No 5 (2025)

The article presents new data about mineralogy of manganesesilicate rocks, contact-metamorphosed analogues of siliceous-rhodochrosite rocks. Of particular interest to these rocks is the presence of Au–Ag–Pd–Pt mineralization. The purpose of the research was to obtain new data on the mineralogy and origin of the little-studied manganesesilicate rocks of the Mokrushinskaya area of the Olginsky district. As a result, new information was obtained for spessartine, pyrophanite, cobaltine, and costibite from manganesesilicate rocks, and a group of minerals and mineral varieties were identified and studied that are rare in nature and previously unknown in Sikhote-Alin (pyroximangite, manganocummingtonite, manganogrunerite, nickeline, zigenite, cobalipentlandite, rich in Co pentlandite, parkerite, compound PbBi₆(Te₆S)₉, native silver and other minerals). It is shown that the parageneses of manganesesilicate rocks of the Sikhote-Alin and their constituent rock-forming minerals differ in composition depending on the area of their distribution. These features reflect differences in the chemical composition of protoliths of manganese silicate rocks, which indicates significant regional variations in the facies conditions of accumulation of Mn-rich metalliferous sediments. It has been established that manganesesilicate rocks are composed of various associations. The earliest ones were formed at the temperature ~500–550 °C as a result of contact metamorphism during the introduction of the Vladimir granitoid massif. Later associations were formed at the temperature ~250–350 °C as a result of the episodic circulation of the mobile fluid phase in the zones of increased permeability against the background of cooling of the Vladimirsky massif.

The paper examines the features of the material composition of subcoal, coal-bearing and supracoal deposits in connection with the problem of metal content of the Pavlovskaya Depression located on the southern edge of the Khankaisky median massif in Primorsky Krai. The tested stratigraphic levels are characterized by a similar composition, but differ in the percentage content of the main and accessory minerals (quartz, kaolinite, zircon, garnet, anatase, leucoxene, ilmenite and rutile, etc.). Morphological and compositional features of common accessory and ore minerals are established. As a result of the study, previously published data on the forms of occurrence and transfer of germanium, tungsten, antimony, arsenic and rare earth elements (REE) in sedimentary deposits and the weathering crust of the Pavlovskaya Depression were confirmed, which indicate the hypergene genesis of the Spetsugli germanium-coal deposit. The source of the rare element group entering the coals were greisenized granites of the basement; for Ge, W, As, Sb the hydrogenic form of transfer is confirmed, for REE the hydrogenic-clastogenic form. The source of the rare particles of flaky gold found in the Neogene deposits has not yet been established.

This article examines the impact of accumulated mining and processing waste (tailings) on the quality of groundwater used by the population of the Yaroslavsky settlement in Primorsky Territory for non-centralized water supply. It provides an in-depth analysis of the hydrogeochemical processes that determine the migration of pollutants from fluorite ore tailings into groundwater horizons. The study reveals that the mineralization of the tailing dump’s waters has increased and they contain toxic components (Be, As, Li, Cd, etc.) belonging to hazard classes 1–2. A toxicological risk assessment was carried out, revealing a slight exceedance of the maximum permissible concentration of Mn in one of the water supply sources, while concentrations of other monitored elements are below normative levels. Methods and indicators for assessing groundwater pollution (e.g. comparison with sanitary norms and integral pollution indices) are described. Recommendations for monitoring and risk management are proposed, including continuous water quality control, tailings dam reinforcement and emergency situation prevention. It is concluded that, currently, the quality of the studied groundwater meets sanitary requirements. However, there is still a potential risk of contamination in the event of tailings dam instability or extreme natural occurrences.

A crustal earthquake and its aftershocks that occurred in Japan (Mw = 7,5, 01.01.2024) were studied to make measurements and analyze the parameters of strong ground motion, including the Arias intensity. The latter is one of the key physical parameters used in engineering seismology. The level of the Arias intensity is directly connected with the stress drop in an earthquake source. Therefore, developing and calibrating a magnitude scale that would take into account not only fault dimensions, but also the stress drop in an earthquake source is a vital task of seismological observations. In this paper we present our test results of a new magnitude scale (MIa3) based on a modified Arias intensity. The scale was calibrated to medium and moderate earthquakes in the target area (M ~5). The high efficiency of the proposed scale is evidenced by the magnitudes, determined through the new method, that are almost consistent with the moment magnitude (Mw).