The Vuoriyarvi Paleozoic alkaline–ultramafic complex with carbonatites is made up of a great diversity of rocks with various ore mineralization. The paper presents data on the geochemistry of pyroxenites, phoscorites, and carbonatites from the Neskevara deposit of rare metals. The pyroxenites of the rare-metal deposit are significantly enriched in Nb, Ta, and Th relative to the primitive mantle and the primary alkaline–ultramafic melt composition calculated for the Kola alkaline province and are characterized by high Nb/Ta, Zr/Hf, and Th/U ratios of 29, 35, and 14, respectively. HFSE are maximally enriched in the phoscorites and carbonatites of stages II and III, with the highest concentrations of Nb (16 000 ppm), Th (2800 ppm), and Zr (4000 ppm) found in the calcite–tetraferriphlogopite phoscorites, in which pyrochlore crystallization on the liquidus was identified. The rocks of the carbonatite series are strongly enriched in LREE relative to carbonaceous chondrite. The calcite–dolomite carbonatites of the late magmatic–carbothermal stage show REE enrichment up to 25 800 ppm. The chondrite-normalized REE patterns and (La/Yb) N ratio indicate that REE were systematically more strongly fractionated in the sequence pyroxenite (70)—phoscorite (90)—calcite (540) and dolomite (3790) carbonatites The crystallization sequence of minerals in the rare-metal phoscorites and carbonatites of intermediate stages indicates that magnetite and pyrochlore crystallized nearly simultaneously. The crystallization temperatures of such associations are, according to data of the magnetite–ilmenite thermometer, lower than 500–600°C, at ∆NNO = –0.3 and + 1.5 and corresponded to the temperature at which the rare-metal ore mineralization of the main stage was formed.

The paper presents petrographic, mineralogical, and geochemical data on dunites, pyroxenites, peridotites, and gabbroids of the Kamchatsky Mys ophiolite. These data were acquired to distinguish cogenetic assemblages of igneous rocks, gain an insight into their geodynamic settings, and test various criteria of genetic links between the different magmatic rocks of ophiolites. The ultramafic and mafic rocks are shown to belong to two series, which differ in the compositions of the primary minerals, bulk rocks, and estimated trapped melts. The rocks of these series are found out to have been produced by geochemically different melts in different geodynamic settings, and during different episodes of mantle magmatism. The rocks of the high-Ti series (gabbro of the Olenegorsk massif, dunite and melanogabbro xenoliths in them, and vein gabbro in these xenoliths) crystallized from N-MORB melts in an oceanic spreading center. The rocks of the low-Ti series (dunite, pyroxenite, and gabbro veins in the residual spinel peridotites of the Mount Soldatskaya massif, as well as pyroxenite, peridotite, and gabbro alluvium and diluvium in the central and western parts of the peninsula) crystallized from water-rich boninite melts in relation to initial subduction magmatism. Taken into account the absence of boninite lavas from the Kamchatsky Mys ophiolite, the plutonic ultramafic rocks (including the rocks of the veins) might be the only evidence of subduction boninitic magmatism in the ophiolites. It was demonstrated that conclusions about the geodynamic settings of plutonic ultramafic and mafic rocks and recognition of cogenetic relations of these rocks with spatially associated basalts are more reliable when derived from the compositions of the trapped melts, which are estimated from their bulk geochemistry and primary mineral compositions, than when they are based on the mineral compositions only.

The paper presents newly acquired geochemical and mineralogical data on carbonatites and fluorapatite of the Newania intrusive complex, India. A magmatic−metamorphic hypothesis is proposed to explain the origin of this complex. The Newania carbonatites are comparable to the average composition of ferro- and magnesiocarbonatites worldwide in terms of Ca, Fe, Mg, Mn, Na, K, Al, Ti, P, and Sr contents but is depleted in Ba, Ta, Zr, Th, and REE. Fluorapatite and monazite-(Ce) are the main P, Sr, Th, and REE concentrators in the rocks, whereas U is concentrated mostly in U-rich pyrochlore. The major chemical changes in the fluorapatite can be described in a generalized form by the following reaction: REE3+ + Na+ ↔ 2Ca2+. The fluorapatite is relatively poor in radioactive elements and contains no more than 0.2 wt

Melt inclusions were investigated in the minerals of dacite tephra of the largest Holocene eruption (7900 years) of Khangar volcano, Sredinny Range of Kamchatka. Melt compositions correspond to rhyolite (SiO2 = 70–77 wt %, Na2O+K2O = 6–7 wt %) with ~5 wt % H2O. The melts show a minor negative Nb anomaly and lesser HREE depletion (La/Yb is ~7.1) compared to those of Ichinsky Volcano, another active volcano of the Sredinny Range of Kamchatka. It was determined that different phenocryst assemblages were formed within temperature ranges of 750–785 and 830–870°C. Evidence for the assimilation of granite-gneiss basement by magmas of Khangar volcano are discussed.

In this work, mineralogical and geochemical data are presented for sulfide-rich phoscorites and carbonatites in the Kovdor massif. The PGE and Ag-bearing mineralization of bornite–chalcopyrite and Ag‑bearing mineralization of pyrrhotite–chalcopyrite associations were investigated. In carbonatite stage formation of massif, the noble metal minerals occurred during evolution of alkaline–ultrabasic melt and after separation of primary sulfide melt enriched in PGE, Au and Ag. According to the observed relationships, the minerals of PGE, Au, and Ag in bornite–chalcopyrite association are crystallized sequentially from magmatic to hydrothermal stages. Crystallization of Os, Ir, Pt and Pd minerals (erlichmanite, rustenburgite, isoferroplatinum, mertieite–II, etc.) occurred at temperature close to 480°С, while further decrease in the temperature and an increase in the Cu and Fe activity in the melt leads to the crystallization of Sb, Pb, As, Bi and Te-bearing minerals (sperrylite, tatyanaite, moncheite, stumpflite, etc.). Formation of Au and Ag-bearing minerals (electrum, silver, stromeyerite, lenaite, etc.) occurred at temperatures below 300 °C with relatively low sulfur activity. In carbonatites and phoscorites of the middle and late magmatic stages enriched with magnetite, pyrrhotite–chalcopyrite association with silver-bearing minerals was formed at temperatures below 300°C. Ag-bearing minerals were produced during hydrothermal recrystallization of Cu–Fe–Ni sulfides at temperature close to 150°C.

— A set of experiments was carried out in the system NaAlSi 3 O 8 –FeO–NiO–CoO–SiC–NaH 2 PO 4 at 1550°C, 4 GPa, and oxygen fugacity ( f O 2 ) 0.5–2.9 log. units below the iron–wüstite (IW) buffer to estimate how C–O–H components can affect Ni, Co, and P partition between silicate melt and a liquid metallic phase at redox conditions under which the metallic phase is segregated into melting products of the early reduced mantles of the Earth and other planetary bodies. It has been established that the Ni, Co, and P partition coefficients D (М) met/sil between silicate melts saturated with carbon and containing dissolved C–O–H volatiles (mainly in the form of OH groups, H 2 and CH 4 ) at relatively oxidized conditions ( f O 2 > IW – 1.5) correspond to D (М) met/sil values expected of metal–silicate melt equilibrium in volatile-free systems at analogous P , T , f O2 , and nbo/t parameters. Under more reduced conditions ( f O 2 ≤ IW – 2), the presence of C–O–H volatiles leads to a decrease in D (М) met/sil for Ni and P compared to that in “dry” melts. This difference increases with decreasing f O 2 and reaches ~0.5 and more than one order of magnitude for Ni and P, respectively, at f O 2 = IW – 2.9. The effect of volatiles on D (Co) met/sil is much weaker, and hence, a decrease in f O 2 leads to that D (Ni) met/sil and D (Co) met/sil converge. The Raman spectra of the experimental glasses and their SIMS analyses for hydrogen show that water content (OH + H 2 O) in the melts decreases with decreasing f O 2 , whereas the contents of CH 4 and complexes with C–H bonds significantly increases. The likely reasons for the decrease in D (М) met/sil under strongly reduced conditions may be changes in the structure of the silicate melts and the origin of complex compounds of siderophile elements with volatiles in these melts.

Mineral zoning in fenites around miaskite intrusions of the Vishnevye Mountains complex can be interpreted as a magmatic-replacement zonal metasomatic aureole (in D.S. Korzhinskii’s understanding): the metasomatic transformations of the fenitized gneisses under the effect of deep alkaline fluid eventually resulted in the derivation of nepheline syenite eutectic melt. Based on the P–T–fO2 parameters calculated from the composition of minerals coexisting in the successive zones, isobaric–isothermal fO2–aSiO2 and µNa2O–µAl2O3 sections were constructed with the Perplex program package to model how the fenites interacted with H2O–CO2 fluid (in the Na–K–Al–Si–Ca–Ti–Fe–Mg–O–H–C system). The results indicate that the fluid–rock interaction mechanisms are different in the outer (fenite) and inner (migmatite) parts of the zonal aureole. Its outer portion was dominated by desilication of rocks, which led, first, to quartz disappearance from these rocks and then to an increase in the Al# of the coexisting minerals (biotite and clinopyroxene). In the inner part of the aureole, fenite transformations into biotite–feldspathic metasomatic rocks and nepheline migmatite were triggered by an increase in the Na and Al activities in the system alkaline H2O–CO2 fluid–rock. As a consequence, the metasomatites were progressively enriched in Al2O3 and alkalis, and these transformations led to the development of biotite in equilibrium with K–Na feldspar and calcite at the sacrifice of pyroxene. The further introduction of alkalis led to the melting of the biotite–feldspathic metasomatites and the origin of nepheline migmatites. The simulated model sequence of metasomatic zones that developed when the gneiss was fenitized and geochemical features of the successive zones (differences in the LILE and REE concentrations in the rocks and minerals of the fenitization aureole and the Sm–Nd isotope systematics of the rocks of the alkaline complex) indicate that the source of the fluid responsible for the origin of zonal fenite–miaskite complexes may have been carbonatite, a derivative of mantle magmas, whereas the miaskites were produced by metasomatic transformations of gneisses and subsequent melting under the effect of fluid derived from carbonatite magmas.

The Pesyanoe aubrite is an essentially polymict regolith breccia comprised by fragments of different highly magnesian pyroxenitic lithologies: albite; anorthoclase and labradorite‐bearing pyroxenites; diopside and magnesian augite pyroxenites; roedderite‐ and forsterite‐bearing pyroxenites; and impact glasses; porphyritic and melt matrix breccia fragments; FeO‐rich chondritic inclusions; and exotic oxidized clasts. The parent magma of Pesyanoe probably was carbon saturated, as suggested by pyroxenite fragments containing igneous‐textured carbon phases, possibly graphite. The composition of feldspar and trapped melt inclusions in enstatite indicates occurrence of at least three metaluminous melt sources with different (K + Na)/Al and K/(K + Na) atomic ratios on the Pesyanoe parent body and has records of K and Na loss from the melt, possibly due to evaporation from the parent body surface. The roedderite‐ and forsterite‐bearing rocks probably crystallized from a peralkaline melt. We propose that peralkaline melt could be formed from a metaluminous melt(‐s) due to gravitational segregation of djerfisherite‐bearing metal‐sulfide liquid in the lower horizon of the magma chamber and following oxidation of the magma. This should lead to enrichment of silicate melt in K 2 O and Na 2 O and increasing of (K + Na)/Al > 1, allowing forsterite and roedderite to crystallize. Rocks enriched in K and containing rare K‐bearing minerals were found among both magmatic and melt rocks. This may imply an insignificant role of regolith transport in the process of the breccia’s formation and, therefore, an origin of all of the breccia components from a local region of the Pesyanoe parent body, probably from a single complex igneous massif.

We report the first combined investigation (neutron activation, X-ray fluorescence, and electron microprobe analysis) of mineral forms of Au and Ag and noble metal distribution in the sulfide-bearing phoscorites and carbonatites of the Guli alkaline ultrabasic massif (Polar Siberia) and magnetite and sulfide separates from these rocks. The highest noble metal contents were observed in the sulfide separates from the carbonatites: up to 2.93 Pt, 61.6 Au, and 3.61 ppm Ag. Pyrrhotite, djerfisherite, chalcopyrite, and pyrite are the most abundant sulfides and the main hosts for Au and Ag. The latest assemblage of chalcopyrite, Ag-rich djerfisherite, lenaite, sternbergite, and native silver shows significant Ag concentrations. The wide occurrence of K sulfides and presence of multiphase inclusions in pyrrhotite consisting of rasvumite, K‒Na–Ca carbonate, carbocernaite, strontianite, galena, chalcopyrite, sternbergite, lenaite, and native silver suggest that the sulfides were formed at high activities of K, Na, Sr, LREE, F, Cl, and S. Chlorine shows high complex-forming capacity to Ag and could be an agent of noble metal transport in the carbonatites. Crystallization of the early djerfisherite–pyrrhotite assemblages of the phoscorites and carbonatites began at a temperature not lower than 500°C and continued up to the formation of late Ag-bearing sulfides at temperatures not higher than 150°C. The carbonatite-series rocks could be enriched in Au and Ag during late low-temperature stages and serve as a source for Au placers.

Unusual agpaitic syenites containing up to 25 vol.% lamprophyllite-group minerals (lamprophyllite, fluorlamprophyllite, barytolamprophyllite, and the new mineral species fluorbarytolamprophyllite, IMA 2016–089) have been discovered in the Niva intrusion and Mokhnatye Roga alkaline dyke belonging to the Kola Alkaline Province, northwestern Russia. The other main components of the rocks are potassium feldspar, Ti-rich aegirine-augite, aenigmatite, alkaline amphiboles, astrophyllite, natrolite, and ferripyrophyllite. Three generations of lamprophyllite-group minerals can be distinguished based on their morphological features. The new mineral fluorbarytolamprophyllite is the F-dominant analogue of barytolamprophyllite and the Ba-dominant analogue of fluorlamprophyllite. It represents the early generation of lamprophyllite-group minerals (LGM) and forms brown prismatic crystals, their radial aggregates and marginal zones of fluorlamprophyllite crystals. The lustre of the new mineral is vitreous to pearly. Mohs hardness is 2.5. Dcalc is 3.662 g/cm3. The mineral is optically biaxial (+), α = 1.738(3), β = 1.745(4), γ = 1.777(4) (589 nm), 2 V (meas.) = 55(5)°, 2 V (calc.) = 51°. The chemical composition (electron microprobe, water determined by TGA, wt.%) is: Na2O 10.01, K2O 2.65, MgO 0.43, CaO 0.64, SrO 5.59, BaO 16.23, MnO 0.50, FeO 4.44, Al2O3 0.08, TiO2 27.31, ZrO2 0.22, Nb2O5 0.91, Ta2O5 0.15, SiO2 29.35, F 2.41, H2O 0.26, total 101.18. The empirical formula based on 18 anions is (Ba0.865Sr0.44K0.46Na0.26)Σ2.025(Na2.38Ca0.09Fe0.47Mn0.06)Σ3.00(Ti2.79Mg0.09Fe0.035Nb0.06Zr0.015Ta0.01)Σ3.00(Si3.99Al0.01)Σ4.00 O16[F1.04O0.72(OH)0.24]Σ2.00. The IR spectrum is given. The strongest lines of the powder X-ray diffraction pattern are [d, Å (I,%) (hkl)]: 9.692 (40) (200), 3.726 (59) (−311), 3.414 (67) (311), 3.230 (96) (300), 3.013 (53) (−5–11), 2.780 (100) (221), 2.662 (52) (002). The crystal structure has been solved and refined to R1 = 5.07 based on 2897 independent reflections with I > 2σ(I). Fluorbarytolamprophyllite is monoclinic, space group C2/m. The unit-cell parameters refined from the powder data are: a = 19.520(5), b = 7.0995(17), c = 5.3896(20) Å, β = 96.657(23)°; V = 741.86(24) Å3, Z = 2. At Niva and Mokhnatye Roga, most of the LGM were formed during magmatic stage of syenite crystallization from alkaline melt enriched in Na, K, Ba, Fe, Ti and F. Compositional variation of the examined LGM and their textural relations show changes in the Sr/Ba ratio in the parental melt and increasing activity of F and Ba in derivatives fluids as the main factors driving this variation.

The Ust’-Belaya terrane (Chukotka, NE Russia), belonging to the West Koryak fold belt, is made of mantle and crustal ultramafic-mafic complexes which originated during several discrete episodes of magmatic activity in the Neoproterozoic, the late Neoproterozoic-Cambrian and the early-middle Triassic and accreted to the Asian continental margin in the early Cretaceous. This paper focuses on the latest magmatic episode expressed in intrusion of microgabbro dikes and nearly coeval metamorphism superimposed on both ancient complexes and the dikes. We present original 40Ar/39Ar ages, mineral and bulk-rock chemistry of the microgabbro dikes, metamorphosed dike and vein cutting ultramafic-mafic complexes. Dike microgabbros resemble differentiated arc-tholeiitic magmas originated in a subduction setting. Differentiated magmas intruded into much older spinel peridotites and dunites located at mid-crustal levels. Intrusion and crystallization of these magmas was followed by down-going movement of spinel peridotites and rocks of the mantle-crust transition zone towards a mantle wedge where they were metamorphosed at high-P conditions. This metamorphism resulted in transformation of microgabbro to garnet amphibolite, diorite to albite-zoisite-paragonite-pargasite rock and spinel peridotites to metaperidotites. P-T parameters of this metamorphism reconstructed based on mineral assemblage of garnet amphibolite correspond to those of epidote amphibolite – amphibolite – amphibole eclogite facies transition. The peculiar zoisite (clinozoisite)-paragonite mineral assemblage typical of metamorphosed vein rock indicates high-P metamorphic conditions of epidote-amphibolite facies.

Kyshtymites are the unique corundum-blue sapphire-bearing variety of anorthosites of debatable geological origin found in the Ilmenogorsky-Vishnevogorsky complex (IVC) in the South Urals, Russia. Their mineral association includes corundum-sapphire, plagioclase (An61–93), muscovite, clinochlore, and clinozoisite. Zircon, churchite-(Y), monazite-(Ce), and apatite group minerals are found as accessory phases. Besides, churchite-(Y) and zircon are also identified as syngenetic solid inclusions within the sapphires. In situ Laser Ablation Inductively Coupled Plasma Mass Spectrometry (LA-ICP-MS) U-Pb zircon geochronology showed the ages at about 290–330 Ma linked to the Hercynian orogeny in IVC. These ages are close to those of the syenitic and carbonatitic magmas of the IVC, pointing to their syngenetic origin, which is in agreement with the trace element geochemistry of the zircons demonstrating clear magmatic signature. However, the trace element composition of sapphires shows mostly metamorphic signature with metasomatic overprints in contrast to the geochemistry of zircons. The reason for this discrepancy can be the fact that the discrimination diagrams for sapphires are not as universal as assumed. Hence, they cannot provide an unambiguous determination of sapphire origin. If it is true and zircons can be used as traces of anorthosite genesis, then it can be suggested that kyshtymites are formed in a magmatic process at 440–420 Ma ago, most probably as plagioclase cumulates in a magma chamber. This cumulate rock was affected by a second magmatic event at 290–330 Ma as recorded in zircon and sapphire zoning. On the other hand, Ti-in-zircon thermometer indicates that processes operated at relatively lower temperature (<900 °C), which is not enough to re-melt the anorthosites. Hence, zircons in kyshtymites can be magmatic but inherited from another rock, which was re-worked during metamorphism. The most probable candidate for the anorthosite protolith is carbonatites assuming that metamorphic fluids could likely leave Al- and Si-rich residue, but removed Ca and CO2. Further, Si is consumed by the silicification of ultramafic host rocks. However, kyshtymites do not show clear evidence of pronounced metasomatic zonation and evidence for large volume changes due to metamorphic alteration of carbonatites. Thus, the obtained data still do not allow for univocal reconstruction of the kyshtymite origin and further investigations are required.

Новые данные по геохимии корунда метасоматизированных ксенолитов «Рыжая незнакомка» и «Кукисвумчорр», Хибинский щелочной массив (Кольский полуостров)Филина М.И. 1 , Сорокина Е

Впервые на примере щелочно-ультраосновного Гулинского массива (Полярная Сибирь) в сульфидсодержащих фоскоритах и карбонатитах, выделенных из них магнетитовых и сульфидных концентратов, проведено комплексное исследование (нейтронно-активационный, рентгенофлуоресцентный и рентгеноспектральный зондовый анализы) минеральных форм нахождения Au и Ag и распределения благородных металлов. Установлено, что сульфидные концентраты карбонатитов являются наиболее обогащенными в отношении благородных металлов ― до 2.93 ppm Pt, 61.6 ppm Au и 3.61 ppm Ag. Пирротин, джерфишерит, халькопирит и пирит — наиболее распространенные сульфиды и главные концентраторы Au и Ag. Самый поздний парагенезис, представленный халькопиритом, Ag-обогащенным джерфишеритом, ленаитом, штернбергитом и самородным серебром, содержит значимые концентрации Ag. Согласно широкому распространению калиевых сульфидов и выявленным в пирротине полифазным включениям расвумита, K-Na-Ca карбоната, карбоцернаита, стронцианита, галенита, халькопирита, штернбергита, ленаита и самородного серебра, сульфиды формировались в условиях повышенной активности K, Na, Sr, LREE, F, Cl и S. Хлор, обладающий высокой способностью к комплексообразованию с серебром, мог быть агентом переноса благородных металлов в карбонатитах. Кристаллизация ранних джерфишерит-пирротиновых ассоциаций фоскоритов и карбонатитов начиналась при температуре не менее 500°С и продолжалась до образования поздних Ag-содержащих сульфидов при температуре не более 150°C. Породы карбонатитовой серии на поздних низкотемпературных стадиях могут обогащаться Au и Ag и являться одним из источников при образовании золотоносных россыпей.

New geochemical, mineralogical, and Rb–Sr and Sm–Nd isotopic data have been obtained on corundum plagioclasites–kyshtymites from the 5th Versta deposit (South Urals, Russia). The genetic link of miaskites and kyshtymites is shown. The formation of the kyshtymites is associated with the redistribution and accumulation of aluminum, calcium, HFSE, and LIL-elements at the stage of tectonic-metamorphic deformations of the Ilmenogorsky–Vishnevogorsky alkaline complex.

M. A. Ivanova, C. A. Lorenz, M. Humayun, K. Richter, C. M. Corrigan, I. A. Franchi, A. B. Verchovsky, E. V. Korochantseva, V. V. Kozlov, S. N. Teplyakova, Kononkova N. N., and A. V. Korochantsev, Vernadsky Institute of Geochemistry and Analytical Chemistry, Moscow 119991, Russia; meteorite2000@mail.ru, National Museum of Natural History, Smithsonian Institution, USA; National High Magnetic Field Laboratory and Department of Earth, Florida State University, USA; Planetary and Space Sciences Research Institute, Open University, UK, Mailcode XI2, NASA JSC, USA Oxford Instruments OM & Gatan Inc., Moscow, Russia .