Lovozero Massifs Research Articles

SEISMICITY of the RUSSIAN PART of EAST EUROPEAN PLATFORM and ADJACENT TERRITORIES in 2018–2019

Seismic observations by 48 stationary seismic stations, including twelve temporary seismic stations located in the area of Novovoronezh and Kursk nuclear power plants, were carried out on the Russian territory of the East European Platform. A feature of seismicity in 2018–2019 is a unique Kandalaksha earthquake of November 5, 2019 with ML=3.8 in the Belomorsky region. Its focal mechanism was represented by a normal fault. For the first time, a noticeable earthquake with МL=3.4 was recorded on September 5, 2019 at the Pashninskoye and Beregovoye fields in the Timan-Pechora oil and gas province. It was felt in Neftepechorsk working settlement with an intensity of up to 4 MSK-64. As before, weak natural seismicity was recorded on the Baltic Shield: in Karelia, in areas bordering Finland, near the Kandalaksha Bay, near the Khibiny and Lovozero massifs on the Kola Peninsula, on the Voronezh crystalline massif territory, especially in the zone of its junction with the DnieperDonetsk trough.

SEISMICITY of the RUSSIAN PART of EAST EUROPEAN PLATFORM and ADJACENT TERRITORIES in 2016–2017

Seismic observations by 46 stationary seismic stations, including seven temporary seismic stations located in the area of Novovoronezh and Kursk nuclear power plants, and by two arrays were carried out on the Russian territory of the East European Platform. A feature of seismicity in 2016–2017 is a manifestation of swarms of weak earthquakes in the northwest in the Leningrad region and the adjacent territory of Finland, as well as earthquakes on the Ukrainian Shield with Мs(est.)=3.8 in Krivoy Rog, where mass explosions are carried out in mines, but earthquakes of moderate magnitude МL=2.6–3.9 also occur (2007, 2013). Weak earthquakes in the peripheral parts (in the southwest, west and northwest) and in zones associated with paleorift structures: in the northeast – with the Kirov-Kazhim and Central Russian aulacogenes continue to be recorded. Weaker natural seismicity with ML≤2.5 was recorded in Karelia and the regions bordering Finland, near the Kandalaksha Bay, near the Khibiny and Lovozero massifs on the Kola Peninsula and in the territory of the Voronezh crystalline massif.

Iron in Nepheline: Crystal Chemical Features and Petrological Applications

Nepheline is a nominally anhydrous aluminosilicate that typically contains an impurity of ferric iron replacing aluminum in tetrahedral sites. However, previous researchers noted the constant presence of ferrous iron in the chemical composition of nepheline from the rocks of the Khibiny and Lovozero massifs (Kola Peninsula, Russia). We have carried out microprobe, spectroscopic, chemical and crystal chemical studies of nepheline from the Lovozero massif. We have established the presence of molecular water in nepheline, and also that the incorporation of ferrous iron into nepheline crystal structure is associated with the simultaneous increasing of the coordination number from four to five (or six) due to the inclusion of the ‘additional’ water molecules that form point [FeO4(H2O)n]-defects (where n = 1, 2) in the tetrahedral framework. The nepheline iron content is closely related to the presence of small needle-like aegirine inclusions. The total iron content in nepheline saturated with aegirine needles is approximately an order of magnitude lower than in nepheline free from aegirine inclusions. Most likely the aegirine inclusions in nepheline are formed as a result of the decomposition of the nepheline–“iron nepheline” solid solution. We propose that this process is triggered by the oxidation of ferrous iron in the crystal structure of nepheline.

Morphotectonics, Seismicity, and Exogenous Processes of the Kola Peninsula

Abstract—The purpose of this study is to determine a morphologically pronounced fault–block structure identified with the neotectonic stage and compare it with sites with manifested exogenous processes, as well as modern and historical paleoseismicity in order to establish faults activated in the postglacial time. Based on the analysis of space images (Landsat-ETM+) and a digital elevation model (GTOPO-30), the territory of the Kola Peninsula and the adjacent part of North Karelia is subjected to morphostructural interpretation with identifying morpholineaments and an elementary block structure. It is shown by the analyzing the directions and extent of elementary, single (simple), and complex (echeloned, parallel conjugated, and imbricated) linear structures and their zones that both linear (fault) and areal (block) structures are characterized by a predominance of a single system of northwestern and northeastern differences with a clear dominance of the former and unimodal distribution of the extent of faults and the area of blocks, depending on their number. This indicates a single (recent) stage in the formation of the morphotectonic appearance of the territory and no discrete hierarchy of the morphostructures. The degree of fragmentation of the territory at different depths is calculated depending on the number and extent of morpholineaments. It is determined that morpholineaments have a high degree of inheritance from Archean–Proterozoic structures (≈50%). Elementary morphotectonic blocks are grouped into composite blocks bounded by linear zones of great extent (100–600 km) having individual physiognomic features determined by fault patterns, which indicates the nature of the neotectonic dynamics and the degree of inheritance or reformation of the structural plan. The localization of manifestations of exogenous processes, epicenters of paleo-, historical, and modern earthquakes is determined on the basis of the analysis of topographic maps scaled at 1:100,000, catalogs of historical and paleoearthquakes, and the consolidated literature (including the data obtained by the authors of this study) on paleoseismic deformations. A geoinformation base is compiled, which is used to simulate the spatial distribution of endo- and exogenous signs of tectonic activity and compare it with the neotectonic fault–block structure. The spatial similarity of endogenous and exogenous activation zones and their confinement to faults, defined as activated in the postglacial time, are revealed. It is revealed that the following elements are most active in the postglacial–Holocene. First, flank elements on the Kola Peninsula along the Barents Sea coast, the Kandalaksha Bay shores, and the Gorlo Strait of the White Sea. Second, the central (nodal) part with the Khibiny and Lovozero massifs. Third, submeridional (transverse) secant structures separating the eastern part of the peninsula from the western part (Khibiny–Kola and Khibiny–Niva). The spatial parameters of the activated zones indicate a range of earthquake magnitudes M ≈ 6.5–7.5 generated by these structures both in the postglacial period and in the Neopleistocene as a whole.

Receiver-Function Velocity Structure of the Lithosphere beneath the Khibiny and Lovozero Massifs, Northeastern Baltic Shield

Receiver-Function Velocity Structure of the Lithosphere beneath the Khibiny and Lovozero Massifs, Northeastern Baltic Shield

Sulfur isotope signatures of sulfides from the Khibina and Lovozero massifs (Kola Alkaline Province, Fennoscandian Shield)

The sulfur isotope geochemistry of the Khibina and Lovozero agpaitic massifs provides an opportunity to understand the role of plume-lithosphere interaction processes responsible for the Paleozoic alkaline igneous activity in the north-eastern part of the Fennoscandian Shield. The stable sulfur isotope δS analysis using triple collector isotope ratio mass spectrometer (IRMS) has been carried out on the pentlandite, chalcopyrite and pyrite from nepheline syenites. The δS values for pentlandite from Khibina rocks range from +0.69 to +2.06 ‰ relative to the Vienna Canyon Diablo Troillite standard (VCDT), and the pyrite has significantly higher δS values up to +4.92 ‰ VCDT. The pentlandite from the Lovozero samples has value +1.48 ‰ VCDT, δS values of chalcopyrite is +2.85 ‰ VCDT. The maximum positive δS values are obtained for Lovozero pyrite, which vary from +5.41 to +6.30 ‰ VCDT. Comparison of sulfur-geochemical features of Khibina and Lovozero nepheline syenite with δS data for the carbonatites from the Khibina, Sallanlatvi, Seblyavr, Vuoriyarvi, Salmagora and Kovdor massifs show later carbonatite formation relatively to associated alkaline rocks. Geochemical sulfur isotope δS investigations emphasizes that parental magmas of the Khibina and Lovozero alkaline massifs were derived from a metasomatized subcontinental lithospheric mantle (SCLM). We suggest that high-δS signature on the SCLM (δS of +1 to +6 ‰ VCDT) can be explained by subduction of the high-δS Archaean crust.

Occurrence Forms, Composition, Distribution, Origin and Potential Hazard of Natural Hydrogen–Hydrocarbon Gases in Ore Deposits of the Khibiny and Lovozero Massifs: A Review

The Khibiny and Lovozero massifs—the world’s largest alkaline massifs—contain deposits with unique reserves of phosphorus and rare metals, respectively. The reduced gas content in the rocks and, especially, the ore deposits of these massifs is unusually high for igneous complexes, thus representing both geochemical and practical interests. There are three morphological types (or occurrence forms) of the gas phase in these deposits: occluded (predominantly in vacuoles of micro-inclusions in minerals), diffusely dispersed, and free. All three morphological types have the same qualitative chemical gas composition. Methane is the main component, and molecular hydrogen (which sometimes dominates) and ethane are the subordinate constituents. Heavier methane homologs (up to and including pentanes), alkenes, helium, and rarely carbon oxide and dioxide are present in minor or trace amounts. All three morphological types of gases are irregularly distributed in space to various degrees. Free gases also show a release intensity that varies in time. The majority of researchers recognize that the origin of these gases is abiogenic and mostly related to the formation of the massifs and deposits. However, the relative time and mechanism of their generation are still debated. Emissions of combustible and explosive hydrogen–hydrocarbon gases pose hazards during the underground mining of ore deposits. Therefore, the distinctive features of gas-bearing capacity are an essential part of the mining and geological characterization of such deposits because they provide a basis for establishing and implementing special measures of the gas regime during mining operations.

U-Pb SHRIMP-II ages of titanite and timing constraints on apatite-nepheline mineralization in the Khibiny and Lovozero alkaline massifs (Kola Peninsula)

Results of this study of titanite samples collected from silicate rocks and apatite-nepheline-(sphene) ores from Paleozoic polyphase alkaline nepheline syenite complexes of the Khibiny and Lovozero massifs revealed the possibility of their in-situ U-Pb dating using sensitive high-resolution ion microprobe SHRIMP-II with an accuracy of 1.0-1.5%, which is comparable with that of U-Pb zircon analysis. Employing different approaches to age determination of the formation of the U-Pb system of titanites, the combined isochrons and mixing lines were plotted from the data obtained from the differentiated complex samples (121 analyses of five Khibiny samples and 52 analyses of one Lovozero sample) and apatite-nepheline ores (120 analyses of five Khibiny samples and 88 analyses of three Lovozero samples). They indicate synchronous crystallization of titanite in silicate rocks throughout the complexes: 374.1 ± 3.7 Ma for the Khibiny massif and 380.9 ± 4.5 Ma for the Lovozero massif, and attest to the later formation of phosphate-rare-metal ores: 371.0 ± 4.2 and 361.4 ± 3.2 Ma, respectively. The relatively delayed ore mineralization specific to the Lovozero massif can be accounted for the significantly lower volumes of magmatic melt and ore fluid involved, different thermal conditions, and the pattern of the investigated mineralization. As such, the obtained U-Pb data from titanite make it possible to limit significantly the time interval (most likely, not exceeding 15-20 Ma) comprising the evolution and activity of the ore-magmatic system of major agpaitic complexes, which is probably associated with plume magmatism.

Evolution of pyroxene in peralkaline magmatic system: An example of an agpaitic syenite dyke complex and the Niva intrusion, Kola Peninsula

The paper presents pioneering data on the composition of pyroxenes and the distribution of trace elements in this mineral in small geological bodies that were formed by single magma injections and their subsequent rapid crystallization: the Niva intrusion and an agpaitic syenite dyke. The pyroxene is highly alkaline and shows continuous compositional trends with an increase in the aegirine concentration. The Ti concentrations of the pyroxene are much higher than in pyroxenes in agpaitic syenites in other alkaline complexes. In spite of the fact that the pyroxene is hosted in small bodies, the evolution of these pyroxenes was similar to that of pyroxenes in the Lovozero and Khibina alkaline massifs.

U-Pb geochronology and Sr-Nd isotopic systematics of minerals from the ultrabasic-alkaline massifs of the Kola province

This paper reports the results of U-Pb geochronological and Sr-Nd isotopic geochemical investigations (LA-ICP-MS) for perovskite, apatite, titanite, and calcite from the ultrabasic-alkaline rocks of the Paleozoic Kola alkaline province of the Fennoscandian Shield. Based on the obtained data, two main stages were distinguished in the history of Paleozoic intrusions in this province: (1) formation of ultrabasic-alkaline series of the Kovdor, Afrikanda, Turiy Mys, Ozernaya Varaka, Lesnaya Varaka, and other massifs, as well as the ultrabasic-alkaline series of the Khibiny and Lovozero massifs (385–375 Ma) and (2) formation of agpaitic syenites in the Khibiny and Lovozero calderas (375–360 Ma) and related apatite-nepheline deposits (370 Ma). The Sr-Nd isotopic geochemical investigations of perovskite, apatite, and titanite, which are the main hosts for the rare earth elements and Sr in ultrabasic-alkaline rocks, showed that variations in the Sr and Nd isotopic characteristics of these rocks are related to a large extent to crustal contamination during the ascent of their parental melts toward the surface and crystallization in magma chambers. As a result, the Sr and Nd isotopic characteristics of late minerals (apatite and titanite) do not reflect the initial Sr and Nd isotopic ratios of the primary magma. Initial ratios in the primary mantle melts are most closely approximated by the isotopic characteristics of phases crystallizing during early stages (e.g., perovskite).

A Pb isotope investigation of the Lovozero Agpaitic Nepheline Syenite, Kola Peninsula, Russia

For the first time Pb isotope composition was established in Lovozero rocks and raremetal ores, which is important for identifying their sources. The world’s largest layered intrusion of agpaitic nepheline syenite-the Lovozero alkaline massif—is located near the center of the Kola Peninsula in Russia. This superlarge complex plutonic body hosts the economically important loparite and eudiallyte deposits [1]. These deposits contain immense resources of REE, Nb, Ta, Zr, and constitute a world class mineral district. The Lovozero massif belongs to the Kola ultramafic alkaline and carbonatitic province (KACP) of Devonian age. Previous bulk rock studies have shown that the initial Sr and Nd isotope ratios of Lovozero rocks plot in the depleted mantle quadrant of Sr-Nd diagrams [2]. More recently, Hf isotope data obtained by Kogarko et al. (3) confirm that the Lovozero and Khibina massifs with ɛHf between 6 and 8 are derived predominantly from a depleted mantle source. It was shown that Sr, Nd, and Hf abundances are significantly elevated in the Kola alkaline rocks, and thus their isotopic compositions are relatively insensitive to minor contamination by the overlying crustal rocks. By contrast, Pb in the KACP rocks is a much more sensitive indicator of a crustal component. In this paper we investigate the lead isotopic signature of all resentative types of Lovozero rocks (Table 1) in order to further characterize their mantle sources. The Lovozero massif consists of four intrusive phases. Rocks of phase I (mostly nepheline syenites) comprise about 5% of the total volume, phase II (urtites, foyaite, lujavrites) forms the main portion of the massif comprising 77% in volume, and phase III (eudialyte lujavrites) contributes about 18%. Country rocks are represented by Devonian effusive rocks and Archean gneisses.

Formation of solid bituminous matter in pegmatites: Constraints from experimentally formed organic matter on microporous silicate minerals

The formation of solid bituminous matter (SBM) on surfaces of microporous silicates was experimentally studied at pressure and temperature conditions typical of late-stage magmatic and hydrothermal processes. Aliquots of microporous silicate minerals (zorite and kuzmenkoite-Mn, Lovozero Alkaline Massif, Kola Peninsula, Russia) were exposed to solid or liquid organic carbon sources (natural brown coal and liquid 1-hexene for synthesis purposes) in a 0.1M NaCl-solution for 7 days, at constant pressure (50MPa), and at three individual temperatures (200, 275, and 300°C). No thermal decomposition of the solid organic sources happened at 200°C and only a thin film of brown coal derivatives on the silicates’ surfaces and no formation of SBM were observed at 275°C and 300°C. But solid bituminous matter on the surfaces of both microporous silicates were detected in experiments with liquid 1-hexene as organic carbon source and at temperatures of 275°C and 300°C with a more pronounced formation of SBM at 300°C compared to 275°C. The aromatic and aliphatic hydrocarbons, as well as alcoholic compounds of the experimentally produced SBM are similar, if not even partly identical, with natural SBM occurrences of the Khibiny and Lovozero Massifs, Kola Peninsula, Russia, and from the Viitaniemi granitic pegmatite, Finland, as shown by FT-IR and 1H NMR spectroscopy. This strengthens the hypothesis of formation of natural solid bituminous matter by catalytic reactions between microporous Ti-, Nb- and Zr-silicates and hydrocarbons at postmagmatic hydrothermal conditions.

Bitumen biomarkers in the Mid-Proterozoic Ilímaussaq intrusion, Southwest Greenland – A challenge to the mantle gas theory

GC and GC/MS/MS analysis on rock extracts has shown that the bitumen in the peralkaline Ilímaussaq intrusion, previously assumed to be abiogenic, is biotic in origin. A biotic origin is in accordance with previously published stable carbon isotopic data on bituminous matter in the rocks. The biomarker distribution in the bitumen, including the less common bicadinanes, resembles that of oil seeps on the central West Greenland coast 2200 km farther north, whose source rocks and migration history are relatively well established. We use a recent re-construction of the subsidence and later exhumation of the West Greenland coastal region during the Mesozoic-Cenozoic ( Japsen et al., 2006a, b) to anticipate that hydrocarbons migrated from deeper parts of the basin offshore west of Greenland. The rocks of Ilímaussaq were probably more deeply invaded than the surrounding granites due to their higher proportion of corroded minerals, which may explain why bitumen has not been observed elsewhere in the area. Hydrocarbon gases (C1–C5) present in fluid inclusions were also analysed, after having been released by treatment with hydrochloric acid that resulted in an almost complete disintegration of the Ilímaussaq intrusion rocks. The acid extraction method proved generally more efficient than the crushing procedure applied by others, but gave similar results for the chemical composition of the gas (CH 4: 88–97%) and isotopic ratios (δ 13 C CH 4 : −1.6 to −5.0‰; δ 13 C C 2 H 6 : −9.2 to −12.5‰), with the exception of hydrocarbons hosted in quartz, which showed significantly lower isotopic values for methane ( Graser et al., 2008). Previous researchers have suggested an abiotic origin for these hydrocarbon gases, but we suggest a biotic origin for the majority of them, not just those in quartz, assuming that the isotopic ratio of the constituents have changed due to loss of gas by diffusion. The assumption of gas loss via diffusion is supported by published studies on micro-fissures in minerals typical of the Ilímaussaq and field investigations showing diffusive loss of gas from the peralkaline Khibina and Lovozero massifs on the Kola Peninsula, Russia, which are, in many respects of mineralogy and hydrocarbon content, similar to the Ilímaussaq intrusion. Both the hydrocarbon gases and bitumen in the Khibina and Lovozero massifs have been cited as prime examples of a deep mantle source, although the carbon isotopic ratio of the bitumen clearly pointed to an organic origin. The trends in carbon isotopic ratio of methane released with time from freshly exposed rocks also supports our hypothesis of 13C enrichment of the methane remaining within the rock. Thus, there is good evidence that the hydrocarbons in the Kola alkaline massifs are mostly biotic in origin, in which case the probability of finding economic hydrocarbon accumulations from a deep mantle source seems exceedingly small.

Contact interaction of agpaitic magmas with basement gneisses: An example of the Khibina and Lovozero Massifs

Data on processes that occurred at contacts of large agpaitic syenite intrusions and basement gneisses obtained by the authors by studying and sampling profiles across the contacts and involve the composition of minerals, analysis of mineral assemblages, isotopic dating of the processes, and analysis of the behavior of major, volatile, and trace elements in rocks near the contact. The contact zones of the massifs were determined to consist of products of contact interaction during the early and late magmatic stages and provide a record of successive stages of a continuous process of gneiss transformations, starting with the filling of the magmatic reservoir with melt and ending with late- and postmagmatic processes related to the development of a system of alkaline veins and pegmatite bodies in the gneisses. Early alkaline metasomatic processes in the Khibina Massif were local, controlled by diffusion, and were induced by the immediate thermal and chemical effect of alkaline melts on the gneisses. In the Lovozero Massif, metasomatism was related predominantly to the development of postmagmatic veins at 359 ± 5 Ma, was controlled by infiltration, and proceeded immediately after the consolidation of the main intrusive series. The metasomatic transformations during the early and late magmatic stages under the effect of agpaitic melts on gneisses predetermined different closure conditions and, correspondingly, different behaviors of the Rb-Sr and Sm-Nd isotopic systems during the contact processes: while the interaction of agpaitic melts with gneisses has modified the (87Sr/86Sr)(T = 370 Ma) ratio via the enrichment of radiogenic Sr in the host Archean rocks, the Sm-Nd isotopic characteristics of the syenites in the inner contact zone and veins preserved their mantle values, which corresponded to the average ones for rocks in the central parts of the intrusion. Experimental data, model simulations, and natural observations testify that Nb, Ta, Zr, Hf, and REE were mobile in the contact interaction zone with agpaitic melts. With regard for data on the fluid regime of the agpaitic melts and the concentrations of volatile components in the contact zones, we believe that the main role in the transfer of REE and HFSE during contact metasomatism could be played by their ligands with F−, Cl−, and SO42−.

Plume-related mantle source of super-large rare metal deposits from the Lovozero and Khibina massifs on the Kola Peninsula, Eastern part of Baltic Shield: Sr, Nd and Hf isotope systematics

The two world’s largest complexes of highly alkaline nepheline syenites and related rare metal loparite and eudialyte deposits, the Khibina and Lovozero massifs, occur in the central part of the Kola Peninsula. We measured for the first time in situ the trace element concentrations and the Sr, Nd and Hf isotope ratios by LA-ICP-MS (laser ablation inductively coupled plasma mass spectrometer) in loparite, eudialyte an in some other pegmatitic minerals. The results are in aggreement with the whole rock Sr and Nd isotope which suggests the formation of these superlarge rare metal deposits in a magmatic closed system. The initial Hf, Sr, Nd isotope ratios are similar to the isotopic signatures of OIB indicating depleted mantle as a source. This leads to the suggestion that the origin of these gigantic alkaline intrusions is connected to a deep seated mantle source—possibly to a lower mantle plume. The required combination of a depleted mantle and high rare metal enrichment in the source can be explained by the input of incompatible elements by metasomatising melts/fluids into the zones of alkaline magma generation shortly before the partial melting event (to avoid ingrowth of radiogenic isotopes). The minerals belovite and pyrochlore from the pegmatites are abnormally high in 87Sr /86Sr ratios. This may be explained by closed system isotope evolution as a result of a significant increase in Rb/Sr during the evolution of the peralkaline magma.

Diffusively disseminated hydrogen-hydrocarbon gases in rocks of nepheline syenite complexes

The composition and concentrations of gases disseminated in rocks (and moving through them mainly via diffusion) and characteristics of their release from these rocks were studied in the Khibina and Lovozero massifs in the Kola Peninsula. Similar to fluid inclusions occluded in vacuoles in minerals and unlike local “jet” gas exhalations, diffusively disseminated gases (DDG) ubiquitously occur in the massifs in variable concentrations. Along with predominant methane and hydrogen, subordinate amounts of methane homologues, and helium, DDG most commonly contain carbon dioxide (in higher concentrations than gases in other modes of their occurrence). One of the most important factors controlling the spontaneous release character of diffusively disseminated gases and their proportions of individual components is the geomechanical state of the rocks. It is proved that the distributions of all modes of gas occurrence in the rocks are generally not interrelated, and hence, it is senseless to utilize the contents of occluded and forcibly extracted gases to predict hazardous gas emissions in mines during the development of mineral deposits related to nepheline syenite complexes.

New data on the deep structure of the Khibiny and Lovozero massifs, Kola Peninsula

New data on the deep structure of the Khibiny and Lovozero massifs, Kola Peninsula

Hydrocarbons and other volatile components in alkaline rocks from the Ukrainian shield and Kola Peninsula

Gas chromatography and other analytical techniques (EMR, PMR, and IR spectroscopy) were used to examine volatile components (CH4, C2-C3, CO2, CO, H2, H2O, and others) in alkaline rocks and minerals from the Ukrainian Shield (eight massifs and dikes of grorudites) and from the Khibina and Lovozero massifs in the Baltic Shield. The alkaline rocks from the Ukrainian Shield are mostly of Proterozoic (1.7–2.1 Ga) age. The alkaline rocks from the Kola Peninsula were confirmed to be rich in methane (21 ± 14 μl/g on average) and other hydrocarbons, whereas the analogous rocks from the Ukrainian Shield are poor in methane (2.1 ± 1.6 μl/g on average at a maximum of 14 μl/g). The latter rocks are richer in CO2, which is one of the major volatile components of alkaline rocks, including agpaitic nepheline syenites from the Kola Peninsula. The rocks from the Ukrainian Shield often have elevated contents of nitrogen (up to 20 μl/g). The reasons for the differences in the composition of volatile components of rocks from the Kola Peninsula and Ukrainian Shield are as follows: the agpaitic crystallization trends of large massifs in the Kola Peninsula and much less clearly pronounced agpaitic trends in the small massifs in the Ukrainian Shield, the affiliation of these rocks with different complexes, the deeper erosion levels of the Ukrainian alkaline massifs, different ages of these rocks, etc.

On the problem of the formation and geochemical role of bituminous matter in pegmatites of the Khibiny and Lovozero alkaline massifs, Kola Peninsula, Russia

Solid bituminous matter (SBM) typically occurs in the late hydrothermal assemblages of pegmatites of the Khibiny and Lovozero massifs, being confined to a microporous framework Ti-, Nb-, and Zr-silicates, which are sorbents of small molecules and efficient catalysts of the polymerization, reforming, and selective oxidation of organic matter. Bituminous matter from the pegmatites of the Lovozero Massif typically have elevated contents of aliphatic hydrocarbons, sulfur, and sodium, but are depleted in oxygen and trace elements. SBM from the pegmatites of the Khibiny Massif are depleted in sulfur and enriched in oxygen-bearing derivatives of polycyclic aromatic hydrocarbons. Being complexing agents for Th, REE, Ba, Sr, and Ca, they play a key role in the transfer and accumulation of Th and in the accumulation of alkali earth and rare earth elements during the hydrothermal stage of mineral formation. Oxidized SBM bearing rare and alkali earth elements are complex microheterogenous systems, which contain mineral (Th silicates, calcite, etc.), metalorganic (with REE, Ca, Sr, Ba), and predominantly organic phases formed by the exsolution of initial metalorganic material with decreasing temperature.

On the geological age of Lovozero and other alkaline massifs of the Kola Peninsula

On the geological age of Lovozero and other alkaline massifs of the Kola Peninsula