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The metamorphic rocks in the northeastern Taimyr region are a consequential result of its complex geologic history. Series of metamorphic processes were associated with the formation of lode copper and noble-metal mineralization. The aim of this study is to investigate the type and degree of metamorphism of the host basic volcanic rocks in the ore cluster. We have identified three stages of metamorphic process: The first stage led to the formation of actinolite and sodium plagioclase paragenesis (with its chemical compositions corresponding to temperature of about 400 °C); the second stage resulted in the crystallization of hornblende, plagioclase, spessartine-almandine garnet, biotite, feldspars (oligoclase-andesine and K-Ba types), and various Fe-Ti phases (mineral geothermometers show the highest temperature range of 450-600 °C), and the final stage produced clinochlore, pyrite, and fluorapatite (330-290 °C according to the Al^IV contents in chlorite). We interpret the studied rocks as hornfels based on the highly discordant contours of the metamorphic aureole, the compositions of garnet (spessartine is a predominant component), and the K-Ar ages of biotite (253 ± 5 Ma) and plagioclase (239 ± 8 Ma), which coincide with the time of late Paleozoic-Mesozoic postcollisional granitoid magmatism. The absence of schistosity, the disequilibrium assemblages, and the abundance of volatile-rich minerals (containing F^-, OH^-, and SO₄^2-) also indicate their contact origin. The discovered aureole includes the known Cu-Au-Ag veins and metasomatic occurrences, the age of which is therefore late- or postmetamorphic. We confirm the earlier hypothesis of our colleagues about the impact of a concealed granite massif on the host rocks and consider the high metamorphic grade to be a natural boundary for the ore cluster.

The behavior of Ag in the oxidation zone of the Kyzyk-Chadr gold-sulfide-quartz deposit (Tuva Republic, Russia) is investigated. The primary focus is on the mechanisms of Ag differentiation under supergene conditions, including the formation of secondary minerals and silver incorporation as an isomorphic impurity into other phases. It was established that Ag in the oxidation zone forms chalcogenides (acanthite, petrovskaite, uytenbogaardtite, and jalpaite) and halides (iodargyrite, bromargyrite, and mayersite), which are associated with malachite, chrysocolla, brochantite, quartz, and iron hydroxides. Electron probe microanalysis reveals Ag concentrations in secondary copper sulfides (covellite, chalcocite, yarrowite, etc.) of ≤0.7 wt.%. Optimization of the microanalysis parameters to enhance resolution lowers the detection limit, enabling the determination of low Ag contents in chalcopyrite (≤0.05 wt.%) and bornite (≤0.09 wt.%). The sources of Ag are primary Ag tellurides and selenides, as well as primary and secondary Cu sulfides that decompose during the oxidation. Computer thermodynamic modeling is used to describe the behavior of Fe, Cu, and Ag during the progressive oxidation of primary assemblages (bornite, chalcopyrite, and acanthite). The Eh-pH conditions controlling mineral migration and reprecipitation are calculated, and the element concentrations required for the formation of secondary phases were estimated.

We report results on the age estimates of the Paleogene diatom datums derived from the magnetostratigraphy at the marine Cenozoic stratigraphic section of the Kvachina Bay, West Kamchatka. Based on a direct correlation with the Geomagnetic Polarity Time Scale, it was possible to determine the age of such levels in the interval between Subchron C13r (35.10-33.73 Ma) and Subchron C9r (27.86-27.44 Ma). Of greatest interest are the dates of the first and last occurrences of Lisitzinia ornata (27.71 Ma and 27.54 Ma respectively), and the first occurrence of Rocella gelida (27.49 Ma). This is the first experience of absolute age estimates of Oligocene diatom biohorizons based on magnetostratigraphy not only in Kamchatka sections, but in the North Pacific region in general. A comparison was made between the obtained age estimates and those published in the literature based on the study of deep-sea cores in various regions of the World Ocean.

We have estimated the proportion of sorbed water converted to ice and hydrate during the interaction of wet sand samples with methane by using the nuclear magnetic resonance (NMR) relaxometry method. There is a thin film of strongly bound water in small pores at the rock-fluid interface. This water does not freeze at the subzero temperatures achieved during the experiment; its amount remains constant without regard to the water content in a sample. We have calculated the amounts of strongly bound water and water converted to ice and hydrate for all samples. Based on the established hydrate stoichiometry, we have calculated the amount of methane converted to hydrate. Analysis of the obtained data has revealed the optimal water content in a sample, which results in the greatest amount of hydrate formation.

The unique relationship between induced polarization parameters and the structure of interface and pore space in rocks sustains considerable interest in applied science, driving the continuously expanding range of application of this method. The physicochemical theory of induced polarization in rocks contains significant gaps, which stem from the complexity of the processes generating secondary electric fields within rocks. To date, laboratory investigation results remain the primary source of new knowledge about the mechanisms and processes occurring in rocks under the influence of an electric field. Over the past decade, several new hypotheses, mechanisms, and models of induced polarization in rocks containing electron-conducting mineral inclusions have been proposed; their key features are described in our article. These hypotheses are actively discussed and used for interpreting induced polarization data obtained in laboratory studies and field tests. We present the results of an experimental study of induced polarization at the shungite - pore moisture interface, conducted on a synthetic capillary model of rocks containing an electron-conducting mineral inclusion. Based on voltammetric measurements, the principal characteristics of shungite polarization in an aqueous NaCl solution are established. The magnitude of exchange currents, the dynamics of interfacial polarization at different current densities, and the features of interfacial potential relaxation are estimated. Our study features the first presentation of measurements of electric currents flowing within the model and inside the shungite inclusion - the induced polarization currents. It is proven that the relaxation of the electric field in the model and that of the induced polarization currents exhibit identical dependences. The proportionality between the polarization intensity of the shungite inclusion and the normal current component at the shungite - pore moisture interface is experimentally confirmed. The resulting materials point to the dominant role of the electrode polarization mechanism for electron-conducting mineral inclusions in rocks. A description of the most probable induced polarization mechanism at the mineral inclusion - pore moisture interface in rocks is provided.

This study demonstrates the practical feasibility of high-precision in-flight measurement of magnetic fields from remote radio transmitters, including the use of unmanned aerial vehicles. The proposed method is based on calculating the Euclidean norm of the full complex magnetic field vector, which eliminates any dependence of the result on the orientation of the measurement system. To compensate for primary field instability, normalization is performed using a synchronized signal from a stationary base receiver. Further accuracy is achieved through pre-flight sensor calibration and spatial data smoothing during processing. Test measurements demonstrate good result reproducibility, with a discrepancy of less than 0.5% of the signal level. Moreover, magnetic field anomaly maps obtained at different altitudes show strong correlation both with each other and with archival data from ground-based inductive electromagnetic surveys.

The nothospecies Galatella × tzvelevii Vasjukov et Saksonov (Asteraceae), derived from a hybridization of G. biflora (L.) Nees × G. villosa (L.) Rchb. f., was described in 2015 from a single flowering specimen in the Samara Region. While working at the I.I. Sprygin Herbarium (RKM) of Penza State University, we discovered another specimen of this nothospecies, designated here as the epitype of the name of this taxon. Characters supplementing the morphological description of the nothospecies given in the protologue, as well as characteristics of the parental species, are discussed. A new locality for G. × tzvelevii from the Republic of Bashkortostan is also presented.

The pine and small-leaved pine grass forests of the North-Western Caucasus are proposed to be considered as part of a special subzonal geographical type - the European-Siberian hemiboreal forests. The results of the analysis of the spectrum of phytocenotic groups demonstrated the highest importance of light-depending mesophilous species of subalpine-forest and “betular” (related to birch forests) phyto-cenoenotic elements, as well as the important role of subalpine species along with the weak participation of shade-tolerant nemoral plant species. The results of the geographical analysis of the floristic composition revealed the predominance of widespread species (of Eurasian, European-Siberian and West Palearctic chorological groups), as well as endemic Caucasian taxa. According to the proposed concept of the genesis of the Caucasian hemiboreal forests, the high level of endemism is a consequence of their autochthonous floro-genesis at the upper boundary of the forest belt in the Pliocene. At the same time, the significant participation of European-Siberian, Western Palearctic and Eurasian chorological groups is the result of active migrations of plant species in hemiboreal forests predominated during the Quaternary period in forest and forest-steppe zones of Northern Eurasia.

The article contains personal memories of meetings with the outstanding botanist Andrey Pavlovich Khokhryakov (1933-1998), which had a significant influence on the author’s professional path. It describes striking moments of joint expeditions, seminars, and scientific discussions that reveal the unique talent and personal qualities of the scientist. The article provides information about Khokhryakov’s contributions to various fields of botany and emphasizes the significance of his ideas and work for modern science.

The review of publications (106 sources) on the history of the Central Siberian Botanical Garden of the Siberian Branch of the Russian Academy of Sciences for the period from the moment of the first newspaper appeals about the organization of the botanical garden in Novosibirsk (1939, 1945) to the present is given. The publications are organized into blocks on general history, memorial dedications, the history of scientific fields and/or laboratories, and the memoirs of employees. The review of historical literature makes it possible to evaluate the contribution of four generations of researchers and staff of the Botanical Garden to the organization of botanical science in the conditions of the Soviet period, during the “perestroika period” and in the first decades of the new century. The collected materials are the basis for the work of the “Botanical Museum of Siberia” to preserve the history of the Central Siberian Botanical Garden SB RAS.