Olivine Melanephelinites Research Articles

Melilite-olivine neрhelinites of Mt. Tabaat (Makhtesh Ramon, Israel): Geological, petrographic and geochemical characteristics and conditions of genesis

Research subject. The melilite-olivine nephelinite subvolcanic body Tabaat, which includes melilite rocks found for the first time on the territory of Levant.Materials and methods. The chemical composition of minerals (about 400 analyzes) was determined out on a CAMECA SX-100 microanalyzer equipped with five wave spectrometers with crystal analyzers TAP, LPET and LLIF. The elemental composition was measured at an accelerating voltage of 15 kV, an electron beam current of 40 nA. The oxygen concentration was calculated from the condition of stoichiometric composition of silicate minerals and chromite. In addition, the results of earlier studies of minerals (150 analyses) and data on melt inclusions were used.Results. The Tabaat subvolcanic body, which is part of the Early Cretaceous olivine-basalt-basanite-nephelinite association Makhtesh Ramona (Negev, Israel), has a complex concentrically-zonal structure, with olivine melanephelinites in the peripheral zone, melilite-olivine melanephelinites in the central and connecting zones normative and, less often, melilite-containing melanephelinites. Prismatic separation is widely manifested in the rocks. The fold-like bending and concave-curved edges of the prisms are a reflection of the plastic state of the cooling body and its ability to compress and accommodate a high fluid pressure, which develops during the formation of melilite nephelinites.Conclusion. All mineral diversity of rocks of the Mt. Tabaat is a derivative of a single portion of magmatic melt under conditions of its adiabatic cooling at the place of stabilization. A special role in the course of crystallization of the massif belongs to minerals with a high water content – analcime, zeolites, iddingsites, bowlingites and saponite-celadonites, which indicate the deuteric stage of its development. The study of melt inclusions in olivine and clinopyroxene showed the continuity of their composition with the composition of host melilite nephelinites and the importance of incongruent melting during the formation of melilite, which is a product of the reaction of nepheline with olivine or clinopyroxene.

Petrology of lamprophyre dykes in the Kola Alkaline Carbonatite Province (N Europe)

The study reports petrography, bulk major and trace element compositions of lamprophyric Devonian dykes in three areas of the Kola Alkaline Carbonatite Province (N Europe). Dykes in one of these areas, Kandalaksha, are not associated with a massif, while dykes in Kandaguba and Turij Mys occur adjacent (< 5 km) to coeval central multiphase ultramafic alkaline‑carbonatitic massifs. Kandalaksha dyke series consists of aillikites - phlogopite carbonatites and monchiquites. Kandaguba dykes range from monchiquites to nephelinites and phonolites; Turij Mys dykes represent alnöites, monchiquites, foidites, turjaites and carbonatites. Some dykes show extreme mineralogical and textural heterogeneity and layering we ascribe to fluid separation and crystal cumulation. Melt evolution of the dykes was modelled with Rhyolite-MELTS and compared with the observed order and products of the crystallization. Our results suggest that the studied rocks were related by fractional crystallization and liquid immiscibility. Primitive melts of aillikites or olivine melanephelinites initially evolved at P = 1.5–0.8 GPa without a SiO2 increase due to abundant clinopyroxene crystallization controlled by the CO2-rich fluid. At 1–1.1 GPa the Turij Mys melts separated immiscible carbonatite melt, which subsequently exsolved late carbonate-rich fluids extremely rich in trace elements. Kandaguba and Turij Mys melts continued to fractionate at lower pressures in the presence of hydrous fluid to the more evolved nephelinite and phonolite melts. The studied dykes highlight the critical role of the parent magma chamber in crystal fractionation and magma diversification. The Kandalaksha dykes may represent a carbonatite – ultramafic lamprophyre association, which fractionated at 45–20 km in narrow dykes on ascent to the surface and could not get more evolved than monchiquite. In contrast, connections of Kandaguba and Turij Mys dykes to their massif magma chambers ensured the sufficient time for fractionation, ascent and a polybaric evolution. This longevity generated more evolved rock types with the higher alkalinity and an immiscible separation of carbonatites.

Geochemical indicators of the evolution of the ultrabasic-alkaline series of Paleozoic massifs of the Fennoscandian shield

Rareearth element distribution in the rocks and minerals of the olivinite-clinopyroxenite- melilitolite-melteigite-ijolite-nepheline syenite series was analyzed to study the evolution trends of the alkaline-ultrabasic series of the Kola province. The contents of REE and some other trace elements were determined in olivine, melilite, clinopyroxene, nepheline, apatite, perovskite, titanite, and magnetite. It was established that distribution of most elements in the rocks of the Kovdor, Afrikanda, Vuoriyarvi, and other massifs differ from that in the Khibiny ultrabasic-alkaline series, being controlled by perovskite crystalliza� tion. Primary olivine-melanephelinite melts of the minor ultrabasic-alkaline massifs are characterized by the early crystallization of perovskite, the main REE-Nb-Ta-Th-U depository. Precipitation of perovskite simultaneously with olivine and clinopyroxene results in the depletion of residual magma in rareearth ele� ments and formation of lowREEand HFSE ijolite and nepheline syenite derivatives. In contrast, the for� mation of the Khibiny ultrabasic-alkaline series was complicated by mixing of olivine melanephelinite magma with small batches of phonolitic melt. This led to a change in crystallization order of REEbearing titanates and Tisilicates and accumulation of the most incompatible elements in the late batches of the melt. As a result, the Khibiny ijolites have the highest REE contents, which are accommodated by highREE apa� tite and titanite.

Trace elements in minerals as indicators of the evolution of alkaline ultrabasic dike series: LA-ICP-MS data for the magmatic provinces of northeastern Fennoscandia and Germany

In this paper we report the results of the analysis of rare earth (REE), large-ion lithophile (LILE), and high field strength (HFSE) elements in minerals from the alkaline lamprophyre dikes of the Kola region and the Kaiserstuhl province by the local method of laser ablation inductively coupled plasma mass spectrometry. The contents of Y, Li, Rb, Ba, Th, U, Ta, Nb, Sr, Hf, Zr, Pb, Be, Sc, V, Cr, Ni, Co, Cu, Zn, Ga, La, Ce, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, and Lu were measured in olivine, melilite, clinopyroxene, amphibole, phlogopite, nepheline, apatite, perovskite, and the host fine-grained groundmass. The obtained data on trace element partitioning among the mineral phases of the alkaline ultrabasic rocks of the dike series indicate that the main mineral hosts for the HFSEs and REEs in alkaline picrites, olivine melanephelinites, and melilitites are perovskite and apatite comprising more than 90% of these elements. Among major rock-forming minerals, melilite, clinopyroxene, and highly magnesian amphibole make a significant contribution to the balance of REEs during the evolution of melanephelinite melts. The partition coefficients of Ni, Co, Cu, Zn, Sc, V, Cr, Ga, Y, Li, Rb, Ba, Th, U, Ta, Nb, Sr, Hf, Zr, Pb, Be, and all of the REEs were calculated for olivine, clinopyroxene, amphibole, phlogopite, nepheline, perovskite, and apatite on the basis of mineral/groundmass ratios. Variations in the composition of complex zoned clinopyroxene phenocrysts reflect the conditions of polybaric crystallization of melanephelinite melt, which began when the magmas arrived at the base of the lower crust and continued during the whole period of their ascent to the surface. The formation of green cores in clinopyroxene is an indicator of mixing between primary melanephelinite melts and phonolite magmas under upper mantle conditions. The estimation of the composition of primary melts for the rocks of the alkaline ultrabasic series of the Kola province indicated a single primary magma for the whole series. This magma produced pyroxene cumulates and complementary melilitolites, foidolites, and nepheline syenites.

Asthenospheric signature in fertile spinel lherzolites from the Viliga Volcanic Field in NE Russia

Abstract Mantle xenolith bearing olivine melanephelinites from the Okhotsk sector of the Okhotsk–Chukotka Volcanic Belt (OCVB), northeastern Russia, occur as small isolated volcanoes emplaced within massive late Early to Late Cretaceous subduction-related calc-alkaline rocks. The xenoliths are typical medium- to fine‐grained anhydrous mainly spinel lherzolites that are strongly to weakly foliated with intensive to minor recrystallization to equigranular texture. The primitive mantle normalized whole-rock REE have flat patterns or patterns with slightly elevated light REE (LREE) ((La/Yb) N =0.48–1.38). The REE in clinopyroxenes have systematically decreasing normalized abundances from Sm to La, implying that the LREE enrichments in the whole‐rock REE patterns are attributed to circulation of minor intergranular fluids or melts. Equilibration temperatures and pressures calculated for the Viliga samples are in the range of 1050–1160 °C and 15–21 kbar, respectively. Ca diffusion rates in olivine reveal a rapid transport to the surface (2–6 days) of these peridotites. Model calculations have shown that the fertile lherzolites can be produced by 2–9% batch melting, whereas the depleted peridotites require 15% batch melting of a primitive source. The cessation of the interaction between the palaeo-Pacific plate and the NE Russian margin at c . 87 Ma apparently caused a ‘piecemeal’ collapse of the former followed by intrusion and ascent of olivine melanephelinitic magma, which entrained xenoliths from the asthenospheric mantle of the subducted plate during the Pliocene through the generated window(s). Moreover, clinopyroxenes that have low 87 Sr/ 86 Sr and high 143 Nd/ 144 Nd and plot in and above the mid-ocean ridge basalt (MORB) field are consistent with an upwelling asthenospheric mantle through the window(s) created by the ‘piecemeal’ collapse of the palaeo-Pacific plate.

ROCHAS VULCÂNICAS ALCALINAS DA FORMAÇÃO QUIXABA DE FERNANDO DE NORONHA, PE: QUÍMICA MINERAL E LITOGEOQUÍMICA

The lava flows of the Quixaba Formation (4,2 - 1,5 Ma) are olivine melanephelinites (OLM), olivine melilite melanephelinites (MEM) and pyroxene melanephelinites (PIM), with levels of pyroclastic rocks and relatively thin basanite flows (BAS). Thick BAS sequences occur in Baía do Sancho and in the São José, Cuscuz and de Fora islets. Olivine compositions (m# = 85 - 75) in melanephelinites and most BAS match those of clinopyroxenes (mg# 86 -74), indicating equilibrium crystallization. The São José and Cuscuz basantitic olivine (mg# 72 - 70) and clinopyroxene (mg# = 79 -74) compositions are similar and denote more differentiated rocks. In MEM, the amount (&gt; 10% to &lt;2%) and composition of melilites are variable. The melilite-rich rocks have abundant olivine, with melilites poorer in MgO and richer in Al 2 O 3 . Ba, Ti- (and F) rich phlogopite and biotite are late minerals with typical chemical features in each rock type. The Si0 2 content is an indicator of the chemical differences between melanephelinites: -MEM: 37-39 wt.%; OLM: 38-40 wt.%; PIM: 40-43 wt.%-. BAS have 45-46 wt.% Si02. The increase in silica is accompanied by increase in Al 2 O 3 and decrease in MgO, Ti0 2 , Fe 2 O 3total , CaO, MnO, Cs, Y and REE. Trace element ratios show important discrepancies among the melanephelinite types: MEM e OLM: La/Nb = 0.6-0.7; Zr/Nb = 2.7-3.2; PIM: La/Nb = 0.7-1.0; Zr/Nb = 2.6-5.7. The amount of trace elements and the incompatible element ratios are variable in BAS. The data presented in this paper denote the existence of crystal fractionation processes, for instance between PIM and the thin BAS flows in the lava sequence. On the other hand, the high amount of incompatible elements in the melanephelinites and the differences in element ratios in the several rock types, point to an origin from distinct parental magmas, derived from either different mantle sources, or different degrees of partial melting of the same source.

ROCHAS VULCÂNICAS ALCALINAS DA FORMAÇÃO QUIXABA DE FERNANDO DE NORONHA, PE: QUÍMICA MINERAL E LITOGEOQUÍMICA

The lava flows of the Quixaba Formation (4,2 - 1,5 Ma) are olivine melanephelinites (OLM), olivine melilite melanephelinites (MEM) and pyroxene melanephelinites (PIM), with levels of pyroclastic rocks and relatively thin basanite flows (BAS). Thick BAS sequences occur in Baia do Sancho and in the Sao Jose, Cuscuz and de Fora islets. Olivine compositions (m# = 85 - 75) in melanephelinites and most BAS match those of clinopyroxenes (mg# 86 -74), indicating equilibrium crystallization. The Sao Jose and Cuscuz basantitic olivine (mg# 72 - 70) and clinopyroxene (mg# = 79 -74) compositions are similar and denote more differentiated rocks. In MEM, the amount (> 10% to <2%) and composition of melilites are variable. The melilite-rich rocks have abundant olivine, with melilites poorer in MgO and richer in Al 2 O 3 . Ba, Ti- (and F) rich phlogopite and biotite are late minerals with typical chemical features in each rock type. The Si0 2 content is an indicator of the chemical differences between melanephelinites: -MEM: 37-39 wt.%; OLM: 38-40 wt.%; PIM: 40-43 wt.%-. BAS have 45-46 wt.% Si02. The increase in silica is accompanied by increase in Al 2 O 3 and decrease in MgO, Ti0 2 , Fe 2 O 3total , CaO, MnO, Cs, Y and REE. Trace element ratios show important discrepancies among the melanephelinite types: MEM e OLM: La/Nb = 0.6-0.7; Zr/Nb = 2.7-3.2; PIM: La/Nb = 0.7-1.0; Zr/Nb = 2.6-5.7. The amount of trace elements and the incompatible element ratios are variable in BAS. The data presented in this paper denote the existence of crystal fractionation processes, for instance between PIM and the thin BAS flows in the lava sequence. On the other hand, the high amount of incompatible elements in the melanephelinites and the differences in element ratios in the several rock types, point to an origin from distinct parental magmas, derived from either different mantle sources, or different degrees of partial melting of the same source.

Magmatic Evolution of the Melilitite-Carbonatite-Nephelinite Dyke Series of the Turiy Peninsula (Kandalaksha Bay, White Sea, Russia)

Major and trace element data are presented from a suite of INTRODUCTION melilitite–carbonatite–nephelinite dykes, the youngest of three dykes During the last decade, several volumes have outlined swarms in the Turiy peninsula, Russia. The most primitive dykes the progress that has been made in carbonatite research consist of olivine melanephelinites and olivine–melilite mela(Bell, 1989; Egorov, 1991; Bell & Keller, 1995). However, nephelinites that contain high-pressure phases (Cr-diopside and lowcertain problems still remain unresolved. For example, Ca forsteritic olivine). These dykes approximate the composition of what are the petrogenetic relationships between intrusive the parental melt, which probably originated by low-degree partial and volcanic carbonatites? Do carbonatite melts represent melting of metasomatized peridotite. Least-squares mass-balance primary mantle liquids or secondary melts? Are carcalculations and geochemical modelling indicate that differentiation bonatites the products of liquid immiscibility from alkaline was controlled by fractional crystallization involving olivine, clinosilicate melts or do they represent the end products of pyroxene, melilite, Ti-magnetite, apatite, and perovskite. The calfractional crystallization? If carbonatite melts are derived culated modal proportions of the cumulate minerals correspond to by differentiation processes, what were the parental silsome of the rocks seen in alkaline ultramafic plutons elsewhere in icate melts? the Kola peninsula. Calciocarbonatite dykes, with quenched primary Some of these questions can be investigated from the magmatic fabrics, were probably continuously separated by liquid study of the melilitite–carbonatite–nephelinite dyke series immiscibility from an evolved carbonated nepheline melilitite parent. associated with the Turiy complex, Kola (Fig. 1), one of The conjugate silicate liquid to the carbonatitic melt is a melilite several alkaline ultramafic and carbonatite complexes of nephelinite. The distribution of LREE, Zr, Hf, Ta, W, Pb, and the Kola peninsula and northern Karelia (Kukharenko Cu between the carbonatite and melilite nephelinite is in reasonable et al., 1965). One of the main geological features of the agreement with experimental data on element partitioning between Turiy peninsula is the evidence for three distinct episodes alkaline silicate and carbonate melts. of alkaline magmatism. In this paper, the mineralogy and geochemistry of the melilitite–carbonatite–nephelinite dyke series, the youngest of the three groups of dykes at Turiy, are discussed and a quantitative petrogenetic model is proposed for its origin.

Magmatic Evolution of the Melilitite-Carbonatite-Nephelinite Dyke Series of the Turiy Peninsula (Kandalaksha Bay, White Sea, Russia)

Major and trace element data are presented from a suite of melilitite–carbonatite–nephelinite dykes, the youngest of three dykes swarms in the Turiy peninsula, Russia. The most primitive dykes consist of olivine melanephelinites and olivine–melilite melanephelinites that contain high-pressure phases (Cr-diopside and low-Ca forsteritic olivine). These dykes approximate the composition of the parental melt, which probably originated by low-degree partial melting of metasomatized peridotite. Least-squares mass-balance calculations and geochemical modelling indicate that differentiation was controlled by fractional crystallization involving olivine, clinopyroxene, melilite, Ti-magnetite, apatite, and perovskite. The calculated modal proportions of the cumulate minerals correspond to some of the rocks seen in alkaline ultramafic plutons elsewhere in the Kola peninsula. Calciocarbonatite dykes, with quenched primary magmatic fabrics, were probably continuously separated by liquid immiscibility from an evolved carbonated nepheline melilitite parent. The conjugate silicate liquid to the carbonatitic melt is a melilite nephelinite. The distribution of LREE, Zr, Hf, Ta, W, Pb, and Cu between the carbonatite and melilite nephelinite is in reasonable agreement with experimental data on element partitioning between alkaline silicate and carbonate melts.

Geochemistry and petrogenesis of the tertiary alkaline volcanic suite of the Labe tectonovolcanic zone, Czech Republic

The Tertiary alkaline, nepheline-normative olivine melanephelinite-basanite-phonolite suite in the Labe tectono-volcanic zone, Czech Republic, displays mineralogical and geochemical features indicative of the presence of products of more than one fractionation series and of more than one parental magma. The Mg- and Ni-rich olivine melanephelinites (ankaratrites), which contain disintegrated lherzolite xenoliths, represent low degree (c. 4%) partial melts of a highly enriched mande source. Many of the abundant basanitic rocks also represent primary or near-primary basaltic melts subject to a small but variable degree Fof olivine fractionation. Other basanites with lower mg-numbers and Mg and Ni contents had a crystallization history involving hornblende and phlogopite.

Primitive olivine melanephelinite dykes from the Orkney Islands, Scotland

AbstractTwo suites of Permian dykes in the Orkney Islands consist of a predominantly ENE trending camptonite suite and a mainly N-to NE-trending suite formerly referred to as monchiquitic. Some of the silica-poor and more magnesium dykes in the latter suite can be more precisely defined as olivine melanephelinites. Within the parochial context of the British Isles, such compositions appear to be unique. The magmas are deduced to have been primitive, small-scale (? &lt; 0.2%) partial melt products of the asthenospheric mantle that have experienced relatively little modification in transit through the lithosphere.

Nephelinitic and Basanitic Rocks

Basanites (which mineralogically should be characterized by an abundance of plagioclase and only a little feldspathoid) and nephelinitic rocks (which normally lack modal plagioclase but should contain nepheline) are not easily distinguished in the field, and both are commonly confused with basalts. Since the mineralogical distinction sometimes cannot be applied, as in the case when no modal felsic minerals are apparent in the groundmass, a chemical distinction between nephelinitic and basanitic rocks becomes desirable. The best solution is provided by the use of the CIPW norm with basanites recognized as having > 5% normative ab and < 20% normative ne, melanephelinites as having < 5% normative ab and < 20% normative ne, and nephelinites as having > 20% normative ne. It is proposed that melanephelinites defined in this manner can be further divided and that rocks formerly termed olivine nephelinite should now be called olivine melanephelinite, and that the pyroxene-phyric, olivine-poor melanephelinites should now be termed pyroxene melanephelinite.

Results of optical, thermomagnetic and electron microprobe analyses of titanomagnetite grains

This paper presents results of a study of titanomagnetite from specimens of ten different rock units. The rock units comprise trachytes, basalts, ignimbrites, nephelinites, olivine melanephelinites and welded tuffs from Kenya, with ages ranging from recent to Precambrian. The correlations of the stability index with opaque petrology and with thermomagnetic analyses of the titanomagnetite and titanomaghemite bearing specimens appear to be significant. Electron microprobe analyses of the titanomagnetite grains indicate a high percentage of “impurities” in the low stability index specimens and elevation of the Curie point in the high stability index specimens.

Paleomagnetic results from the Narosura and Magadi volcanics of Kenya

Results of a paleomagnetic study carried out on the exposed volcanic rocks on the western side of the South Kenya Rift Valley are presented. Nine stratigraphic groups ranging in age from Miocene to Pleistocene were sampled. The rocks consist of basalts, trachytes, nephelinites, melanephelinites, olivine melanephelinites and ignimbrites. Paleomagnetic poles obtained for different age ranges are as follows: Period I (0.64–0.72 Ma), 116°E, 85°N ( A 95 = 6°); Period II (1.6–6.9 Ma), 297°E, 84°N ( A 95 = 4°); Period III (12.0–15.0 Ma), 34°E, 80°N ( A 95 = 9°). The results for Period II show large secular variations which are in disagreement with the model predictions for near-equatorial sites.

Petrology of peridotite nodules from Ndonyuo Olnchoro, samburu district, central Kenya

Sodic alkaline volcanic rocks were extruded repeatedly in enormous volumes from Miocene time onward in Kenya, eastern Uganda and northern Tanzania. The volcanic cone of Ndonyuo Olnchoro in central Kenya consists of Recent olivine melanephelinite agglutinates and lava that contain many ejected ultramafic nodules. The nodules are divisible into two groups. The first group contains rocks consisting of magnesian olivine, orthopyroxene, and small amounts of chromian spinel and clinopyroxene. Harzburgite and lherzolite comprise this group and account for more than 95% of the peridotite nodules by volume. The second group of ultramafic nodules consists of websterite consisting of orthopyroxene, clinopyroxene and small amounts of chromian spinel. This group comprises less than 5% of the peridotite nodules by volume. These two groups of nodules are of different origins. The pressure and temperature of formation of the first group are estimated as 1200–1350°C 36–38 kbar. Their MgO σFeO ratios fall within the limit of variation of nodules from kimberlite and are higher than those for oceanic lherzolites. Mineralogical and chemical characters of the phases in the first group indicate more affinities with those in mantle-derived rocks than with peridotites derived by accumulation from a basaltic melt. The nodules were originally garnet peridotites and were transported upward into a lower pressure regime presumably by mantle convection. The pressure and temperature of formation of the second group of nodules are estimated as 1090° C 16 kbar. They were produced by crystallization from an alkaline magma in relatively deep levels of the continental crust. Both groups of nodules were transported to the surface when olivine melanephelinite was erupted.

The Alkaline Centre of Yelele and its Bearing on the Petrogenesis of other Eastern Uganda Volcanoes

ABSTRACTAn account is given of Yelele, a Miocene volcano, situated on the Turkana escarpment, north-east Uganda. It is composed of lavas and dykes of nephelinite, phonolite, tephrite, and trachyte together with olivine-bearing varieties, and has a central plug of ijolite and nepheline syenite.The lavas are described and compared with those of other eastern Uganda centres and the petrogenesis discussed in the light of experimental data from the Geophysical Laboratory of the Carnegie Institution of Washington.A northern (Yelele) plagioclase-bearing suite of lavas and a southern (Elgon) melilite-bearing suite are derived by different fractionation trends from an olivine melanephelinite parent which itself is the dense portion of a nephelinitic parent magma.

Petrographic Sub-provinces in the Tertiary to Recent Volcanics of Kenya

AbstractThree sub-provinces are recognized in the volcanics of the southern half of Kenya as follows:—(a) the Miocene phonolite sub-province, (b) the Mount Kenya phonolite/basanite sub-province, and (c) the Rift Valley trachyte/olivine basalt sub-province. Mela-nephelinitic lavas in the two phonolitic sub-provinces are shown to differ significantly in mineralogy, chemistry, and associated volcanics. The type of volcanic association likely to be related to carbonatite occurrences is briefly discussed.Areas of exposed Miocene phonolite and Plio-Pleistocene trachyte are much greater than those of associated basic lavas, while intermediate types are almost lacking. Calculations show that assimilation of gneissic basement rocks by basanite (or olivine mela-nephelinite) and by olivine basalt may contribute to the development of phonolite and trachyte respectively. Available supporting evidence is discussed, both from Kenya and from similar volcanic provinces elsewhere. The additional amount of salic derivatives “which can be produced in this way is small, however, relative to the volume of basic parent involved.

Origin of “petrified forest”

The study reports petrography, bulk major and trace element compositions of lamprophyric Devonian dykes in three areas of the Kola Alkaline Carbonatite Province (N Europe). Dykes in one of these areas, Kandalaksha, are not associated with a massif, while dykes in Kandaguba and Turij Mys occur adjacent (< 5 km) to coeval central multiphase ultramafic alkaline‑carbonatitic massifs. Kandalaksha dyke series consists of aillikites - phlogopite carbonatites and monchiquites. Kandaguba dykes range from monchiquites to nephelinites and phonolites; Turij Mys dykes represent alnöites, monchiquites, foidites, turjaites and carbonatites. Some dykes show extreme mineralogical and textural heterogeneity and layering we ascribe to fluid separation and crystal cumulation. Melt evolution of the dykes was modelled with Rhyolite-MELTS and compared with the observed order and products of the crystallization. Our results suggest that the studied rocks were related by fractional crystallization and liquid immiscibility. Primitive melts of aillikites or olivine melanephelinites initially evolved at P = 1.5–0.8 GPa without a SiO2 increase due to abundant clinopyroxene crystallization controlled by the CO2-rich fluid. At 1–1.1 GPa the Turij Mys melts separated immiscible carbonatite melt, which subsequently exsolved late carbonate-rich fluids extremely rich in trace elements. Kandaguba and Turij Mys melts continued to fractionate at lower pressures in the presence of hydrous fluid to the more evolved nephelinite and phonolite melts. The studied dykes highlight the critical role of the parent magma chamber in crystal fractionation and magma diversification. The Kandalaksha dykes may represent a carbonatite – ultramafic lamprophyre association, which fractionated at 45–20 km in narrow dykes on ascent to the surface and could not get more evolved than monchiquite. In contrast, connections of Kandaguba and Turij Mys dykes to their massif magma chambers ensured the sufficient time for fractionation, ascent and a polybaric evolution. This longevity generated more evolved rock types with the higher alkalinity and an immiscible separation of carbonatites.