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Studying early Precambrian astroblems is complicated by their localization in structural and compositional complexes that underwent superimposed metamorphism and tectonic processing. Back in the 1980s, seven sites with occurrences of breccias and other rocks resembling impact structures were identified as potentially diamondiferous impact structures within the Karelian-Kola region. But at present, only two astroblems are known in the region: Janisjarvi of 725 ± 5 Ma and Suavjarvi of ~2400 Ma. In the Kola part, impact origin is assumed for two objects: the Javrozero circle structure in the Tanaelv belt and the Jarva-varaka layered massif in the Monchegorsk ore area. The most promising structure to be an astrobleme with serious signs of impact origin is the Paleoproterozoic Jarva-varaka massif. According to geological, petrochemical, and geochemical characteristics of rocks the Jarva-varaka massif is most similar to the 1.85 Ga Sudbury structure (Canada), for which an impact origin was assumed. Shock metamorphism of the Jarva-varaka massif was manifested in amorphization of zircon from the country rocks with formation of plagioclase and sillimanite glasses in inclusions, as well as planar deformations in quartz.

The Monchetundra massif is located in the north-eastern Fennoscandian Shield and refers to Paleoproterozoic massifs of the East-Scandinavian Large Igneous Province. The general section of the massif comprises two parts, the lower norite-orthopyroxenite and the upper mafic zones.The lower zone is of great interestdue toits associated industrial platinum group elements (PGE) mineralization. The structure and peculiar features of rocks in the lower zone were studied using a drill core from the borehole MT-70 in the south-eastern slope of the Monchetundra massif intersecting the ore zone 1 of the Loypishnun deposit (according to the CJSC Terskaya Mining Company data). A comparison of the barren and ore-bearing varieties of norites and pyroxenites in the Loypishnun deposit shows that the ore samples have the lowest negative &epsilon, Nd values, a relatively more differentiated distribution spectrum with the Light rare earth elements (LREE) dominating over the Heavy REE (HREE), Eu/Eu* &ge, 1, and a higher mean content of alkali and large-ion lithophile elements (Ba, Rb, and Cs). New geochemical data indicated an origin of magmas for rocks from a layered series in the Loypishnun deposit by a high degree of melting of a LREE-rich source with a low mean content of REE. Negative &epsilon, Nd values, low ISr values, and a marked negative Nb indicate that the crustal material affected the evolution of rocks in the lower zone of the massif more than in the upper zone. The formation of ore bodies in the Loypishnun deposit was governed by the crust-mantle interaction, magmatic differentiation, and association with the most differentiated varieties, and by further concentration of the ore at the late and post-magmatic stages in a highly permeable environment for fluids in the Monchetundra fault zone.

The approximate solutions of the equations of steady- and unsteady-state mass transfer in apparatuses with continuous phase contact have been obtained and used as the basis of proposing a method for calculating packed apparatuses with turbulent liquid flow under gas displacement conditions. A method of estimating the longitudinal diffusion coefficient in a packed bed and a method of controlling the mass-transfer process in apparatuses with continuous phase contact have been developed.

The rocks and minerals of the Kolvitsa massif are studied by complex isotopic–geochronological and geochemical (U–Pb, Sm–Nd, REE contents of zircons) methods. The isotopic U–Pb age (2448 ± 5 Ma) of single zircon grains, which were extracted from metagabbro of the block, is consistent with previous data on the rocks of the Kandalaksha anorthosite block. According to Sm–Nd studies of minerals of the metamorphic complex (apatite, sulfide minerals, garnet) and rocks of the block, the age of their metamorphic transformations is 1985 ± 17 Ma. The calculated temperature of the closure of the U–Pb system and crystallization of zircon of metagabbro of the Kolvitsa massif is 778°C. The REE patterns of single zircon grains indicate their magmatic origin.

The first ever comprehensive geochemical data on the Kontay intrusion, polar Siberia, demonstrate that the intrusion is profoundly differentiated and shows geochemical features typical of intraplate magmatism. The age of the intrusion is Early Paleozoic. The paper summarizes literature data regarded as circumstantial evidence that a large magmatic intraplate (perhaps, plume-related) province of Early Paleozoic age may occur in the northern part of the Siberian Platform, whose only component found as of now is the Kontay intrusion. The intrusion is demonstrated not to possess any precious-metal (Ag–Pd) ore potential, contrary to what was surmised previously.

Data on gold ore objects in the Strelna Greenstone Belt in the southeastern Kola Peninsula are presented in the paper. The studied Vorgovy and Sergozero ore occurrences are localized in the zone of tectonic contact of the Neoarchean complexes making up the greenstone belt and the volcanic–sedimentary sequences of the Paleoproterozoic Imandra–Varzuga Zone. The Vorgovy gold occurrence is related to stockwork of carbonate–quartz veins and veinlets hosted in a biotite gneiss transformed into chlorite–sericite–quartz metasomatic rock with pyrrhotite–arsenopyrite dissemination. The Sergozero occurrence is localized in amphibolites corresponding to komatiitic and tholeiitic basalts hosted in biotite gneiss (metapelite). Mineralization is confined to the zone of tectonized contact between komatiitic and tholeiitic basalts, where it is controlled by a strip of metasomatic biotite–calcite rock with gersdorffite–arsenopyrite dissemination. The native gold grains medium to high in fineness are up to 0.1 mm in size and mainly localized at the contact of arsenopyrite and gersdorffite with gangue minerals. Gold mineralization is of superimposed character, and, as indicated by isotopic geochronology, was formed at the retrograde stage of the Svecofennian regional metamorphism. Comparison of ore occurrences localized in the Strelna Greenstone Belt with gold deposits in greenstone belts of the western Fennoscandian Shield and the Superior Province in Canada allows us to suggest a high perspective of the entire Strelna Belt for gold.

On the basis of U–Pb, Rb–Sr and Sm–Nd isotopic data, it is shown that formation of uranium mineralization in the Paleoproterozoic Salla-Koulajarvinsky belt (Northern Karelia) was a long-lasting mult-stage process that developed over more than 1 Ga: from the Paleoproterozoic to the Paleozoic. The first stage, 1.75 Ga ago, corresponds to the Svekofennian metamorphic event—regional albitization. The process was dated by the Rb–Sr (isochronic age of albitites is 1754 ± 39 Ma) and U–Pb methods (the age of rutile is 1756 ± 8 Ma). At this stage, with a lower temperature limit of 400–450°C, conditions were favorable for the mobilization and migration of uranium, but not for its deposition in minerals. The second stage, 1.62 Ga ago, was a time of alteration of rocks at the regressive stage of the Svekofennian metamorphic event, when carbonate and chlorite rocks formed after albitites. The age of this stage was estimated as 1627 ± 42 Ma according to ThO2, UO2, and PbO contents in uraninite. Probably, the deposition of uraninite took place at this stage at temperature not higher than 300–350°C. The final, third stage, 385 Ma ago, corresponds to the Paleozoic tectonic activation and formation of Caledonian alkaline intrusions. Uranium minerals were probably redeposited at this stage; the U–Pb age of brannerite is 385 ± 2 Ma.

Consideration is given to mathematical modeling of the process of nonstationary liquid–liquid extraction in apparatuses with free motion of a dispersed phase. Solutions of nonstationary equations of transfer of momentum and mass in the boundary layer on the droplet and inside the droplet near the phase boundary are given. Equations for calculation of the coefficients of mass transfer and concentration of the extracted component are obtained. A comparison is made of the calculated data and experimental results in extracting various liquid mixtures.

A procedure is proposed for development of computerized training simulators for the modeling of production systems based on functional blocks. An algorithm is proposed for development of computerized training for edification of industrial personnel working in the hydrocarbon-pre-debutanization block. Simulation results are presented.

The dike-vein complex of the Moncha Tundra Massif comprises dolerites, gabbro-pegmatites, and aplites. The dolerite dikes are classified into three groups: high-Ti ferrodolerites, ferrodolerites, low-Ti and low-Fe gabbro-dolerites. The U-Pb age of the ferrodolerites is 2505 ± 8 Ma, and the amphibole-plagioclase metagabbroids hosting a ferrodolerite dike are dated at 2516 ± 12 Ma. Data on the U-Pb isotopic system of zircon from the gabbro-pegmatites and titanite from the aplites indicate that the late magmatic evolution of the Moncha Tundra Massif proceeded at 2445 ± 1.7 Ma, and the youngest magmatic events in the massif related to the Svecofennian orogeny occurred at 1900 ± 9 Ma. The data obtained on the Sm-Nd and Rb-Sr isotopic systems and the distribution of trace elements and REE in rocks of the dike-vein complex of the massifs provide insight into the composition of the sources from which the parental magmas were derived. The high-Ti ferrodolerites were melted out of a deep-sitting plume source that contained an asthenospheric component. The ferrodolerites were derived from a mantle MORB-type source that contained a crustal component. The parental melts of the gabbro-dolerites were melted out of the lithospheric mantle depleted in incompatible elements after Archean crust-forming processes above an ascending mantle plume, with the participation of a crustal component. The gabbro-dolerites and the rocks of the layered complex of the Moncha Tundra Massif exhibit similar geochemical characteristics, which suggest that their parental melts could be derived from similar sources but with more clearly pronounced crustal contamination of the parental melts of the rocks of the massif itself. The geochemical traits of the gabbro-pegmatites are thought to be explained not only by the enrichment of the residual magmas in trace elements and a contribution of a crustal component but also by the uneven effect of sublithospheric mantle sources. The aplites were derived from a sialic crustal source.

A technique for developing a prototype of an industrial apparatus of the substance separation has been considered. This technique has been implemented in practice when choosing a prototype of the rectification column and the rubber degassing setup.

The NE Fennoscandian Shield comprises the Northern Belt in Finland and the Southern Belt in Karelia. They host mafic-ultramafic layered Cu-Ni-Cr and Pt-Pd-bearing intrusions. Precise U-Pb and Sm-Nd analyses indicate the 130-Ma evolution of these intrusions, with major events at 2.53, 2.50, 2.45, and 2.40 Ga. Barren phases were dated at 2.53 Ga for orthopyroxenites and olivine gabbro in the Fedorovo-Pansky massif. PGE-bearing phases of gabbronorites (Pechenga, Fedorovo-Pansky, Monchetundra massifs) and norites (Monchepluton) are 2.50 Ga old. Anorthosites of Mt. Generalskaya (Pechenga), the Fedorovo-Pansky, and Monchetundra massifs occurred at 2.45 Ga. This event produced layered PGE-bearing intrusions in Finland (Penikat, Kemi, Koitelainen) and mafic intrusions in Karelia. The Imandra lopolith dikes occurred at the final phase (2.40 Ga). Slightly negative &epsilon, Nd and ISr values (0.703&ndash, 0.704) suggest that intrusions originated from an enriched mantle reservoir. Low 3He/4He ratios in accessory minerals (ilmenite and magnetite) indicate an upper mantle source. Large-scale correlations link the Fennoscandian Shield with the Superior and Wyoming cratons.

A technique of calculating a multistage countercurrent liquid extraction in an apparatus with agitation of phases was proposed. Kinetic parameters of mass transfer was acquired based on concepts of pseudo-laminar boundary layer on the elements of the dispersed phase. An approximate method for calculating the installation was presented. The results of the calculation of the process according to a “stage by stage” scheme and approximate method are well consistent with each other.

A mathematical model of liquid extraction in stirred vessels is considered. The calculation results are compared with experimental data on extraction of various liquid mixtures.

is the A method is proposed for calculating the number of actual separation stages (trays) in columns from the given concentration of components in the original mixture and at the ends of the column (in the overhead and bottom products).

A method is considered for calculating the efficiency of trays and columns based on the hydrodynamic analogy of momentum and mass transport in a bubbling layer on the contact devices of mass transfer apparatuses.

A variational method is considered for determining the optimum parameters of apparatuses with stirring of a liquid phase using a mathematical model for the kinetics of dissolution or crystallization of small solid particles. The production rate of an apparatus that is limited by the flow of a substance through the boundary layer on the surface of solid particles is taken as an optimization criterion. The optimization problem for the degassing of rubber crumb in a stirred apparatus is solved.

A mathematical model is considered for the kinetics of dissolution and growth of solid particles by the diffusion mechanism in apparatuses with the stirring of a liquid phase. The mathematical model of the kinetics is based on the concept of the pseudolaminar boundary layer on the surface of a particle. The reliability of the developed mathematical model is verified by experimental data on rubber crumb degassing and silver halide crystallization in stirred apparatuses.

In the eastern part of the Baltic Shield, in the area of the Kola Peninsula, Karelia, and Finland, Early Proterozoic layered intrusives, regarded as a large� scale intrusive province associated with the mantle plume uplift (1, 2), are widespread. In this territory the Monchegorsk pluton is regarded as the most investi� gated. The pluton contains sulfide copper-nickel, chromite, and lowsulfide ore deposits with PGEbear� ing mineralization (3-6). In the root zone of the pluton, there were found dykes of unique lowpotassium tholeiites, formed in close temporal association with the pluton. However, the rock associations of the dykes and the pluton are different in composition and the nature of the mantle source. Study of these rocks is of great importance for understanding the nature of the mantle plume and the composition of the subcontinental lithosphere. In this study, the results of geological-geochemical study of these unique dykes are shown. The study area is located at the boundary between the Kola and Belomorskii blocks of the Archean con� tinental crust in the crossing point of the northwest� trending Pechenga-Varzuga rift belt and the subme� ridional transform fault. The transform fault is marked by a large gabbronorite-anorthosite Main Ridge mas� sive. The Monchetundra intrusive complex, a branch of the Main Ridge, has the shape of trough. The Monchegorsk nickelbearing pluton is located in the Archean granodiorites and gneisses of the Kola block. Two troughshaped branches of the pluton stretch in the southwesterly direction towards the Loypishnyun zone, the northwesttrending tectonic contact with the Monchetundra massive. The Loypishnyun zone is made of a series of steep parallel fracture bodies of dunites, harzburgites, orthopyroxenites, norites, and gabbro-norites with rare tectonic plates of Archean gneisses (Fig. 1). The Monchegorsk pluton bottom dipping towards the Loypishnyun zone and abundant presence of fracture bodies, composed of rocks close in composition to those of the layered series, made it possible to consider the zone as the root zone of the Monchegorsk pluton (4). The rocks of the pluton, located near the Loypishnyun zone are intruded by numerous dykes and veins of melanorites, gabbro- norites, microgabbro, granophyres, and microgran� ites. Lowpotassium tholeiites are found under the bot� tom of the Monchetundra gabbronorite-anortosite massif in the core sample, collected from the deep well M1 and on the slopes of the Pentlandite Gorge. They deposit in plagioschists and hyperstene hornstones, regarded as Archean gneisses reworked by mantle basite-ultrabasite melts (6). In gneisses, beyond the root zone of the pluton and within the pluton itself, dykes of such compositions have not been found. Thus, the dykes of lowpotassium tholeiites are spa� tially clearly connected with the root zone of the Monchegorsk pluton, but they formed probably ear� lier than the layered intrusive massifs. Lowpotassium tholeiites are referred to the dyke facies. The bodies of these tholeiites are of complex shape, and, sometimes, they are concordant with the folding of the country rocks. Sheetlike inclined bodies of up to 10 m in thickness are located in the wings of folds. Sometimes the stockwork bodies, formed by lowthick connected dykes occur. Lowpotassium tholeiites have textural-structural features not typical of dyke rocks. In tholeiite bodies, the chilled margins are absent. Instead of ophite struc� tures, typical for dyke rocks of such composition, the lowpotassium tholeiites are mainly characterized by a microgabbro structure. The segregations of darkcol� ored silicates have an amoeboid shape and aggregate structure. Two extreme types of tholeiites, i.e., olivine and pigeonite, are identified.