic and tectonic processes caused the formation of tectonic mélange with cataclastic gabbro and metamorphic rocks of the Chechek metamorphic dome structure (312–289 Ma). Compression caused the formation of a cover-thrust structure. The thickening of the crust under the probable thermal action of the Tarim plume led to the formation of the early Permian Kalba–Narym batholith (297–284 Ma) within the Kalba–Narym terrane. Denudation of the orogen occurred before the Early Triassic (280–229 Ma). In this way the sequence of formation of the Kalba–Narym batholith and the ISZ is consistent with the concepts of the stages of plume-lithosphere interaction within the AACS under the influence of the late Carboniferous–early Permian Tarim igneous province, but in the cover-thrust tectonic setting.

The article deals with the issues of tectonic zoning of the Paleozoic and Mesozoic-Cenozoic structures of Kazakhstan. The principles of tectonic zoning are outlined, on the basis of which the zoning and indexation of tectonic units of the territory of Kazakhstan was carried out. For this, various data of complex geological and geophysical analysis of Paleozoids were used, including tectonic, structural, stratigraphic, lithological-paleogeographic, petrographic, geodynamic and other studies. A geological and tectonic scheme (model) is proposed that reflects the main tectonic units that make up the structural framework of the Paleozoids of Kazakhstan, consisting of a crystalline basement on which the formation of sedimentary oil and gas basins took place. The main tectonic units of the earth's crust of the territory under consideration are identified and characterized, and the mosaic-block structure of the complexes is shown. The characteristic of the complex multi-stage evolution of the paleozoids of Kazakhstan and its oil and gas regions is given.

Background: Carbonate rocks form subsalt hydrocarbon reservoirs in the Northwestern Margin Zone of the Pre-Caspian Basin. In this context, identifying and analyzing the causes of epigenetic alterations affecting the reservoir properties of carbonate formations is of particular importance, as these alterations influence the optimization of the hydrocarbon exploration and production. These factors underscore the scientific and practical relevance of the present study. Aim: To identify the causes of alteration and to quantitatively assess the reservoir properties of carbonate formations affected by secondary epigenetic transformations. Materials and methods: This study investigates subsalt carbonate reservoirs from oil and gas fields in the Northwestern Margin Zone of the Pre-Caspian Basin. The analysis involved both macroscopic and microscopic examination techniques, supported by a range of laboratory tools, including thermal analyzers, thermogravimetric instruments, and X-ray diffractometry. The method proposed in this paper relies on DTA data obtained during dynamic heating of dolomite, calcite and magnesite, focusing on their thermal decomposition behavior. Mineralogical and compositional control of the reservoir formations was carried out using X-ray phase analysis. Results: A thermal analysis–based technique was developed to quantify secondary calcite in carbonate reservoir formations from subsalt oil and gas fields in the Northwestern Margin Zone of the Pre-Caspian petroleum province. Thermal parameters associated with epigenetic transformations of the dolomite–calcite assemblage was established using representative carbonate samples. These transformations are characterized by the infilling of pore spaces with secondary minerals, leading to reduced porosity and permeability in the affected reservoirs. Conclusion: Accounting for the structural properties of sedimentary rocks described in this study can significantly improve the quality of hydrocarbon exploration. The proposed method provides detailed information on the mineral composition of the reservoir, their filtration-capacity characteristics of carbonate minerals, the crystallinity of their components, lattice properties, and the physical behavior of magnesium, calcium, and other trace elements. Secondary calcite formed through epigenetic alteration of the host rocks has a negative impact on the porosity and permeability of the reservoirs.

Background: Development of a geological framework to substantiate and quantitatively evaluate the hydrocarbon potential of the Balkhash sedimentary basin cover. Aim: Identification of the key estimation parameters for potentially promising hydrocarbon plays (area, thickness, lithological composition) on a qualitatively new geological lithological and stratigraphic base for determining the hydrocarbon potential of the Balkhash sedimentary basin. Materials and methods: Correlation of lithological and stratigraphic sequences of Mesozoic (Triassic-Cretaceous) and Cenozoic (Paleogene-Neogene) deposits in accordance with the stratigraphic charts of the Phanerozoic of Kazakhstan based on the International Chronostratigraphic Scale from 2016 to 2021. Results: The paper investigates the geological structure, zoning, and platform cover of the Balkhash sedimentary basin (BB). During the study, two tectonic units were identified within the BB structure: the West Balkhash and East Balkhash (Lepsin) depressions. Lithological and stratigraphic charts of the Balkhash sedimentary basin have been created and refined to serve as a basis for appraising its hydrocarbon resources. Additionally, prospective hydrocarbon plays have been identified, and their thicknesses have been measured. Furthermore, the analysis of lithological and stratigraphic data has allowed for the determination of the thicknesses, distribution areas of these discoveries, and the organic carbon content within them. These parameters are critical for calculating predicted hydrocarbon resources. Data regarding the development areas of promising BB hydrocarbon plays were obtained from the results of constructing lithological and paleogeographic maps and sections. Conclusion: Based on the developed lithological and stratigraphic model, charts of the Balkhash basin have been drawn up allowing for appraisal of the hydrocarbon potential. The oil and gas potential of the region is estimated to be very low due to the characteristics of the sedimentary cover structure, tectonic activity, and types of possible traps. However, we have identified prospective gas plays that exhibit certain capacities, areas, and organic matter content.