Geochemistry of volatiles in PGE ore of the Western Pana layered pluton in the Kola Peninsula

The distribution of volatiles in ore units of the Western Pana layered mafic pluton in the Kola province was studied with pyrolytic gas chromatography. In comparison with barren rocks, the rocks containing Pt-Pd mineralization are characterized by a much higher concentration of volatiles, especially H₂S, SO₃, and CH₄. With a drop in temperature, the redox potential of the fluid phase in the ore-magmatic system increased. PGE mineralization was largely formed at the postcumulus stage with participation of volatiles under variable redox conditions.     

Amphiboles of the Khibiny alkaline pluton, Kola Peninsula, Russia

The rocks of the Khibiny pluton contain 25 amphibole varieties, including edenite, fluoredenite, kaersutite, pargasite, ferropargasite, hastingsite, magnesiohastingsite, katophorite, ferrikatophorite, magnesiokatophorite, magnesioferrikatophorite, magnesioferrifluorkatophorite, ferrimagnesiotaramite, ferrorichterite, potassium ferrorichterite, richterite, potassium richterite, potassium fluorrichterite, arfvedsonite, potassium arfvedsonite, magnesioarfvedsonite, magnesioriebeckite, ferriferronyboite, ferrinyboite, and ferroeckermannite. The composition of rock-forming amphiboles changes symmetrically relative to the Central Ring of the pluton; i.e., amphiboles enriched in K, Ca, Mg, and Si are typical of foyaite near and within the Central Ring. The Fe and Mn contents in amphiboles increase in the direction from marginal part of the pluton to its center. Foyaite of the marginal zone contains ferroeckermannite, richterite, arfvedsonite, and ferrorichterite; edenite is typical of foyaite and hornfels of the Minor Arc. Between the Minor Arc and the Central Ring, foyaite contains ferroeckermannite, arfvedsonite, and richterite; amphiboles in rischorrite, foidolite and hornfels of the Central Ring are (potassium) arfvedsonite, (potassium) richterite, magnesiokatophorite, magnesioarfvedsonite, ferroeckermannite, and ferriferronyboite; amphiboles in foyaite within the Central Ring, in the central part of the pluton, are arfvedsonite, magnesioarfvedsonite, ferriferronyboite, katophorite, and richterite. It is suggested that such zoning formed due to the alteration of foyaite by a foidolite melt intruded into the Main (Central) Ring Fault.     

Rock-Forming feldspars of the Khibiny alkaline pluton,Kola Peninsula,Russia

This paper describes the structural-compositional zoning of the well-known Khibiny pluton in regard to rock-forming feldspars. The content of K-Na-feldspars increases inward and outward from the Main foidolite ring. The degree of coorientation of tabular K-Na-feldspar crystals sharply increases in the Main ring zone, and microcline-dominant foyaite turns into orthoclase-dominant foyaite. The composition of K-Na-feldspars in the center of the pluton and the Main ring zone is characterized by an enrichment in Al. This shift is compensated by a substitution of some K and Na with Ba (the Main ring zone) or by an addition of K and Na cations to the initially cation-deficient microcline (the central part of the pluton). Feldspars of volcanosedimentary rocks occurring as xenoliths in foyaite primarily corresponded to plagioclase An_15–40, but high-temperature fenitization and formation of hornfels in the Main ring zone gave rise to the crystallization of anorthoclase subsequently transformed into orthoclase and albite due to cooling and further fenitization. Such a zoning is the result of filling the Main ring fault zone within the homogeneous foyaite pluton with a foidolite melt, which provided the heating and potassium metasomatism of foyaite and xenoliths of volcanosedimentary rocks therein. The process eventually led to the transformation of foyaite into rischorrite-lyavochorrite, while xenoliths were transformed into aluminum hornfels with anorthoclase, annite, andalusite, topaz, and sekaninaite.     

Pyroxenes of the Khibiny alkaline pluton, Kola Peninsula

Seven pyroxene varieties were identified in nepheline syenites and foidolites of the Khibiny pluton: enstatite, ferrosilite, diopside, hedenbergite, augite, aegirine-augite, and aegirine. Enstatite and augite are typical of alkaline and ultramafic rocks of dike series. Ferrosilite was found in country quartzitic hornfels. Diopside is a rock-forming mineral in alkaline and ultramafic rocks, alkali gabbroids, hornfels in xenoliths of volcanic and sedimentary rocks and foyaite, melteigite-urtite that assimilate them, and certain hydrothermal pegmatite veins. Hedenbergite was noted in hornfels from xenoliths of volcanic and sedimentary rocks and in a hydrothermal pegmatite vein at Mount Eveslogchorr. Aegirine-augite is the predominant pyroxene in all types of nepheline syenites, phonolites and tinguaites, foidolites, alkaline and ultramafic rocks of dike series, fenitized wall rocks surrounding the pluton, and xenoliths of Devonian volcanic and sedimentary rocks. Aegirine is an abundant primary or, more often, secondary mineral in nepheline syenites, foidolites, and hydrothermal pegmatite veins. It occurs as separate crystals, outer zones of diopside and aegirine-augite crystals, and homoaxial pseudomorphs after Na-Ca amphiboles. Microprobe analyses of 265 pyroxenes samples allowed us to distinguish ten principal trends of isomorphic replacement and corresponding typomorphic features of pyroxenes. Compositional variations in clinopyroxenes along the sampled 35-km profile from the margin of the Khibiny pluton to its center confirm the symmetric zoning of the foyaite pluton relative to semicircular faults of the Minor Arc and the Main (Central) Ring marked by Devonian volcanic and sedimentary rocks, foidolites, and related metasomatic rocks (rischorrite, albitite, and aegirinite). Changes in the composition of pyroxenes are explained mainly by the redistribution of elements between coexisting minerals of foyaites in the process of their intense differentiation under the effect of foidolite melts that have intruded into the circular fault zones.     

PGE and Au minerals from the low-sulfide ore of the Pana Tundra Pluton,Kola Peninsula

The PGE minerals (PGM) in the low-sulfide ore of the Pana Tundra intrusion have been studied in the Northern and Southern reefs, Eastern Chuarvy and Churozero sites. Forty mineral species and five mineral phases of PGE and Au have been identified. The early magmatic sulfide-telluride-sulfarsenide assemblage and the late redeposited arsenide-telluride assemplage are distinguished on the basis of relationships between minerals and morphology of PGM. Toward the upper part of the intrusion and from the west eastward, the contribution of Pt- and Pd-sulfides to ore regularly decreases along with an increase in the amounts of Pt- and Pd-arsenides depending on the sequence of crystallization of host rocks and degree of their postmagmatic alteration. Microprobe analyses and variation in chemical compositions of PGM pertaining to the braggite-vysotskite, eoncheite-merenskyite, and kotulskite-sobolevskite isomorphic series are given.     

Nepheline-bearing alkali feldspar syenite (pulaskite) in the Khibina pluton,Kola Peninsula,NW Russia: petrological investigation

The geological position and probable origin of nepheline-bearing alkaline syenite (pulaskite) found within foyaite of the Khibina pluton, Kola Peninsula, Russia, are discussed. A large body of pulaskite (4.5 km²) was identified under the Quaternary deposits in the eastern part of the pluton as a result of gravimetric surveying and drilling. Genetic relations between pulaskite and the host foyaite were examined by whole-rock chemistry, including major and trace elements, the composition of the rock-forming clinopyroxenes and the diagram of phase equilibria in the system NaAlSiO₄–KAlSiO₄–SiO₂–H₂O. The results regarding mafic silicates show that pulaskite may constitute the less evolved member of a pulaskite-foyaite series, which suggests that it was formed by feldspar fractionation from an almost eutectic phonolitic melt, the parental one for both foyaite and pulaskite. The geochemical data, however, also enable us to assume the probability of additional petrogenetic mechanisms. The trace element abundance patterns may provide preliminary evidence for a process of crustal contamination of a mantle-derived phonolite magma. This process may have contributed to the genesis of the pulaskite.     

Spinel-group minerals in rocks of the Khibiny alkaline pluton,Kola Peninsula

Seven spinel-group minerals in various geological settings have been revealed in the rocks of the Khibiny pluton. Hercynite, gahnite, and vuorelainenite occur only in xenoliths of hornfels after volcanic and sedimentary rocks, whereas spinel and magnesiochromite occur in alkaline ultramafic rocks of dike series. Franklinite has been discovered in a low-temperature hydrothermal vein. Ubiquitous magnetite is abundant in foyaite, foidolites, alkaline ultrabasic rocks, and pegmatite and hydrothermal veins and may even be the main mineral in some foidolite varieties. The spinel-group minerals are characterized by various chemical compositions due to the fractionation of nepheline syenites resulting in formation of the Main ring of foidolites and apatite-nepheline ore. Like most other minerals found throughout the pluton, magnetite is characterized by variation in the chemical composition along the radial line from the contact with country Proterozoic volcanic rocks to the geometric center of the pluton. Toward the center, the total Ti and Mn contents in magnetite increase from 5–15 up to 40 at %.     

Corundum-group minerals in rocks of the Khibiny alkaline pluton,Kola Peninsula

Five minerals of the corundum group have been identified in the Khibiny pluton with certainty. Corundum proper and karelianite occur only in hornfels after volcanic and sedimentary rocks. Xenoliths of hornfels mark the ring faults that bound foidalite within the field of foyaite. Hematite occurs in hydrothermally altered nepheline syenite and crosscutting hydrothermal veins related to the ring faults. Minerals of the ilmenite-pyrophanite series are present in all rocks of the pluton, including veins. Accessory ilmenite in foyaite varies from the manganese variety and pyrophanite in the inner and outer parts of the pluton to manganese-free ilmenite in zone of the Main Ring Fault. In xenoliths of volcanic rocks and alkaline ultramafic rocks, ilmenite is enriched in magnesium. The zoning in distribution of the above-mentioned minerals and the character of variation in their compositions from margins of the pluton to its center are consistent with the petrochemical zoning formed as a result of foyaite alteration of near ring faults.     

PGM in chromite ore of the Sopcheozero deposit, Kola Peninsula

The Sopcheozero chromite deposit is hosted in dunite of the Monchegorsk layered intrusion as a sheetlike body of disseminated ore with a chromite grade varying from 20 to 60%. The total PGM content in the ore attains 0.5–0.8 g/t. The composition of host rocks varies from plagioclase peridotite to dunite, but PGM were found only in chromite-bearing dunite. PGM inclusions were detected in the interstices of chromite and olivine grains and within grains themselves. The data obtained confirm the known tendency toward variation in PGM composition with increasing sulfur and light PGE contents in the residual magmatic melt. The first particles of refractory Ir, Os, and Ru intermetallides appeared at the final stage of olivine crystallization, whereas laurite (Ru,Os,Ir)S₂ and pentlandite (Fe,Ni)₉S₈ were formed at the final stage of chromite crystallization, when the sulfur concentration in the residual melt became sufficient.     

Thorium mineralization in hyperalkaline pegmatites and hydrothermalites of the Lovozero pluton,Kola Peninsula

The Lovozero pluton (Kola Peninsula, Russia) is an unique object from the standpoint of the abundance, diversity, and originality of Th mineralization. In contrast to other igneous rocks and to such chemical elements as Ca, REE, U, and Na, Th in the hyperalkaline pegmatites and hydrothermalites of the Lovozero pluton commonly occurs as its own mineral phases. Umbozerite Na₃Sr₄Th(Mn,Zn,Fe,Mg)[Si₈O₂₄](OH) (7 samples), Ti-Th silicate Na_0–7Sr_0–1ThTi_1–2Si₈O_22–23(OH) · nH₂O (8 samples), Na-Th silicate (Na,K)₄Th₃[Si₈(O,OH)₂₄] · nH₂O (6 samples), thorite (2 samples), steenstrupine-(Ce)-thorosteenstrupine series minerals (5 samples), and Th phosphate (Th,Na,K,Ca,Mg,U,Sr,Ba)[(P,Si, Al)₁O₄] · nH₂O (1 sample) were investigated in this study. Ti-Th silicates and Th phosphate have been described for the first time. All of the above-mentioned minerals have been examined with electron microprobe, IR spectroscopy, powder diffraction, thermogravimetric and optical methods. High-Th minerals such as steenstrupine, umbozerite, Th phosphate, and Na-Th silicates crystallized mainly during the ussingite stage of the pegmatite-forming process. At the early hydrothermal high-alkaline stage, steenstrupine was replaced with REE and Th aggregates (belovite, vitusite, seidite, Na-Th silicates, Ti-Th silicates, etc.). Thorite, Ti-Th silicates, and minerals of the rhabdophane and monazite groups were formed at the late hydrothermal low-alkaline stage. Despite the metamict features of almost all samples, stoichiometric ratios of cations in umbozerites and Ti-Th silicates remain stable. Clear relationships have been revealed between umbozerites and Ti-Th silicates, on the one hand, and seidite-(Ce), a Ti-silicate that has a zeolite-like structure, on the other. This implies that, under certain conditions, these minerals may be regarded as potential suppliers of Th to the environment due to the leaching of Th from zeolite channels.     

俄罗斯科拉半岛铬云母玉的宝石学特征

在2010年,美国图桑的矿物宝石化石展销会上出现了一种新的玉石品种,其产自俄罗斯科拉半岛的铬云母玉。利用偏光显微镜、X射线粉末衍射仪、激光诱导离解光谱仪、红外光谱仪等测试方法对俄罗斯科拉半岛铬云母玉样品进行了分析与研究,初步确定其矿物组成、结构特征及宝石学性质。结果表明,该铬云母玉的主要矿物组成为铬云母、石英、长石,并含有少量的蓝晶石、十字石、高岭石、黄铁矿等;具有不等粒变晶结构和片麻状构造。与东陵石（即含铬云母的石英岩）的矿物组成和宝石学特征对比后,提出以铬云母的质量分数20%作为铬云母玉与东陵石的分类界限,其相应的宝石学和物理性质也可以对二者加以区分。     

Lake water geochemistry on the western Kola Peninsula,north-west Russia

Water samples were taken from 120 lakes spread over the western half of the Kola Peninsula, NW Russia. The samples were analysed for 37 elements, pH and electrical conductivity. Lake water chemistry appears in most cases to be dominated by a Ca/Na–HCO₃ signature, characteristic of natural carbonate/silicate weathering. Input of elements from marine derived salts and from the Ni industry (roasting plant at Zapoljarnij, smelter at Nikel and smelter/refinery at Monchegorsk) emissions are restricted to limited regions. Considering that 3 of the world's largest point source emitters of SO₂ are located within the area, the median lake water pH is surprisingly close to neutral (6.6, range 4.2–7.4). Indeed some of the apparently SO₄ contaminated lakes nearest to the smelters yield the highest pH values. Changes in climate and vegetation from north to south within the survey area probably have an influence on element concentrations and pH as observed in the lake waters. Proton displacement by sea salt cation input provides an explanation of low pH lakes in coastal areas.     

Postglacial emergence and the Tapes transgression, north-central Kola Peninsula, Russia

The history of postglacial emergence on the Murman coast, Kola Peninsula, is reconstructed based on twelve new radiocarbon ages from three marine sections and regional shoreline observations. Two pronounced shore levels are recognized below the Late Weichselian marine limit. The lower shoreline (11 -16 m a.s.l.) is associated with a transgression dated to 6200–6600 BP, correlative to the Tapes transgression on the Norwegian coastline. The upper shoreline (36–47 m a.s.l.) is not yet dated directly but probably correlates to the Main (Younger Dryas) shoreline. Strandline elevations descend eastward along the Murman coast. Observed emergence trends suggest the greatest regional Late Weichselian glacier load over the west-central Kola Peninsula rather than in the southern Barents Sea.     

Sulphide Segregation in Ferropicrites from the Pechenga Complex, Kola Peninsula, Russia

The Palaeoproterozoic Ni–Cu sulphide deposits of the PechengaComplex, Kola Peninsula, occur in the lower parts of ferropicriticintrusions emplaced into the phyllitic and tuffaceous sedimentaryunit of the Pilgujärvi Zone. The intrusive rocks are comagmaticwith extrusive ferropicrites of the overlying volcanic formation.Massive lavas and chilled margins from layered flows and intrusionscontain <3–7 ng/g Pd and Pt and <0·02–2·0ng/g Ir, Os and Ru with low Pd/Ir ratios of 5–11. Theabundances of platinum group elements (PGE) correlate with eachother and with chalcophile elements such as Cu and Ni, and indicatea compatible behaviour during crystallization of the parentalmagma. Compared with the PGE-depleted central zones of differentiatedflows (spinifex and clinopyroxene cumulate zones) the olivinecumulate zones at the base contain elevated PGE abundances upto 10 ng/g Pd and Pt. A similar pattern is displayed in intrusivebodies, such as the Kammikivi sill and the Pilgujärvi intrusion.The olivine cumulates at the base of these bodies contain massiveand disseminated Ni–Cu-sulphides with up to 2 µg/gPd and Pt, but the PGE concentrations in the overlying clinopyroxenitesand gabbroic rocks are in many cases below the detection limits.The metal distribution observed in samples closely representingliquid compositions suggests that the parental magma becamesulphide saturated during the emplacement and depleted in chalcophileand siderophile metals as a result of fractional segregationof sulphide liquids. Relative sulphide liquid–silicatemelt partition coefficients decrease in the order of Ir >Rh > Os > Ru > Pt = Pd > Cu. R-factors (silicate-sulphidemass ratio) are high and of the order of 10⁴–10⁵, andthey indicate the segregation of only small amounts of sulphideliquid in the parental ferropicritic magma. In differentiatedflows and intrusions the sulphide liquids segregated and accumulatedat the base of these bodies, but because of a low silicate–sulphidemass ratio the sulphide liquids had a low PGE tenor and Pt/Irand Cu/Ir ratios similar to the parental silicate melts. Duringcooling the sulphide liquid crystallized 40–50% of monosulphidesolid solution (mss) and the residual sulphide liquid becameenriched in Cu, Pt and Pd and depleted in Ir, Os and Ru. TheCu-rich sulphide liquid locally assimilated components of thesurrounding S-rich sediments as suggested by the radiogenicOs isotopic composition of some sulphide ores (     

Chromium mineralization in the Khibiny alkaline massif (Kola Peninsula,Russia)

This paper presents new data on chromium mineralization in a fenitized xenolith in Mt. Kaskasnyunchorr in the Khibiny alkaline massif (Kola Peninsula, Russia) and summarizes data on Cr mineralogy in the Khibiny Mountains. Protolith silicates that contained Cr³⁺ admixture are believed to be the source of this element in the fenite. Cr-bearing (maximum Cr₂O₃ concentrations, wt %, are in parentheses) aegirine (5.8), crichtonite-group minerals (2.1), muscovite (1.3), zirconolite (1.1), titanite (1.0), fluorine-magnesioarfvedsonite (0.8), biotite (0.8), ilmenite (0.6), and aenigmatite (0.6) occur in the fenite. The late-stage spinellides of the FeTi-chromite-CrTi-magnetite series, which are very poor in Mg and Al and which formed after Crrich aegirine and ilmenite, are the richest in Cr (up to 42% Ct₂O₃). Cr concentrations grew with time during the fenitization process. Unlike minerals in the Khibiny ultramafic rocks where Cr is associated with Mg, Al (it is isomorphic with Cr), and with Ca, chromium in the fenites is associated with Fe, Ti, and V (with which Cr³⁺ is isomorphic) and with Na in silicate minerals. Cr³⁺ Mobility of Cr³⁺ and the unique character of chromium mineralization in the examined fenites were caused by high alkalinity of the fluid.     

Typochemistry of rinkite and products of its alteration in the Khibiny Alkaline pluton,Kola Peninsula

The occurrence, morphology, and composition of rinkite are considered against the background of zoning in the Khibiny pluton. Accessory rinkite is mostly characteristic of foyaite in the outer part of pluton, occurs somewhat less frequently in foyaite and rischorrite in the central part of pluton, even more sparsely in foidolites and apatite–nepheline rocks, and sporadically in fenitized xenoliths of the Lovozero Formation. The largest, up to economic, accumulations of rinkite are related to the pegmatite and hydrothermal veins, which occur in nepheline syenite on both sides of the Main foidolite ring. The composition of rinkite varies throughout the pluton. The Ca, Na, and F contents in accessory rinkite and amorphous products of its alteration progressively increase from foyaite and fenitized basalt of the Lovozero Formation to foidolite, rischorrite, apatite–nepheline rocks, and pegmatite–hydrothermal veins.     

Elpasolite from hyperalkaline pegmatite of the Khibiny pluton, Kola Peninsula. Symmetry of elpasolite

Elpasolite, K₂NaAlF₆, has been found for the first time in a pegmatite related to peralkaline foid syenite at Mt. Koashva, Khibiny alkaline pluton, Kola Peninsula, Russia, as pale pink octahedral crystals up to 2 mm in size within cavities in the natrolite core of pegmatite in association with amicite, sodalite, aegirine, pectolite, catapleiite, sitinakite, lemmleinite-K, and vinogradovite. The chemical composition determined with an electron microprobe is as follows, wt %: 31.53 K; 9.22 Na; 11.20 Al; 47.21 F; total is 99.16. The empirical formula is K_1.96Na_0.98Al_1.01F_6.05. The infrared spectrum is given. The crystal structure has been refined to R = 0.030, space group Fm $ \bar 3 Elpasolite, K₂NaAlF₆, has been found for the first time in a pegmatite related to peralkaline foid syenite at Mt. Koashva, Khibiny alkaline pluton, Kola Peninsula, Russia, as pale pink octahedral crystals up to 2 mm in size within cavities in the natrolite core of pegmatite in association with amicite, sodalite, aegirine, pectolite, catapleiite, sitinakite, lemmleinite-K, and vinogradovite. The chemical composition determined with an electron microprobe is as follows, wt %: 31.53 K; 9.22 Na; 11.20 Al; 47.21 F; total is 99.16. The empirical formula is K_1.96Na_0.98Al_1.01F_6.05. The infrared spectrum is given. The crystal structure has been refined to R = 0.030, space group Fm m, a = 8.092 ?. The result of a special X-ray powder diffraction study confirmed the suggestion made by Morss (1974) that reflections violating space group Fm m in some published X-ray powder patterns of natural elpasolite are Kβ-lines. Original Russian Text ? I.V. Pekov, N.V. Chukanov, N.N. Kononkova, N.V. Zubkova, M.Kh. Rabadanov, D.Yu. Pushcharovsky, 2007, published in Zapiski Rossiiskogo Mineralogicheskogo Obshchestva, 2007, No. 6, pp. 76–84.     

Anthropogenic noble-metal enrichment of topsoil in the Monchegorsk area, Kola Peninsula, northwest Russia

Eight catchments, an area of 15 to 35 km², have been studied within an ecogeochemical mapping programme in the western Kola Peninsula and contiguous parts of Finland and Norway. Three catchments, one northeast of Zapolyarniy (1) and two, 5 and 25 km south of Monchegorsk (2 and 4) show high levels of deposition of heavy metals, especially nickel (Ni) and copper (Cu), related to the metallurgical industry in these cities. Twenty-five topsoil samples, from sites evenly distributed over catchment 2, have mean contents of Ni and Cu 1 to 2 orders of magnitude higher than both C-horizon samples from the same sites and topsoil samples from catchment 4, providing strong evidence for the anthropogenic origin of the heavy metals. The same samples show geometric mean total contents for the noble metals analysed of: 1.4 μg/kg rhodium (Rh), 49.6 μg/kg platinum (Pt), 187.6 μg/kg palladium (Pd) and 9.5 μg/kg gold (Au). The pattern of concentration of the noble metals mirrors that found in published averages for ore from the Talnakh mineralizations in the Noril'sk province, though 1–2 orders of magnitude lower. This also clearly shows that the noble-metal contents of the topsoil are anthropogenic, and suggests that they emanate from the plants in Monchegorsk at an early stage in treatment of the ore, probably as a minor component of Ni-Cu rich particles. The noble-metal geochemistry of the topsoil in the other catchments also reflects the nature of the ore being processed at the plants nearby.     

Loparite-(Ce) from the Khibiny Alkaline Pluton,Kola Peninsula,Russia

Data on the occurrence, morphology, anatomy, composition, and formation conditions of loparite-(Ce) in the Khibiny alkaline pluton are given. Loparite-(Ce), (Na,Ce,Sr)(Ce,Th)(Ti,Nb)2O6, resulted from metasomatic alteration and assimilation of metamorphic host rocks at the contact with foyaite as well as foyaite on the contact with foidolite. This alteration was the highest in pegmatite, and albitite developed there. A decrease in temperature resulted in enrichment of the perovskite and tausonite endmembers in loparite-(Ce) owing to a decrease in the loparite and lueshite endmembers. La and Ce sharply predominate among rare earth elements in the composition of loparite-(Ce).     

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 ?_Hf 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.