At 750°C and a pressure of 1 kbar, an experiment was carried out simulating the contact-reaction interaction of calcite and a highly evolved fluorine-containing granite melt. The water content in the system did not exceed 10% of the dry charge mass. The possibility of interaction between magmatic melt and calcite is shown. The experimental products contain a zoned column composed of liquid phases and crystalline minerals. In the apocarbonate part, the newly formed phases are cuspidine, quartz, wollastonite, grossular, and a non-crystalline carbonate–fluoride phase LCF. The mineral assemblages in the zones of the apocarbonate part of the column vary depending on the ratio of CO₂ and HF activities. In the silicate part, aluminosilicate glass, alkali feldspar, and plagioclase of variable composition were found. Silicon and fluorine are intensively transferred from the silicate to carbonate part, and a small amount of calcium is transferred in the opposite direction.

The feasibility of producing high-quality zinc phosphate cement based on a frit-sintered mixture of ZnO, SiO₂, MgO, and Bi₂O₃ oxides, with the addition of phosphorous slag and an aqueous solution of orthophosphoric acid as the mixing liquid, was demonstrated. The raw materials used for zinc phosphate cement preparation were investigated using various physicochemical analysis methods. It was found that the phosphorous slag contains silicon oxide (37.6%), aluminum oxide (4.49%), calcium oxide (42.4%), magnesium oxide (2.19%), as well as fluorine (1.94%) and calcium fluoride (4.91%). The slag predominantly consists of an amorphous glassy phase with minor inclusions of crystalline components. During the sintering process, the addition of 1.5–3.0 wt.% phosphorous slag to the frit promotes the formation of low-melting eutectics due to the presence of fluorides, resulting in a 100 °C reduction in the sintering temperature. An optimal zinc phosphate cement powder composition was developed, comprising: ZnO—83.0%, MgO—9.0%, SiO₂—3.5%, Bi₂O₃—3.0%, and phosphorous slag—1.5%. The resulting sintered product exhibited a whiteness of 97.8%, which exceeds that of the reference sample by 2.6%. Upon mixing the powder with the mixing liquid, zinc ions are released first, initiating a chemical reaction that leads to the formation of zinc, magnesium, and aluminum phosphates. The compressive strength of the resulting composite cements ranged from 101.8 to 111.9 MPa, fully complying with the requirements for cement grade as specified in GOST 31578-2012.

The results of two experiments on the interaction of fluorine-bearing granite melt and calcite with the same initial composition of the dry charge and diff

The article is devoted to the study of spatiotemporal variability of the plumes of the Terek and Sulak rivers flowing into the Caspian Sea and to the determination of the three-dimensional structure of the plumes based on a joint analysis of satellite data and concurrent in situ measurements. In the study, high spatial resolution visible data from Sentinel‑2 MSI and Landsat-8, -9 OLI/OLI-2 satellite sensors were used. In situ measurements of the main plume parameters were made in June 2023, from a small vessel, concurrently with the satellite survey. As a result of satellite monitoring of the Terek and Sulak estuarine zones for the period 2014–2022, it was determined that the 73-km-long coastline of Dagestan north of the city of Makhachkala is potentially exposed to pollution entering the sea with waters of these rivers. An analysis of the satellite images showed that there is a pronounced spatial asymmetry in the direction of plume spreading. For both rivers, the dominant spreading direction over a large time interval is southeast. A seasonal variability of Terek and Sulak plumes signatures in satellite images was revealed. Based on satellite data and concurrent in situ measurements in June 2023, the three-dimensional structure of the Terek and Sulak plumes was obtained and the spatial distributions of the main parameters, such as temperature, salinity, turbidity and chlorophyll-a concentration, were determined. It was found that the depth of river water penetration does not exceed 1.5–2 m and, regardless of the amount of suspended matter carried with river runoff and river discharge, the bulk of the suspended matter is deposited in the same localized area, within a distance of about 500 m from the shore. On the basis of XRD analysis of water samples taken at the stations nearest to the river mouths and at plume boundaries, the mineral composition of suspended matter and its variation in different plume areas were determined. Repeated coincidence of the boundaries of the area affected by river water, established from satellite data and measured in situ, makes it possible to confidently use remote sensing methods for monitoring estuarine zones without involving in situ data.

The paper summarizes the results of a 2019–2024 study of river plumes focusing on the determination of water turbidity and suspended particulate matter (SPM) concentration from satellite data, their validation by in situ measurements, and estimation of mineral composition of the SPM. The objects of the study were the plumes of the Sulak and Terek rivers, which flow into the northwestern part of the Caspian Sea, and the plume of the Mzymta River, which flows into the northeastern part of the Black Sea. The satellite data used were high spatial resolution data from Sentinel-2 MSI (Multispectral Instrument) and Landsat-8, -9 OLI/TIRS (Operational Land Imager / Thermal Infrared Sensor) sensors. Synchronously with the satellite observations, in situ measurements using water turbidity sensors and water sampling were made to determine plume water turbidity, SPM concentration and mineral composition. X-ray phase analysis of samples collected from different parts of the plumes was carried out to quantify the SPM mineral composition and its change with river water spreading out to sea. Having similar SPM mineral compositions, mainly comprising three groups of minerals: anhydrous aluminosilicates, clay minerals and carbonates, the plumes are characterized by significantly different SPM particle size distributions in the mouth zones. According to the averaged data for the entire observation period, the change in the mineral composition in different parts of the plume is best manifested for the Terek and Mzymta rivers. Toward the edge of their plumes, the relative proportion of clay minerals increases, while the content of quartz and feldspars becomes significantly lower. No such pattern is observed for the Sulak River. The ratio of clay and aluminosilicate material either practically does not change in different parts of its plume or changes in an arbitrary direction. A comparative analysis between turbidity and mineral composition was attempted. Changes in SPM mineral composition are accompanied by significant changes in water turbidity determined both in situ and from satellite data.

This work is devoted to the investigation of rare-metal granites associated with anorthosite–rapakivi granite rock complexes. This article evaluates the physicochemical conditions that governed the formation of a rare-metal granite dike. It also explores assumptions regarding the geological characteristics of the magmatic chamber, describes evidence for liquid immiscibility, and addresses the post-entrapment evolution of hydrosilicate liquids. In addition, new mineralogical data are presented. The methods employed include optical and electron microscopy, Raman spectroscopy, secondary ion mass spectrometry, laser ablation inductively coupled plasma mass spectrometry (LA–ICP–MS), melt inclusion homogenisation experiments, and fluid inclusion study. The investigated granitic dike formed under low pressure (60–110 MPa) and temperatures of about 580–600 °C, from a specific volatile-saturated magma rich in H₂O (up to 16.76 wt% in quenched hydrosilicate liquid products) and in F (up to 4.16 wt%) and Li (up to 3804 ppm), as indicated by homogenised melt inclusions. At the time of emplacement, a silicate melt, a probable Ca-fluoride melt, an Mg-Fe Al-Si-rich hydrosilicate liquid (either mutually soluble with or mixed with the inferred Ca-fluoride melt), and an essentially aqueous fluid coexisted. Depolymerisation of the silicate melt and the presence of complex ions probably promoted the dissolution and transport of high field strength elements (HFSE) and large ion lithophile elements (LILE) elements by the Mg-Fe Al-Si-rich hydrosilicate liquid. During the final stage of evolution of the granitic magmatic system, Mg behaved incompatibly because of its negligible partitioning into mica; rather than accumulating in the silicate melt, it entered the hydrosilicate liquid as a major component. The residual silicate melt consequently attained even lower Zr/Hf, Nb/Ta, and Y/Ho ratios than the studied rock.