Vol 68, No 5 (2023)

The formation of basalts is a global stage in the evolution of differentiated cosmic body (planet or asteroid) of the Solar System. The paper presents the main chemical and mineralogical features of basaltic meteorites of the SNC, HED group, angrites and lunar mare basalts based on literature data. Despite the differences in the products of basaltic volcanism on different cosmic bodies and significant compositional variations in major minerals of basaltic rocks, most of them belong to low-alkaline basalts, suggesting the prevalence of this type of rocks at least among small bodies of the Solar System. All of them are characterized by the presence of such rock-forming minerals as pyroxene, olivine, and plagioclase, and their spectral characteristics can be used to search for basalts on exoplanets. The main factors affecting the spectral characteristics of atmosphere-free bodies and larger planets with an atmosphere are shown, and the possibility of searching for products of basalt volcanism on exoplanets during future missions is considered.

The paper provides evidence that collisional magmatism related to the Neoproterozoic (880−860 Ma) orogenic event occurred in the southwest of the Siberian Craton. Newly obtained data are presented on the major-component and trace-element composition, U−Pb (SHRIMP II) zircon age, and Sm−Nd isotope composition for rocks of the Gusyanka granitoid massif in the Yenisei fault zone of the Yenisei Ridge. The concordant U−Pb zircon age of the Gusyanka massif is 871 ± 11 Ma indicates that its rocks were formed in the mid-Early Neoproterozoic, simultaneously with the rocks of the Kalama and Eruda massifs in the Tatarka−Ishimba fault system, during the same stage of the collisional events at approximately 880–860 Ma. The calc-alkaline granites, granodiorites, and leucogranites of the Gusyanka massif are classified, on the basis of their high alumina content and trace element composition, as S-type and were derived from a metapelitic source. Many trace-element parameters of rocks of the Kalama and Eruda massifs correspond to those of low-potassium I-type granites, which were most likely derived from mafic rocks and tonalites. The granitoids of the Gusyanka massif, on the one hand, and the Kalama and Middle Tyrada massifs, on the other, differ contrastingly in Nd isotope composition. The source of the former was either metapelites of the Tungusik Group or metasedimentary rocks of the Sukhoi Pit Group, with the involvement of juvenile material. The melts of granites of the Kalama and Middle Tyrada massifs might have been derived from a source with the involvement of an older, possibly Paleoproterozoic, crustal material and a juvenile mafic source. Thus, the orogenic events at 880−860 Ma led to the generation of melts at different levels of the Paleo- to Mesoproterozoic crust of the trans-Angara region of the Yenisei Ridge. The geodynamic history of the region is correlated with the synchronous successions and similar style of tectono-thermal events along the peripheries of the large Precambrian cratons of Laurentia and Baltica, and this is consistent with paleocontinental reconstructions of the close spatiotemporal relations between these cratons, Siberia, and their incorporation into Rodinia.

The paper presents data on quartz-hosted fluid inclusions in commercial ores of various type (veinlet−disseminated and vein) of the Verninskoe gold deposit. The ores of various types were found out to significantly vary in the values of some of their physicochemical parameters of the fluids and in the composition of these fluids. The fluids that formed the gold veins have a somewhat higher initial temperature (356–246°C), a higher density of carbon dioxide in gas inclusions (1.00–0.84 g/cm3), and a higher fluid pressure (3170–1390 bar) than those of the fluids that formed the veinlet–disseminated ores (330–252°C, 0.87–0.54 g/cm3, and 1960–570 bar, respectively). The fluids that formed the gold veins were enriched in CО2, Sr, Ag, Ga, Ge, Mn, Fe, Ni, Sn, Ba, and REE, whereas the fluids that formed veinlet–disseminated mineralization were richer in HCO−3, Br, Sb, V, and Au. This situations may be explained by the interaction of the deep fluid with the terrigenous host rocks in the course of ore deposition. When vein quartz crystallized in relatively wide fractures, the fluid interacted with host rocks and changed not as much as when the veinlet−disseminated ores were formed in narrow fractures. The initial parameters of the fluid that formed the vein quartz were thus the closest to the characteristics of the fluid that transported the ore components, and the comparison of these data with the parameters of the fluids that formed the veinlet–disseminated mineralization demonstrates that they changed in the course of ore deposition. The mineral-forming fluids likely came from a deep-sitting source, and the mineral-forming processes may have involve granitoid-derived fluids.

19–20 апреля 2022 г. в Москве прошел очередной Всероссийский ежегодный семинар по экспериментальной минералогии, петрологии и геохимии, организованный Институтом геохимии и аналитической химии им. В.И. Вернадского и Институтом экспериментальной минералогии им. Д.С. Коржинского РАН. На семинаре были рассмотрены новые результаты экспериментальных исследований по основным направлениям: фазовые равновесия при высоких Т–Р параметрах; образование и дифференциация магм; взаимодействие в системах флюид-расплав-кристалл; гидротермальные равновесия и рудообразование; синтез минералов; термодинамические свойства минералов, расплавов и флюидов; планетология, метеоритика и космохимия; физико-химические свойства геоматериалов; экспериментальная геоэкология; методика и техника эксперимента. В работе семинара приняло участие 200 ученых, треть из них, молодые из 40 Российских научных Институтов и 8 зарубежных организаций, представлено более 140 докладов.