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Raman spectra of three natural carbonophosphates (sidorenkite, bonshtedtite, and bradleyite) with the general formula Na3MCO3PO4 (M is Mn, Fe, and Mg) were studied and compared. These spectra showed from 21 to 24 vibrational bands, of which the two most intense (964±5 and 1074±3 cm−1) correspond to the υ1(P–O) and υ1(C–O) modes. These two bands split into doublet peaks due to the occurrence of isomorphic impurities. It was found that the crystallographic orientation of the sample influences the intensity of most bands. Most bands assigned to the same vibrations showed a regular shift (the smallest in sidorenkite spectra, an intermediate in bonshtedtite, and the largest in bradleyite). We propose an algorithm that allows for diagnostics of carbonophosphates in inclusions by their Raman spectra, providing a reliable result even in the absence of energy-dispersive X-ray spectroscopy (EDX) data.

The Sallanlatva massif belongs to the group of Paleozoic alkaline-ultrabasic complexes wide spread in the Kola Region (the northwestern part of the Fennoscandian Shield). In the central part of this massif, the host ijolite and urtites contain calcite, ankerite, ankerite-dolomite and siderite carbonatites. The explosive processes that led to the formation of carbonatite breccias in the calcite and ankerite-dolomite carbonatites occurred in Sallanlatva massife in the last stages of the carbonatite magmatism. There are two types of explosive carbonatite breccias in the Sallanlatva massif: (1) glimmerite-calciocarbonatite breccias, and (2) siderite-dolomite breccias. Analysis of the mineral composition of fragments and matrix and the shape of fragments in breccias has shown that the first material to intrude into the host calcite and ankerite-dolomite carbonatites was calcite melt. After that, dolomite melt penetrated through the fracture zones, which resulted in the formation of siderite-dolomite breccias. The differences in the mineral composition of the breccia matrix suggest that the residual carbonatite melts originate from separate magma chambers. The chamber with calcite melt was located at great depth, and some captured glimmerite fragments were abraded during the melt upwelling. Silicate-dolomite melts lifted from a shallower depth; the captured fragments of siderite carbonatites retained their angular shape. Late hydrothermal processes yielded veins and caverns with Ba-Sr-P-S-Ti-REE mineralization in the breccias and host rocks.

Our previous Rb–Sr–O–C isotope data on the rare-earth carbonatites of the Petyayan-Vara area of the Vuoriyarvi massif (NW Russia) showed that these rocks were formed in two stages. The earliest burbankite-bearing carbonatites are sourced from Ba-Sr-REE-rich magnesiocarbonatite melt. The interaction of this melt with the host silicate rocks yielded high-Ti contact rocks, locally rich in apatite, HFSEs, and HREEs. An orthomagmatic S-rich fluid remobilized Ba, Sr, and REEs from burbankite-bearing carbonatites into fractures and breccia zones and deposited them as ancylite ores with strontianite and baryte. Sm-Nd isotopic data on bulk samples showed that very little time passed (by geological standards) between the intrusion of carbonatite melt and this early postmagmatic fluid REE process. The age estimates for ancylite ores (365 Ma) coincide with the age of igneous rocks. These findings are essential for understanding the reasons for the accumulation of such ores, selecting practical prospecting tools for exploration in the Vuoriyarvi massif, and searching for similar deposits.We studied the Sm-Nd system and the distribution of REEs in apatite using local methods to test this hypothesis. High-Ti carbonatites were formed simultaneously with burbankite-bearing carbonatites and underwent considered fluid processing. They contain two apatite generations: early Ap-1 (almost free of admixtures) and late Ap-2 (rich in REEs, Sr, and S). The chemical specificity of Ap-2 suggests that it was formed under the action of the fluid that remobilized the REEs. Chondrite-normalized REE spectra in Ap-2 are similar to the spectra of ancylite ores with LREECN>>HREECN (NdCN>SmCN), which confirms the above conclusion. The spectra of Ap-1 and Ap-2 are very different. The point is that Ap-2 is rich in HREEs, which results in LREECN≤HREECN (NdCNCN). Recent experimental works have shown that the interaction of carbonatite magma and Si-undersaturated silicate rocks occurring in the presence of alkalis leads to enrichment in HREEs. Thus, Ap-1 inherited the chemical components involved in the contact interaction of carbonatite melt and host rocks. Due to the contrasting differences in the NdCN/SmCN ratios for Ap-1 and Ap-2, the points of these phases in the 147Sm/144Nd–143Nd/144Nd diagram form two clusters, plotted far apart from each other along the 147Sm/144Nd axis. The errorchron drawn through these clusters gives an age of 350.7±16.7 Ma (3σ) at MSWD=2.3, which, within the error limits, coincides with the age estimates for both magmatism and ancylite ores. This estimate confirms the earlier assumption about the formation of ancylite ores during the late magmatic stage shortly after the magmatic event. Our results show that the in situ Sm-Nd analysis of apatite is an effective geochronological tool for assessing the age of REE ores for the case of interaction of carbonatite melt with Si-undersaturated silicate rocks and subsequent fluid processing.This research was funded by the Russian Science Foundation, grant № 19-77-10039.

This study develops a method to estimate the redistribution of elements during several associated metasomatic processes simultaneously involved in the formation of a geological complex. The method is based on classical mass balancing using isocon analysis. The proposed approach is applicable if geological prerequisites indicate that (a) the metasomatic rocks inherited some components (x, y, etc.) from one of the earlier rocks of the studied complex; (b) these components have been transported by a fluid; and (c) this saturated fluid has produced several varieties of metasomatic rocks rich in components x, y, etc. In the case of the specified background, the proposed method estimates the mass proportions between the source rock and the varieties of the resulting metasomatic rocks. We present the geological profile of the processes to which the proposed method is applicable, the mathematical model of the method, examples of the application and interpretation of the results, and geological criteria to verify the obtained model results. In brief,•This study introduces a method for calculating the mass proportions between the source rock and metasomatic rocks formed from the material remobilized from the source rock;•The paper considers the applicability limits of the method, exemplifies the interpretation of the results, and shows the methods for monitoring the correctness of these results., Graphical abstract Image, graphical abstract

Isotope signatures of noble gases incorporated into sulfides from alkaline-ultrabasic carbonatite complexes of the Devonian Kola Alkaline Province (Kola region, NW Russia) have not been studied previously. We investigated the isotope composition of helium and argon in pyrite and pyrrhotite from several carbonatite varieties of the Vuoriyarvi massif. The obtained data showed that the noble gas isotope systems are well preserved in sulfides from carbonatites. We found that sulfides from the Vuoriyarvi trapped both crustal (meteoric) waters and the modified mantle fluids. Fluids with a pronounced mantle He signature captured by pyrrhotite are isotopically homogeneous. In contrast, isotope signatures of He and Ar in pyrite evidence that this mineral was formed at a dynamic change of fluid sources. Evidence of fractionation of He and Ar due to degassing was also revealed. These results suggest that the isotopic signatures of noble gases in sulfides from carbonatites are promising as a tool for identifying the fluid phase associated with sulfide mineralization and paragenetic (i.e., REE-rich) minerals.

This paper presents an example of comparing geochemical and mineralogical data by means of the statistical analysis of the X-ray diffraction patterns and the chemical compositions of bulk samples. The proposed methodology was tested on samples of metasomatic rocks from two geologically different objects. Its application allows us to mathematically identify all the main, secondary and some accessory minerals, to qualitatively estimate the contents of these minerals, as well as to assess their effect on the distribution of all petrogenic and investigated trace elements in a short period of time at the earliest stages of the research. We found that the interpretation of the results is significantly influenced by the number of samples studied and the quality of diffractograms.

Along with some other Na-minerals, carbonophosphates indicate a high initial Na activity in carbonatite and kimberlite melts, which is beneficial for petrological reconstructions. Because carbonophosphates are capable of incorporating large-ion lithophile and rare earth elements (REEs) in their structure, they can participate in the transport of these elements. Moreover, due to the presence of both [PO4]3− and [CO3]2− groups in carbonophosphates, these mineral phases play an important role in the Earth's global carbon and phosphate cycles. With all these properties, carbonophosphates have long attracted the attention of geologists. Raman spectroscopy appears to be one of the most suitable tools for their diagnosis, since they commonly present in rocks as small inclusions in other mineral grains. Despite this profit, only a few publications contain Raman characteristics of either natural or synthetic carbonophosphates.We studied and compared Raman spectra of three natural carbonophosphate phases (sidorenkite, bonshtedtite, and bradleyite) with the general formula Na3MCO3PO4 (M = Mn, Fe, and Mg, correspondingly). These spectra showed from 21 to 24 vibrational bands, of which the two most intense (963±5 cm-1 и 1074±3 cm-1) correspond to the ν1(P–O) and ν1(C–O) modes. These two bands split due to the occurrence of isomorphic impurities. It was found that the crystallographic orientation of the sample influences the intensity of most bands. A natural increase in the Raman shift was observed for most bands assigned to the same vibrations (the smallest shift in the spectrum is characteristic of sidorenkite, an intermediate - of bonshtedtite, and the largest - of bradleyite).We propose the following algorithm for the diagnosis of carbonophosphates:Checking minerals for belonging to the group of carbonophosphates by the main bands and the characteristic profile of the spectrum; Testing the hypothesis that the mineral of question is bradleyite based on the analysis of the estimated shift of the main bands; Diagnosis of a mineral species by peaks located between the main bands; Validation of the diagnostics by considering the position of the bands at 185±9 cm-1, 208±7 cm-1, 255±5 cm-1, and 725±6 cm-1. The proposed algorithm allows one to perform Raman diagnostics of carbonophosphates in inclusions even in the absence of EPMA data. In the study of carbonatites, kimberlites, and other rocks, the diagnostics of the mineral species of the carbonophosphate group can be important in the petrological aspect.This research was funded by the Russian Science Foundation, grant number 19-77-10039.

Numerical comparison of mineralogical and geochemical data, which is required in a variety of geological applications, is a challenging task, especially when analyzing extensive sample collections. Herein, we apply factor analysis (FA) to a collection of 198 diffraction patterns of bulk rock samples from the Kontozero carbonatite complex. The mineralogical information hidden in the X-ray powder diffraction (XRPD) data is thereby squeezed down to a set of two dozen variables represented by factor scores (FS). The values of these FSs show a functional relationship with the contents of the minerals composing the rocks. Therefore, factor scores can be considered as a beneficial tool for rapid qualitative and semiquantitative analysis of the mineral composition of rocks. Supplementing principal component analysis (PCA) with FSs as independent variables characterizing the mineral content of rocks allows for the numerical comparison of mineralogical and geochemical data. By PCA, we reveal the main trends in the mineralogical and geochemical evolution of the investigated rocks of the Kontozero complex. Furthermore, the results are obtained in the very first stages of the research. This fact elucidates the potential use of the proposed technique in geological studies and mining.

The Vuoriyarvi Devonian alkaline&ndash, ultramafic complex (northwest Russia) contains magnesiocarbonatites with rare earth mineralization localized in the Petyayan-Vara area. High concentrations of rare earth elements are found in two types of these rocks: (a) ancylite-dominant magnesiocarbonatites with ancylite&ndash, baryte&ndash, strontianite&ndash, calcite&ndash, quartz (&plusmn, late Ca&ndash, Fe&ndash, Mg carbonates) ore assemblage, i.e., &ldquo, ancylite ores&rdquo, (b) breccias of magnesiocarbonatites with a quartz&ndash, bastn&auml, site matrix (&plusmn, Mg carbonates), i.e., &ldquo, site ores.&rdquo, We studied fluid inclusions in quartz and late-stage Ca&ndash, Mg carbonates from these ore assemblages. Fluid inclusion data show that ore-related mineralization was formed in several stages. We propose the following TX evolution scheme for ore-related processes: (1) the formation of ancylite ores began under the influence of highly concentrated (&gt, 50 wt.%) sulphate fluids (with thenardite and anhydrite predominant in the daughter phases of inclusions) at a temperature above300&ndash, 350 &deg, C, (2) the completion of the formation of ancylite ores and their auto-metasomatic alteration occurred under the influence of concentrated (40&ndash, 45 wt.%) carbonate fluids (shortite and synchysite&ndash, Ce in fluid inclusions) at a temperature above 250&ndash, 275 &deg, (3) bastn&auml, site ores deposited from low-concentrated (20&ndash, 30 wt.%) hydrocarbonate&ndash, chloride fluids (halite, nahcolite, and/or gaylussite in fluid inclusions) at a temperature of 190&ndash, 250 &deg, C or higher. Later hydrothermal mineralization was related to the low-concentration hydrocarbonate&ndash, chloride fluids (&lt, 15 wt.% NaCl-equ.) at 150&ndash, 200 &deg, C. The presented data show the specific features of the mineral and fluid evolution of ore-related late-stage hydrothermal rare earth element (REE) mineralization of the Vuoriyarvi alkaline&ndash, ultramafic complex.

The Petyayan-Vara area of the alkaline-ultramafic carbonatite complex Vuoriyarvi, located in Kola region (NW Russia; N 66°47’, E 30°05’), hosts abundant REE-Sr-Ba-rich magnesiocarbonatite veins. Magnesiocarbonatites containing burbankite are primary magmatic. These rocks underwent alterations during several magmatic-metasomatic events, which resulted in the formation of other varieties of carbonatites, including ancylite-dominant and bastnäsite-dominant magnesiocarbonatites (ores). We studied the Sr-Nd-C-O isotopic characteristics of both the most common varieties of carbonatites of the Petyayan-Vara area and calciocarbonatites (søvites) of its nearest surroundings. The isotopic composition of the least altered magnesiocarbonatites (εSr370=-13.9, εNd370=5.2, δ13CPDB=-3.8‰, δ18OSMOW=9.9‰) is close to that of søvites (εSr370=-13.5±0.1, εNd370=4.95±0.05, δ13CPDB=-3.85±0.25‰, δ18OSMOW=7.9±0.7‰). Analysis of other Petyayan-Vara carbonatites (including ancylite and bastnäsite ores) showed wide variations in signatures of all studied isotopic systematics. All altered carbonatites are enriched with crustal strontium (εSr370 of -12.8 to -2.0), and an increase in εSr370 is accompanied by an increase in the content of heavy isotopes of carbon (up to -1.0‰) and oxygen (up to 23.8‰). Most Petyayan-Vara carbonatites (including ancylite ores) have close values of εNd370=5.1±0.2. Isochron dating based on the figurative points of these rocks yielded an age of 365 Ma, indicating that the Sm-Nd radiogenic isotope system in the studied samples was unperturbed after carbonatites were crystallized. The similarity of the obtained εNd370 value with estimates of this parameter for different (both carbonate and silicate) rocks of the Vuoriyarvi complex indicates the isotopic homogeneity of the mantle source and its small contamination with the crustal material. Samples with a disturbed Sm-Nd system (εNd370 of -1.1 to 4.7) have petrographic signs of alterations during later processes (e.g., superimposed silicification, crystallization of the late strontianite, etc.). Bastnäsite ores also exhibit severely disturbed Sm-Nd system (εNd370=2.9). The change in εNd370 can be explained by either (1) an addition of crustal Nd or (2) chemical fractionation of Sm and Nd during events that occurred much later than the crystallization of Petyayan-Vara carbonatites. The obtained isotope data refine the sequence of the magmatic-metasomatic events that led to the formation of the Petyayan-Vara REE deposit, which we proposed earlier. They also clarify the contribution of the sources of elements and the scale of their redistribution at different formation stages of Petyayan-Vara carbonatites.This research was funded by the Russian Science Foundation, grant number 19-77-10039. Field work was supported by the Geological Institute KSC RAS, state order number 0226-2019-0053.

The objects of the study are apocarbonatitic titanium metasomatites ("titanium carbonatites") associated with the rare earth carbonatites of the Petyayan-Vara area of the Vuoriyarvi complex (the Kola region). In this paper, the following mechanism for the formation of these rocks has been substantiated based on the agreed results of mineralogical and geochemical studies. Prior to the onset of carbonatite genesis, a fluorine-enriched fluid phase originated in the lower horizons of the complex passed along the deep-permeating fracture system of several hundred meters length up to the level of the modern erosion surface. It transported Al, Fe2+, Mg, Ti, P into the pyroxenites and Si, Ca and Na out of them, as a result of which the pyroxenites were transformed into giant-grained phlogopite rocks – glimmerites. The most probable source of this fluid is alkaline aluminosilicate magma. Then carbonate melts intruded along the same fractures. In the course of carbonatite genesis, F-fluid caused a local migration of K, Al, Si, Fe, P, Ti, Nb, Ta, Zr, Hf and HREE out of glimmerites into igneous dolomite carbonatites, which led to the formation of apocarbonatitic titanium metasomatites. They represent several paragenetic associations superimposed on each other, the mineral composition and the formation sequence of which correspond to the metasomatic column zones directly observed within the contact "carbonatite – altered pyroxenite". The separation of HFSE and REE is controlled by the same metasomatic column: Ti, Nb and Ta were accumulated in titanium carbonatites, i. e. in associations of the frontal and intermediate zones, and Zr, Hf and HREE – in apatitized fields corresponding to the rear zone of the column. Accordingly, the fractionation of these elements occurred due to the "fluid – rock" interaction. Subsequently, the same long-lived fractures served as a channel for REE-Sr-Ba-S fluids, but the recrystallization caused by K-Al-Si-Ti-F-metasomatism made titanium carbonatites dense and fine-grained in texture, what, in most cases, "protected" these rocks from the influences of later processes.

The noble gas isotopic composition is studied in gas-liquid microinclusions from minerals of the corundum-bearing and host rocks of the Khitoostrov occurrence, North Karelia. It was established for the first time that fluid participating in the formation of rocks with anomalous oxygen isotopic composition is devoid of an atmospheric component, while helium and neon show significant fractionation relative to argon. The formation of rocks with extremely light oxygen isotope composition was related to the effect of endogenous fluid.

The results of complex petro-mineragraphic, Raman and isotope- geochemical study of three types of graphite- bearing rocks circulated at different distances from the alkaline granites: (1) kyanite schists of Bolshiye Keivy, sampled at a considerable distance from a contact with alkaline gran ites; (2) sillimanite schists, sampled close to the contact, and (3) silexites, located in the inner part of th e alkaline granite massif Western Keivy have been presented. Five morphogenetic types of graphite have been revealed in the rocks under consideration: fine- grained Gr-1, intergranular Gr-2, nest-shaped Gr-3, vein Gr- 4 and spherulitic Gr-5. Current study demonstrates that these five types of graphite distinctly vary not only i n morphology, but also in temperature of crystallization, as determined by RSCM-Raman geothermometer, and in carbon isotop e composition. The most likely source for the anomalous "light" graphite Gr-1 and Gr-2 [δ 13 C(PDB) = −43...−45 ‰] from kyanite schists is a water- methane fluid originating from sedimentary rocks with org anic compounds. The carbon of graphite Gr-5 of the silexites selected at the inner part of alkaline granite massif West ern Keivy, on the contrary, proved to be most "heavy" [δ 13 C(PDB) = −8 ‰], which indicates its origin from the lower crustal or mantle carbon dioxide fluid. Thus, carbon extracted into the rocks of Keivy structure from at least two contrasting isotope sources. Graphite Gr-3, that makes up the bulk of graphite of exocontact sil limanite schists, is also isotopically light, but not anomalously [δ 13 C(PDB) = −17...−28 ‰]. The crystallization temperature of the gi ven graphite (435−520 ºC), and its structural relationships with other minerals of th e rock evidence of its synmetamorphic origin. The presence of veinlets of isotopically heavy [δ 13 C(PDB) = −10 ‰...−11 ‰] high-temperature (570−670 ºC) graphite intersecting minerals of the metamorphic paragenesis (i ncluding Gr-3) indicates that the introduction of the granites occurred into the previously metamorphosed strat a and was accompanied by thermal and fluid influence on these strata.

The Vuoriyarvi Devonian carbonatite–ijolite–pyroxenite–olivinite complex comprises several carbonatite fields: Neske Vara, Tukhta-Vara, and Petyayan-Vara. The most common carbonatites in the Tukhta-Vara and Neske-Vara fields are calciocarbonatites, which host several P, Fe, Nb, and Ta deposits. This paper focuses on the Petyayan-Vara field, in which the primary magmatic carbonatites are magnesian. The least altered magnesiocarbonatites are composed of dolomite with burbankite and are rich in REE (up to 2.0 wt. %), Sr (up to 1.2 wt. %), and Ba (up to 0.8 wt. %). These carbonatites underwent several stages of metasomatism. Each metasomatic event produced a new rock type with specific mineralization. The introduction of K, Si, Al, Fe, Ti, and Nb by a F-rich fluid (or fluid-saturated melt) resulted in the formation of high-Ti magnesiocarbonatites and silicocarbonatites, composed of dolomite, microcline, Ti-rich phlogopite, and Fe–Ti oxides. Alteration by a phosphate–fluoride fluid caused the crystallization of apatite in the carbonatites. A sulfate-rich Ba–Sr–rare-earth elements (REE) fluid (probably brine-melt) promoted the massive precipitation of ancylite and baryte and, to a lesser extent, strontianite, bastnäsite, and synchysite. Varieties of carbonatite that contain the highest concentrations of REE are ancylite-dominant. The influence of sulfate-rich Ba-Sr-REE fluid on the apatite-bearing rocks resulted in the dissolution and reprecipitation of apatite in situ. The newly formed apatite generation is rich in HREE, Sr, and S. During late-stage transformations, breccias of magnesiocarbonatites with quartz-bastnäsite matrixes were formed. Simultaneously, strontianite, quartz, calcite, monazite, HREE-rich thorite, and Fe-hydroxides were deposited. Breccias with quartz-bastnäsite matrix are poorer in REE (up to 4.5 wt. % total REE) than the ancylite-dominant rocks (up to 11 wt. % total REE).

The Precambrian rocks of the Keivy Terrane reveal five types of carbonaceous matter (CM): Fine-grained, flaky, nest, vein, and spherulitic. These types differ in their distribution character, carbon isotope composition, and graphitization temperatures calculated by the Raman spectra of carbonaceous material (RSCM) geothermometry. Supracrustal rocks of the Keivy Terrane contain extremely isotopically light (&delta, 13CPDB = &ndash, 43 &plusmn, 3&permil, ) carbon. Presumably, its source was a methane&ndash, aqueous fluid. According to temperature calculations, this carbon matter and the host strata underwent at least two stages of metamorphism in the west of the Keivy Terrane and one stage in the east. The CM isotope signatures of several samples of kyanite schists (&delta, 33 &plusmn, 5&permil, ) are close to those of oils and oil source rocks, and they indicate an additional carbon reservoir. Thus, in the Keivy territory, an oil-and-gas bearing basin has existed. Heavy carbon (&delta, 13CPDB = &minus, 8 &plusmn, ) precipitated from an aqueous CO2-rich fluid is derived from either the lower crust or the mantle. This fluid probably migrated from the Keivy alkaline granites into the surrounding rocks previously enriched with &ldquo, methanogenic&rdquo, carbon.

We investigated carbonatites and aluminosilicate rocks from the Kontozero Devonian carbonatite paleovolcano complex (198 samples). Some specific features complicate the geological exploration of this object: a) the rocks of the Kontozero complex are predominantly volcanic and therefore exhibit small dimension of mineral grains and the diversity of their structural relationships; b) because breccias are common in many parts of the complex, the rocks are mostly inhomogeneous; c) Kontozero belongs to the alkaline-carbonatite formation, which is typically characterised by mineral diversity and the presence of rare minerals. The purpose of this study was to develop an algorithm for selecting from an extensive collection of rock material the most informative for mineralogical and geochemical studies samples. As a tool for this selection, we chose an original method of statistical comparison of XRD and XRF data using factor analysis (FA). This methodological approach enables mathematical identification of all major, minor, and several accessory minerals and a rough estimation of their contents (Fomina et al., 2019). We carried out the mineralogical interpretation of the factors according to the peak positions on the graphs of factor loadings and qualitative analysis of diffraction data of rock samples with maximum factor scores. For the studied rock collection, this approach allowed us to identify more than 20 rock-forming minerals based only on XRD data. Also, we found about ten mineral phases, the lines of which are low-intensity and/or overlap by more intense peaks of other minerals in the diffraction patterns. The mineralogical interpretation of the factors of these hidden minerals requires verification by an electron microscope investigation of the samples selected with FA. Based on the results of this study, we developed an algorithm that facilitates choosing rock samples that are most contrasted in mineral and chemical composition and contain the entire set of mineral phases characteristic of the rocks of the study object with minimal effort. In the case of our Kontozero rock collection, 30 representative samples were selected, which is about 15% of the initial sample set.

We applied factor analysis (FA) for statistical comparison of XRF and XRD data on 198 carbonatite and aluminosilicate rock samples of the Kontozero Devonian paleovolcano. This method helps to identify main, secondary, and some accessory minerals, as well as to estimate the approximate contents of these minerals and to assess their contribution on the distribution of major and trace elements (Fomina et al., 2019). With the view of control purposes, qualitative and semiquantitative analysis of diffraction data were performed. Several dozen factors quickly yielded to mineralogical interpretation. For the studied samples, a functional relationship was established between the calculated mineral content and the score of the factor (FS) corresponding to the mineral. Thus, the FS can serve as a handy tool for assessing the contents of minerals. Thereby we visualise the distribution of minerals in the space of the studied complex. We also found out which mineral phases are ubiquitous, and which present only in certain parts of the section or occur sporadically. These data allowed us to make a mineralogical interpretation of the results of FA, performed solely for the geochemical variables. The main trends in the mineralogical and geochemical evolution of carbonatite and aluminosilicate rocks of the Kontozero Devonian paleovolcano were thus determined and statistically substantiated. All these results were obtained in a short time at the earliest stages of the research. A “blind” statistical method guarantees the independence of the results on a priori hypothesis of the researcher. The time-consuming classical techniques (e.g., petrography, mineralogical studies, and quantitative analysis of diffraction data) verified the geological model described by statistics.

An X-ray installation was developed, the heart of which is a high-power microfocus X-ray tube. In addition to the tube, the installation includes a high-voltage power supply, an X-ray detector, a sample positioning system, components control sofware and image processing software. The testing of installation have been produced.

This paper reports the results of an investigation of metasomatic alterations in basement gneisses within the contact aureole of the Ozernaya Varaka alkaline ultrabasic massif. Based on mineralogical and geochemical data, the metasomatic rocks were classified, variations in major and trace elements were evaluated along a cross-section through the contact zone, the mobility of components during the metasomatic transformation of rocks was estimated, and the gain or loss of components was quantified. The obtained results provided insight into the trends of changes in mineral assemblages, the mechanisms of migration of fluid flows, and, most importantly, the scale of input or removal of major and a number of trace components at different stages of the evolution of the metasomatic system within the contact aureole and border zones. It was shown that a fluid phase was released directly from a magma chamber filled with alkaline ultrabasic melt, which is indicated by the high 3He/4He value (5.9 × 10−6) of the fluid, corresponding to 50% of the mantle component. It was shown that the release of a considerable amount of fluid phase related to the alkaline ultra-basic melt was not accompanied by a significant input of high field strength and rare earth elements. In contrast, the fluids of the subsequent carbonatite stage were enriched in volatile components (F, Cl, P, and S), which resulted in the migration of REE into the fenitized zones and removal of Ta, Zr, and Hf from it. The low 3He/4He value of this fluid suggests that its noble gases were contaminated by a crustal component, and solutions percolated along fracture systems and shatter zones from the root of the magmatic system. During the final postmagmatic stage, alkaline metasomatism was caused mainly by aqueous fluids and was accompanied by the removal of all rare earth elements and most of the high field strength elements (Nb, Ta, Zr, and Hf). A comparison of the fenitized zone of the Ozernaya Varaka complex with those of the Khibiny and Lovozero agpaitic syenite massifs showed that the metasomatic reworking of gneisses in the multiphase alkaline ultrabasic complex occurred in several stages and was accompanied by the input and removal of components, whereas the single-stage fenitization in the agpaitic syenite plutons involved minor amounts of heterogeneous water-fluoride fluids and resulted in extensive migration of rare earth and high-field strength elements in the contact zone.

The phase and structural states of titanium spheres loaded by spherical converging shock waves of various intensities were studied layer by layer by means of X-ray diffraction, optical, and transmission electron microscopy. It was established that defects of different types (twins, dislocations, and adiabatic shear bands) are produced during high-rate deformation occurring in materials under such method of pulsed loading. The amount and distribution of the defects depend on the loading intensity. The presence of the ω-phase is revealed only in the layers near the external surface of the titanium sphere after low-intensity loading.

X-ray diffraction, optical and transmission electron microscopy and measurement of microhardness were used to study zirconium, Zr–Ti and Zr–Nb alloys loaded by quasi-hydrostatic pressure and spherical converging shock waves of different intensity. It was revealed that the phase and structural states of the specimens depend on the loading type, the loading intensity, the niobium content, and the depth of the layer in the sphere. It has been established that there are two types of defects in the ω-phase structure: linear defects of displacements of [0001] atomic rows and stacking faults in the planes {2¯ 1¯ 10} irregularly distributed on a crystal.

A copper single crystal was deformed by spherical converging shock waves. The structure of the recovered specimen was studied by X-ray diffraction analysis (including back-reflection Laue technique), optical and transmission electron microscopy as well as by the measurement of microhardness along the radius in some radial directions. It is established that the high-rate plastic deformation of a copper single crystal under such loading proceeds mainly by both crystallographic and non-crystallographic slip.

X-ray diffraction, optical and transmission electron microscopy, and measurement of microhardness were used to study zirconium and Zr – Nb alloys loaded by spherical converging stress waves of different intensity. It is revealed that the phase and structural states of the specimens depend on the loading intensity, the niobium content and the depth of the layer in the sphere. The ω-phase (high pressure phase) is retained in a metastable state only after low-intensity loading, and the quantity of the ω-phase increases with increase in niobium content in the alloy. The ω-phase is not retained after high-intensity loading because of high remaining temperatures. It was established that various defects (deformation twins, dislocations, adiabatic shear bands, regions of unstable plastic flow and cracks) are produced during loading.