Geochemistry International
ISSN (print): 0016-7525
Founders: V.I. Vernadsky Institute of Geochemistry and Analytical Chemistry, Russian Academy of Sciences
Editor-in-Chief: Yuri Aleksandrovich Kostitsyn, Academician of the Russian Academy of Sciences, Doctor of Geological and Mineralogical Sciences
Frequency / Access: 12 issues per year / Subscription
Included in: White List (2nd level), Higher Attestation Commission List, RISC
Media registration certificate: No. FS 77 – 83947 dated 09/30/2022
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Vol 71, No 1 (2026)
Articles
Formation and Evolution of the Spinel Anorthosites on the Moon: Experiment and Observation on Lunar Highland Meteorites Dhofar 025, Dhofar 311 and NWA 11303
Abstract
Detection of a new type of rocks on the lunar surface spinel anorthosites — aroused great interest in the petrogenesis of spinel-bearing rocks. In this work, we searched for and studied Mg-Al spinel in the lunar highland meteorites Dhofar 025, 311 and NWA 11303 and conducted an experiment modelling the formation of spinel anorthosites as a result of post-impact melting of troctolites/troctolite anorthosites. It has been established that in this case the formation of spinel anorthosites is possible only if the troctolite melt is preserved at a shallow depth with the possibility of its rapid crystallization. Spinel is mainly present in the studied meteorites in the form of monomineral fragments formed as a result of a rock disintegration during impact processes. Such rocks are spinel-bearing troctolites and possibly deep-seated rocks of the lunar crust, spinel cataclasites, which fragments are present in the meteorites Dhofar 025 and 311. The only fragment of spinel anorthosite was found in the meteorite NWA 11303, however, it differs in mineral composition from the rocks predicted by orbital data. The similarity of the spinel compositions of different rock types does not allow us to clearly identify the sources of fragments of spinels in lunar breccias. The study of the mineral composition and textural features made it possible to trace the main stages of the evolution of spinel rocks in impact melts of highland composition, which are expressed in shock-induced melting at the grain boundaries in the rocks, appearance of resorbed edges at the contact of spinel fragments with an impact melt, and formation of rounded zonal grains at the final stage.
Geochemistry International. 2026;71(1):5–27
5–27
Structure and Physicochemical Properties of Crystals with Bradleyite Structure under Pressure
Abstract
In this work, a first-principles study of the crystal structure, chemical bonding, and vibrational spectra of bradleyite Na3Mg(PO4)(CO3) under pressure is performed. The basis of a linear combination of atomic orbitals and the gradient PBE and PBEsol functionals of the CRYSTAL software code are used. Satisfactory agreement between the calculated and measured lattice parameters is observed. The mechanisms of chemical bond formation are studied using the charges and populations of the overlapping electron shells of atoms, which are estimated using the Mulliken scheme. The parameters of the equation of state in the Birch-Murnaghan form are determined, the bulk modulus of which is used to calculate the Grüneisen mode parameters characterizing the dependence of the infrared absorption and Raman spectra on pressure. Bands characteristic of vibrations of the [CO3] and [PO4] molecular groups with a pronounced contribution from individual groups of oxygen atoms are distinguished in the spectra. The possibility of the existence of Na3Zn(PO4)(CO3) and Na3Pb(PO4)(CO3) crystals in the bradleyite structure is shown.
Geochemistry International. 2026;71(1):28–48
28–48
Fluid Gas Composition during Hydrothermal-Metasomatic Alteration of Komatiites in the Kostomuksha Greenstone Structure (Western Karelia, Russia)
Abstract
This study reports data on the gas composition of the mineralizing fluid, which is associated with hydrothermal alteration of Mesoarchean komatiites in the Kostomuksha greenstone structure (Western Karelia, Russia), and responsible for the formation of the soapstone Ozerki deposit and the Pentinsuo occurrence. Gas chromatographic analysis identifies H2O (60.85–94.49 mol. %) and CO2 (3.11–33.38 mol. %) as the dominant fluid components. Soapstone (carbonate-chlorite-talc rocks) formed via interaction with oxidized fluids (CO2/(CO2+CO+H2+CH4) = 0.64–0.96), with a significant CO2 molar fraction (ΧCO2 = 0.082–0.334). Along with the high carbon dioxide content in the fluid, the primary factors controlling soapstone localization were the high magnesium content of the ultramafics and their tectonic deformation.
Geochemistry International. 2026;71(1):49–71
49–71
Biogenic Elements in the Surface Waters of Bolshoy Solovetsky Island
Abstract
The paper presents the results of the study of biogenic elements (N, P and their compounds, as well as Si) concentration in surface waters of 23 lakes of Bolshoy Solovetsky Island (Arkhangelsk region) in the White Sea during the summer and winter seasons. In summer, samples were taken at the horizon (0.5 m) and above the thermocline to characterize surface waters (epilimnion). In winter, sampling was carried out at a 1 m horizon and under a subglacial thermocline. Characteristics of lake basins and their catchment areas were obtained (including openness, waterlogging of the catchment). Lakes were classified by mineralization, color and degree of humification. It was found that the concentration of biogenic elements in surface waters of most of the studied lakes is below the lower limit for optimal development of algae, which is related to both atmospheric nutrition of lakes and underlying rocks and soils. The ratio of elements Ntot/Ptot showed that phosphorus is the limiting element in most of the studied lakes. Grouping of lakes according to the content of biogenic elements in surface water has established minimal differences between lakes of the western and southern channel systems. It was shown that lakes Valdai, Shchuchye, Sredny Perth and Pitievoye can be used as model objects for studying/predicting ecosystem response to external impacts during long-term studies.
Geochemistry International. 2026;71(1):72–92
72–92
TABLE OF CORRESPONDENCE FOR 2025 ARCHIVAL AND CURRENT DOI
Abstract
В связи с непредвиденными обстоятельствами произведена замена DOI статей с префиксом Российской академии наук за 2025 год. В первых выпусках журналов РАН за 2026 год размещена информация о замене цифрового идентификатора на действующий DOI.
Geochemistry International. 2026;71(1):93–100
93–100