pdf № 367, July New

DOI: 10.19110/geov.2025.7.1

Complex Fe-Ti oxides of the crichtonite group have been identified at the Chudnoe Au-Pd deposit. The species diversity of minerals is determined by the balance between Pb and Sr, and between Zn, Mn and Y. Metarhyolites contain almeidaite, crichto-nite, senaite and minerals of intermediate composition. The composition of almeidaite, which is the richest in zinc, — (Pb_0.44Sr_0.38)_S0.82(Mn_0.65Y_0.30)_S0.95Zn_1.23(Ti_13.67Fe³⁺_5.01)_S18.68O₃₈. The mineral association includes muscovite, hematite, rutile, zircon, aeschynite-(Y), monazite-(Ce), allanite-(Ce). In apobasite hematite-sericite rocks, gramaccioliite-(Y) was found at the contact with metarhyolites. The composition of gramaccioliite-(Y), which is the richest in yttrium, — Pb_0.91(Y_0.50Mn_0.45)_S0.95(Ti_13.13Fe³⁺_6.25 Zn_0.25)_S19.63O₃₈. Associated minerals: muscovite, hematite, titanite, rutile, zircon and allanite-(Ce). Minerals of the crichtonite group are found in the contours of ore zones with vein gold-fuchsite mineralization, but they are localized not in ore veins, but in the rock matrix. The formation of minerals of the crichtonite group is associated with metamorphic processes in rhyolites and contacting basic rocks.

Keywords: almeidaite, crichtonite, senaite, gramaccioliite-(Y), aeschynite-(Y), rhyolites

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DOI: 10.19110/geov.2025.7.2

The findings of a 12-year study of dune complex element development on the Vistula Spit of the Baltic Sea are hereby presented. The focal point of this study is an intensively developing blowout basin in the context of anthropogenic impact. The assessment of landform development over time was conducted by determining geomorphologic changes using digital elevation models (DEMs). These DEMs were obtained by means of topographic terrestrial laserscanning (TLS) measurements or aerial triangulation with a ground control point, accompanied by GPS-RTK measurements. The findings indicated that the rate of desertification was contingent on the composition of plant communities and was sustained by pulse sand supply, facilitated by a network of channels. Grassy areas were the most actively assimilated, exhibiting low roughness, while tree and shrub vegetation, in contrast, exerted a force that directed the wind-sand flow, thereby accumulating a thickness in front of it. The activity of the basin was observed at its peak at the point of connection with the beach. A decline in activity was noted as the basin reached a critical width, at which point the Venturi effect ceased to be effective under the prevailing wind climate.

Keywords: coastal dune, blowout, DEM analysis, eco-geomorphological hazards, relief transformation vector

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DOI: 10.19110/geov.2025.7.3

The effect of sample preparation on the accuracy of carbon dioxide and water determination in fluid inclusions contained in quartz by pyrolytic gas chromatography is considered. It is established that careful control of quartz at all stages of sample preparation is necessary to obtain correct results. It is shown that exclusion of the stage of preliminary selection of quartz grains under a binocular microscope, even in the case of studies of high-purity, transparent quartz, can lead to significant errors in determining the content of carbon dioxide and water. It is established that in cases when quartz grains contain intergrowths with inclusions of magnetic and weakly magnetic minerals and/or are covered with iron oxide films, standard sample preparation procedures including quartz crushing, selection of a monomineral fraction, treatment with heated acid solutions, thorough washing in bidistilled water with subsequent drying, are insufficient when using pyrolysis as a method for opening inclusions. In this connection, to correlate the obtained data with the composition of fluid inclusions in such samples, it is recommended to include an additional stage in sample preparation — the electromagnetic separation.

Keywords: gas chromatography, quartz, gas-liquid inclusions

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DOI: 10.19110/geov.2025.7.4

The article presents the results of a two-year study of the composition of quarry waters at a gypsum deposit located in the Kholmogory District of the Arkhangelsk Region. Systematic monitoring included determining the physicochemical parameters in key process zones: the quarry water collector (sump) and the settling pond of the treatment facilities. To obtain the analytical base, standard methods were used: GOST 31957-2012, PNDF 14.1:2:4.157-99, and others. It was found that the dry residue indicator of water varies in the range of 1190—6700 mg/dm³ with pronounced seasonal dynamics: maximum in spring (March) and minimum in summer (June). The dominant component is sulfate ion (up to 3700 mg/dm³), which is typical for gypsum deposits. Exceedances of the maximum permissible concentrations for river waters used for fishery and/or drinking purposes were revealed for the content of sulfates and strontium, and occasionally for magnesium, iron, zinc, copper, cadmium and aluminum. Efficiency of treatment facilities was demonstrated, ensuring a reduction in pollutant concentrations to 29 %. The results are consistent with the data of other researchers, but demonstrate the specificity of the territory under consideration – increased content of sulfates and strontium and slow sedimentation of suspended matter. The obtained data are of interest to mining enterprises, environmental organizations and scientific institutions dealing with the problems of ecology of mining production.

Keywords: gypsum quarry, quarry water, sulphates, strontium, environmental monitoring, treatment facilities

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