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Accessory columbite-(Fe) to tantalite-(Fe) from three granitic pegmatites of the Tatric Superunit (Bratislava Massif of the Malé Karpaty Mts., Bojná Massif of the Považský Inovec Mts. and Suchý Massif of the Strážovské Mts.) was used for dating by the in-situ LA–ICP–MS U–Pb method. The columbite–tantalite crystals were sampled from the most fractionated pegmatite dykes of the beryl–columbite subtype situated in the pre-Alpine, Paleozoic crystalline basement of the Tatric Superunit, Western Carpathians (western and central Slovakia). The obtained columbite–tantalite Concordia ages are as follows: 354.5 ± 4.5 Ma (Jezuitské Lesy pegmatite, the Bratislava granite Massif), 360 ± 5.0 Ma (Moravany nad Váhom, Striebornica Ridge pegmatite, the Bojná Massif), and 352 ± 8.5 Ma (Liešťany, Bystrý Hill pegmatite, the Suchý Massif). The columbite–tantalite ages show Mid-Variscan formation of rare-element pegmatites from the Devonian/Carboniferous boundary to Tournaisian stage, which is coeval with the emplacement of cogenetic granites during the main phase of Variscan intracontinental subduction and collision. The obtained columbite–tantalite age interval of rare-element granitic pegmatites of the Tatric Superunit (~360 to 350 Ma) is generally older than the ages of Be- and Li-rich rare-element pegmatites of the Moldanubian Superunit in the Bohemian Massif (~340 to 320 Ma). The rare-element granitic pegmatites of the Austroalpine Superunit (Eastern Alps) are significantly younger (~290 to 240 Ma) because they were formed in an extension regime during the Permian to Early Triassic post-Variscan orogenic collapse. [ABSTRACT FROM AUTHOR]

Titanite belongs to the common accessory minerals in Variscan (~360–350 Ma) metaluminous to slightly peraluminous tonalites to granodiorites of I-type affinity in the Tatric and Veporic Units, the Western Carpathians, Slovakia. It forms brown tabular prismatic-dipyramidal crystals (~0.5 to 10 mm in size) in association with quartz, plagioclase, and biotite. Titanite crystals commonly shows oscillatory, sector and convolute irregular zonal textures, reflecting mainly variations in Ca and Ti versus Al (1–2 wt. % Al2O3, 0.04–0.08 Al apfu), Fe (0.6–1.6 wt. % Fe2O3, 0.02–0.04 Fe apfu), REE (La to Lu + Y; ≤4.8 wt. % REE2O3, ≤ 0.06 REE apfu), and Nb (up to 0.5 wt. % Nb2O5, ≤0.01 Nb apfu). Fluorine content is up to 0.5 wt. % (0.06 F apfu). The compositional variations indicate the following principal substitutions in titanite: REE3+ + Fe3+ = Ca2+ + Ti4+, 2REE3+ + Fe2+ = 2Ca2+ + Ti4+, and (Al, Fe)3+ + (OH, F)− = Ti4+ + O2−. The U–Pb SHRIMP dating of titanite reveal their Variscan ages in an interval of 351.0 ± 6.5 to 337.9 ± 6.1 Ma (Tournaisian to Visean); titanite U–Pb ages are thus ~5 to 19 Ma younger than the primary magmatic zircon of the host rocks. The Zr-in-titanite thermometry indicates a relatively high temperature range of titanite precipitation (~650–750 °C), calculated for assumed pressures of 0.2 to 0.4 GPa and a(TiO2) = 0.6–1.0. Consequently, the textural, geochronological and compositional data indicate relatively high-temperature, most probably early post-magmatic (subsolidus) precipitation of titanite. Such titanite origin could be connected with a subsequent Variscan tectono-thermal event (~340 ± 10 Ma), probably related with younger small granite intrusions and/or increased fluid activity. Moreover, some titanite crystals show partial alteration and formation of secondary titanite (depleted in Fe and REE) + allanite-(Ce) veinlets (Sihla tonalite, Veporic Unit), which probably reflects younger Alpine (Cretaceous) tectono-thermal overprint of the Variscan basement of the Western Carpathians.

Three representative A-type rhyolitic rock samples from the Muráň Nappe of the inferred Silicic Unit of the Inner Western Carpathians (Slovakia) were dated using the high-precision SIMS U–Pb isotope technique on zircons. The geochronological data presented in this paper is the first in-situ isotopic dating of these volcanic rocks. Oscillatory zoned zircon crystals mostly revealed concordant Permian (Guadalupian) ages: 266.6 ± 2.4 Ma in Tisovec-Rejkovo (TIS-1), 263.3 ± 1.9 Ma in Telgárt-Gregová Hill (TEL-1) and 269.5 ± 1.8 Ma in Veľká Stožka-Dudlavka (SD-2) rhyolites. The results indicate that the formation of A-type rhyolites and their plutonic equivalents are connected to magmatic activity during the Permian extensional tectonics and most likely related to the Pangea supercontinent break-up.

This paper presents geochronological data for the volcanic dykes located in the northern Považský Inovec Mts. The dykes are up to 5 m thick and tens to hundreds of metres long. They comprise variously inclined and oriented lenses, composed of strongly altered grey-green alkali basalts. Their age was variously interpreted and discussed in the past. Dykes were emplaced into the Tatricum metamorphic rocks, mostly consisting of mica schists and gneisses of the Variscan (early Carboniferous) age. Two different methods, zircon SHRIMP and monazite chemical dating, were applied to determine the age of these dykes. U-Pb SHRIMP dating of magmatic zircons yielded the concordia age of 260.2 ± 1.4 Ma. The Th-U-Pb monazite dating of the same dyke gave the CHIME age of 259 ± 3Ma. Both ages confirm the magmatic crystallization at the boundary of the latest Middle Permian to the Late Permian. Dyke emplacement was coeval with development of the Late Paleozoic sedimentary basin known in the northern Považský Inovec Mts. and could be correlated with other pre-Mesozoic Tethyan regions especially in the Southern Alps.

A unique case of low-temperature metamorphic (hydrothermal) overprint of peraluminous, highly evolved rare-metal S-type granite is described. The hidden Dlhá dolina granite pluton of Permian age (Western Carpathians, eastern Slovakia) is composed of barren biotite granite, mineralized Li-mica granite and albitite. Based on whole-rock chemical data and evaluation of compositional variations of rock-forming and accessory minerals (Rb-P-enriched K-feldspar and albite; biotite, zinnwaldite and di-octahedral micas; Hf-(Sc)-rich zircon, fluorapatite, topaz, schorlitic tourmaline), the following evolutionary scenario is proposed: (1) Intrusion of evolved peraluminous melt enriched in Li, B, P, F, Sn, Nb, Ta, and W took place followed by intrusion of a large body of biotite granites into Paleozoic metapelites and metarhyolite tuffs; (2) The highly evolved melt differentiated in situ forming tourmaline-bearing Li-biotite granite at the bottom, topaz-zinnwaldite granite in the middle, and quartz albitite to albitite at the top of the cupola. The main part of the Sn, Nb, and Ta crystallized from the melt as disseminated cassiterite and Nb-Ta oxide minerals within the albitite, while disseminated wolframite appears mainly within the topaz-zinnwaldite granite. The fluid separated from the last portion of crystallized magma caused small scale greisenization of the albitite; (3) Alpine (Cretaceous) thrusting strongly tectonized and mylonitized the upper part of the pluton. Hydrothermal low-temperature fluids enriched in Ca, Mg, and CO2 unfiltered mechanically damaged granite. This fluid-driven overprint caused formation of carbonate veinlets, alteration and release of phosphorus from crystal lattice of feldspars and Li from micas, precipitating secondary Sr-enriched apatite and Mg-rich micas. Consequently, all bulk-rock and mineral markers were reset and now represent the P-T conditions of the Alpine overprint.

A hydrothermal quartz vein with REE-U-Au mineralization in the Zimná Voda (Gemeric Unit, Western Carpathians, Slovakia) is associated with contact metamorphism between Permian granites and host phyllites and metaquartzites. It contains unique REE minerals of the monazite and xenotime groups. Monazite-(Ce), monazite-(Nd), monazite-(Sm), and Gd-dominant monazite ["monazite-(Gd)"], along with xenotime-(Y) to Gd-dominant xenotime ["xenotime-(Gd)"] and Gd-rich hingganite-(Y) show heterogeneous compositions and reflect a strong fractionation trend toward the enrichment of MREE (Sm to Dy), particularly Gd. Here, the gadolinium abundance reported in "monazite-(Gd)" (≤23.4 wt% Gd2O3) and Gd-rich xenotime-(Y) to "xenotime-(Gd)" (≤28.7 wt% Gd2O3) and accompanied by Gd-rich hingganite-(Y) (≤15.8 wt% Gd2O3), is among the highest Gd concentrations ever reported in natural minerals. The Gd-richest compositions show the following formulas: (Gd0.31Sm0.24 Nd0.15Ce0.10La0.05Dy0.03Y0.03...)0.98PO4 ["monazite-(Gd)"], (Gd0.36Y0.32Dy0.13Sm0.08Tb0.05...)0.98 (P0.96As0.04)1.00O4 ["xenotime-(Gd)"] and (Y0.71Gd0.43Dy0.23Sm0.22Tb0.06Er0.04Nd0.06...Ca0.06)1.96 ( ◻ 0.87 Fe 0.13 2 +) 1.00 (B e 1.82 B 0.18 ) 2.00 (S i 1.90 A s 0.10 ) 2.00 O 8 (O H 1.70 O 0.30 ) 2.00 [hingganite-(Y)]. The MREE-rich monazites, xenotimes, and hingganite-(Y) precipitated in response to the alteration of primary uraninite, brannerite, and fluorapatite by low-temperature hydrothermal fluids of heterogeneous compositions on a microscale. These are responsible for the strong enrichment of individual MREE, especially Gd in the secondary minerals. This is accompanied by the advancing development of the W-type tetrad effect on REE through monazite species. The substantial incorporation of Gd into both REE-selective monazite and xenotime structures that are accompanied by LREE vs. HREE segregation indicates the possibility of differently sized REE3+ miscibility in REEPO4 solid solutions, as well as the stabilization of the Gd-rich orthophosphate structure by substitution of the remaining A-site cations with smaller HREE+Y in the xenotime-type, and/or larger LREE in the monazite-type structure. [ABSTRACT FROM AUTHOR]

The beryllium silicate minerals phenakite and bertrandite have been identified in granitic pegmatite dykes of the beryl-columbite subtype of Variscan age (~340−355 Ma), associated with S- to I-type granitic rocks of the Tatric Superunit, Western Carpathians (Slovakia). The two beryllium silicates and associated minerals were characterised by electron microprobe analysis, back-scattered electron petrography and cathodoluminescence imagery, X-ray diffraction and micro-Raman techniques. Phenakite and bertrandite form euhedral-to-anhedral crystals and aggregates in irregular domains and veinlets replacing primary magmatic beryl. A detailed textural study revealed a close genetic association of phenakite and bertrandite with secondary fine-grained quartz, K-feldspar and muscovite. Locally, clay phyllosilicate minerals, (with compositions similar to those of Fe-dominant hydrobiotite, beidellite, nontronite and saponite) occur as the youngest minerals. During the post-magmatic (hydrothermal) stage of the pegmatites, infiltration of aqueous K-bearing fluids at T ≈ 200–400°C resulted in the breakdown of magmatic beryl to secondary assemblages containing phenakite and bertrandite. [ABSTRACT FROM AUTHOR]

Two representative peraluminous A-type rhyolite samples from the Poniky area (the Drienok Nappe) in the Inner Western Carpathians (central Slovakia) were dated using the LA–ICP–MS U–Pb zircon method. These geochronological data represent the first in-situ isotopic dating study undertaken on these volcanic rocks. Oscillatory zoned zircon crystals yielded concordant Permian (Guadalupian) ages of 271.0 ± 1.5 Ma and 267.5 ± 1.6 Ma for the Poniky rhyolites, which supports their genetic link to the analogous mid-Permian (Guadalupian) rhyolites of adjacent Muráň and Vernár nappes. The Ti-in-zircon geothermometry (corrected using the activities of SiO2 and TiO2 using the rhyoliteMELTS thermodynamic software) indicate mean zircon crystallization temperatures of ~910 to 935 °C for the Poniky rhyolites. The results indicate pulses of anorogenic A-type rhyolitic magmatism were coeval with intrusions of granitic rocks associated with an intraplate extensional tectonic regime triggered by asthenospheric upwelling in the Western Carpathian region. The A-type magmatism was most likely related to the break-up of the Pangea supercontinent during the mid-Permian (~270–260 Ma). [ABSTRACT FROM AUTHOR]

Silicate minerals enriched in V, Cr and Mn including garnets and epidote-supergroup members, in association with amphiboles, albite, hyalophane, titanite, chamosite, sulfides and other minerals occur in Devonian black shales near Čierna Lehota in the Strážovské vrchy Mountains, Slovakia. The garnets have high concentrations of V, Cr and Mn (up to 17 wt.% V2O3, ≤11 wt.% Cr2O3 and ≤ 21 wt.% MnO) and several compositional types. Vanadian-chromian grossular (Grs 1) usually preserves primary metamorphic oscillatory zoning, whereas solid solutions between goldmanite (Gld 2A,B), V- and Cr-rich grossular and spessartine (Grs 2A,B, Sps 2) form irregular domains or crystals with variable zoning. Dominant substitutions in the garnets include CaMn–1 and (V,Cr)Al–1, resulting in coupled Ca(V,Cr)Mn–1Al–1. Epidote-supergroup minerals occur as abundant anhedral crystals with variable compositional zoning. Nearly all crystals have a complete zoning sequence beginning with REE -rich allanite-(La), followed by mukhinite and by V- and Cr-rich clinozoisite to mukhinite and V- and Cr-poor clinozoisite. In common with garnets, the epidote-supergroup minerals are enriched in V, Cr and Mn (<7 wt.% V2O3, <5 wt.% Cr2O3 and <3 wt.% MnO). Lanthanum is the dominant REE (up to 11.5 wt.% La2O3) in allanite-(La). The composition of epidote-supergroup minerals is controlled by REE Fe2+(CaAl)–1, REE Mg(CaAl)–1, REE Mn2+(CaAl)–1 and REE Fe2+(CaFe3+)–1 substitutions introducing REE , together with VAl–1 and CrAl–1 substitutions. The negative Ce and slightly positive Eu anomalies displayed in chondrite-normalized patterns and enrichment in V, Cr and Mn are ascribed to the geochemical properties of the protolith. The minerals investigated exhibit multi-stage evolution: (1) presumed low-grade greenschist-facies metamorphism; and (2) development of V- and Cr-rich zones in both garnet- and epidote-supergroup minerals which result from late-Variscan contact metamorphism due to granitic intrusion of the Suchý Massif. Decreased temperature following the metamorphic peak probably resulted in the formation of REE -, V- and Cr-poor clinozoisite and secondary garnet. [ABSTRACT FROM AUTHOR]

The platinum-group minerals (PGM) occur in Triassic-Jurassic metapyroxenite from allochtonous serpentinite body near Jasov village, Meliatic Unit, Inner Western Carpathians, eastern Slovakia. The PGM assemblage originated during two genetic stages. The primary magmatic stage 1, formed under very low fO2; it comprises older generation of PGM: laurite (RuS2), erlichmanite? (OsS2), sperrylite (PtAs2), iridium, and osmium. The younger generation of PGM formed during post-magmatic, hydrothermal-metamorphic stage 2, including irarsite [(Ir,Rh)AsS], hollingworthite [(Rh,Ir)AsS], possibly part of sperrylite (PtAs2), temagamite (Pd3HgTe3), vasilite-like mineral [Pd2(S,Te)], and unnamed phases of (Ir,Os)As3, (Pd,Ni)3Sb, and Pd6Ni3Sb2 (?) stoichiometry. Minerals of the magmatic stage were derived from the deep mantle source under highly reductive conditions, and the primary rock was probably transported by a plume to shallower upper mantle depth. The hydrothermal-metamorphic stage originated by partial hydratation and serpentinization of the metapyroxenite under the blueschists facies metamorphism. The Jasov metapyroxenite represents the first reported occurrence of PGM in the Western Carpathians. [ABSTRACT FROM AUTHOR]

The Cr-Ni-rich micas, Ni-Co sulphide phases and associated minerals occur in a small body of listvenite, an extensively altered serpentinite, in Lower Palaeozoic paragneisses near Muránska Zdychava village in Slovenské Rudohorie Mts. (Veporic Superunit, central Slovakia). The main rock-forming minerals of the listvenite are magnesite, dolomite and a serpentine-group mineral, less frequently calcite, quartz and talc. Accessory minerals of the listvenite include Cr-Ni--rich micas, chromite, and Ni-Co-Fe-(Cu-Pb) sulphide minerals (pyrite, pyrrhotite, pentlandite, millerite, polydymite, violarite, siegenite, gersdorffite, cobaltite, chalcopyrite and galena). The micas from the Muránska Zdychava listvenite (Cr-Ni-rich illite to muscovite and Ni-dominant trioctahedral mica) contain the highest Ni concentrations ever reported in the mica-group minerals (up to 22.8 wt. % NiO or 1.46 apfu Ni). The Cr concentrations are also relatively high (up to 11.0 wt. % Cr2O3 or 0.64 apfu). Compositional variations in both Cr-Ni-rich mica minerals are characterized by the negative Cr vs. Ni correlation that indicates a dominant role of 2OM3+ + O□ = 3OM2+ and OM3+ + TAl = OM2+ + TSi substitution mechanisms. Chromite is dominated by Fe2+ (0.82-0.90 apfu) and Cr (1.38-1.79 apfu). The listvenite contains ~0.3 wt. % Cr2O3 and ~0.2 wt. % NiO. It represents a good example of multistage transformation of an ultrabasic protolith, reflecting variable alteration. The incipient alteration leads to relatively high SiO2, MgO, and Cr2O3 contents, the latter two typical of ultrabasic rocks. The more advanced alteration stage shows lower SiO2, but higher content of volatiles (c. 35 wt. % of LOI) bound in carbonates and hydrated silicate minerals. Based on geochemical and mineralogical characteristics, the studied listvenite body originated during three principal evolutionary stages: (1) peridotite stage, (2) serpentinization stage, and (3) hydrothermal-metasomatic stage (listvenitization). The listvenite origin was probably connected with Alpine (Late Cretaceous) late-orogenic uplift of the Veporic Superunit crystalline basement and retrograde metamorphism; we assume P-T conditions of the final listvenite stage at ~200 MPa and up to 350 °C. The NE-SW and NW-SE trending fault structures played a key role during the process of listvenitization as they channelized the CO2-rich fluids that transformed the serpentinized peridotite into the carbonate-quartz listvenite. [ABSTRACT FROM AUTHOR]

Iron-titanium oxides represent significant mineral phase (≤1.5 vol. %) in the A-type rhyolites from the Silicic Superunit, Western Carpathians, central Slovakia. They are composed of magnetite, ilmenite, and rutile showing typical lamellae “trellis - sandwich” type texture as a result of oxy-exsolution of former Ti-rich magnetite. A composite type and complete decomposition of primary Ti-rich magnetite to a very fine lamellae aggregate of hematite/rutile or to the progressive C4 stage of Fe-rich rutile/hematite occurs in lesser extent. The compositional data show significant miscibility along the ilmenite– hematite join. The ulvöspinel component in magnetite reaches up to 18 mol. %, while the rutile is more uniform and close to end-member composition. However, in some cases rutile is enriched in Fe getting up to 5 wt. % FeOtotal mainly with coexisting ilmenite–hematitess. Fe–Ti oxide geothermometry yields a relatively smooth evolutional T-trend ranging from late-magmatic to subsolidus/solidus stages with equilibrium temperatures from ~750 to ~400 °C and fO2 values approaching the NiNiO buffer from -0.76 Δlog fO2 (~626 °C) to 1.53 Δlog fO2 (~655 °C). The presence of Ti-rich magnetite, Ti-poor magnetite, ilmenite to hematite, and discrete rutile in rhyolitic magma point to a long termed process from orthomagmatic to a low-temperature subsolidus/solidus stage showing a gradual decrease of oxygen fugacity. The Fe–Ti oxide investigation indicates a relatively short-term storage of the Permian A-type silicic melt at shallow depths prior to eruption. [ABSTRACT FROM AUTHOR]

Grossular garnet, enriched in Cr and V, forms rare subhedral crystals (up to 40 μm in size) with diopside, albite, K-feldspar, titanite and clinozoisite in Ca-skarn near Dubová, Malé Karpaty Mts., Western Carpathians (SW Slovakia). The skarn is situated along the contact between Devonian limestones and Carboniferous granitic rocks. Grossular crystals shows two distinct zones: Cr-V enriched core and Cr-V poor rim with sharp boundary between the zones. The Cr,V-rich grossular cores contain 0.9 to 5.3 wt. % Cr2O3 (0.06 to 0.33 apfu Cr) and 0.5 to 2.0 wt. % V2O3 (0.03 to 0.13 apfu V), whereas the rims exhibit ≥ 0.5 wt. % Cr2O3 (≥ 0.03 apfu Cr) and ≥ 0.3 wt. % V2O3 (≥ 0.02 apfu V). The garnet cores and rims show (in mol.%): 60 - 73 and 75 94 grossular, 11 - 19 and 2 - 19 andradite, 3 - 18 and 0 - 2 uvarovite, 1 - 7 and 0 - 1 goldmanite, 1 - 4 and 0 - 5 almandine, and 0.5 - 1.4 and 0.4 - 1.6 spessartine, respectively. The garnet cores usually corresponds to Cr > Mn > V (apfu) composition, a new type in chemical classification of V,Cr-rich grossular (tsavorite). Adjacent dark, graphite-rich phyllites were probably the source of Cr and V. The Cr,V-rich grossular cores precipitated probably during the early contact-metamorphic stage, whereas the Cr,V-poor rims originated during later, main evolution stage of the skarn formation. [ABSTRACT FROM AUTHOR]

Monazite-(Ce) represents a characteristic magmatic accessory mineral of the Hercynian peraluminous S-type granites to granodiorites and related granitic pegmatites of the Bratislava Granitic Massif (BGM), Malé Karpaty Mountains, Central Western Carpathians, SW Slovakia. Monazite forms euhedral to subhedral crystals, up to 200 μm in size, usually it is unzoned in BSE, rarely it reveals oscillatory or sector zoning. Thorium concentrations of 2 to 9 wt. % ThO2 (≤ 0.09 apfu) and local elevated uranium contents (≤ 4.3 wt. % UO2, ≤ 0.04 apfu) are characteristic for the pegmatite monazites. Both huttonite ThSiREE-1P-1 and cheralite Ca(Th,U)REE-2 substitutions took place in the studied monazite. Electron-microprobe Th-U-Pb monazite dating of the granites and pegmatites gave an isochron age of 353 ± 2 Ma (MSWD = 0.88, n = 290), which confirmed the meso-Hercynian, Lower Carboniferous (Mississipian) magmatic crystallization. An analogous age (359 ± 11 Ma) was obtained from monazite from adjacent paragneiss, corresponding to the age of the Hercynian contact thermal metamorphism related to the granite intrusion of BGM. Monazite in some granite shows also older clastic or authigenic grains or zones (~ 505 to 400 Ma, with maximum of 420 ± 7 Ma) which probably represents inherited material from the Lower Paleozoic metapelitic to metapsammitic protolith of BGM. [ABSTRACT FROM AUTHOR]

Abstract: The initial to advanced stage of monazite breakdown was identified in a granitic orthogneiss from the pre-Alpine basement in the Veľký Zelený Potok Valley (the Veporic Unit, Western Carpathians, central Slovakia). Monazite-(Ce) formed during Variscan metamorphism of the original Cambrian to Ordovician granitic rock. Two younger, Permian post-magmatic hydrothermal, and Cretaceous metamorphic-hydrothermal events caused a breakdown of the monazite to secondary egg-shaped coronal structures (100 to 500μm in diameter) with concentric newly-formed mineral phases. Two principal breakdown stages and newly formed mineral assemblages are recognizable: (1) partial to complete replacement of primary monazite with an internal apatite+ThSiO4 (huttonite or thorite) zone and an external allanite-(Ce) to clinozoisite zone; (2) hydroxylbastnäsite-(Ce) partly replacing apatite+ThSiO4 and allanite to clinozoisite aggregates. The monazite breakdown was initiated by fluid sources differing in composition. Stage (1) originated due to post-magmatic hydrothermal fluids, whereas stage (2) indicates an input of younger, CO2-bearing metamorphic-hydrothermal fluids. [Copyright &y& Elsevier]

Abstract: The phosphate–sulphate mineralization occurs in quartz veins in Lower Triassic metaquartzites of the Tribeč Mts., Central Western Carpathians, Slovakia. The mineralization comprises of lazulite, Ba, Sr, Ca, K-rich phosphates–sulphates and barite in an association with muscovite, hematite, locally rutile, zircon, chlorite and tourmaline. The most widespread lazulite forms up to 10 cm large pale to deep blue aggregates in massive quartz. Electron-microprobe analyses show a relatively uniform composition with Mg/(Mg+Fe)=0.85 to 0.93. The Mössbauer spectroscopy reveals 11–30% Fe3+/Fetotal. Possible primary goedkenite–bearthite binary s.s. shows the highest known Sr contents worldwide: Sr/(Sr+Ca)=0.67–0.71; Mg, Ba and REE contents are negligible. The lazulite is replaced by a secondary association of Ba, Sr, Ca, K-rich phosphates–sulphates: gorceixite, rarely goyazite, crandallite, svanbergite, jarosite and a rare phase, close to (Ba,K,Sr)(Fe3+,Al)3[(OH,H2O)6(PO4)(SO4)] composition (Ba,Fe,S,P-phase). Gorceixite exhibits more restricted compositional variations between gorceixite–goyazite and gorceixite–crandallite s.s.: Ba/(Ba+Sr)=0.73–0.99, Ba/(Ba+Ca)=0.78–0.99 and (P−1)/[(P−1)+S]=0.84–0.99. On the contrary, the secondary Sr, Ca-dominant phosphates–sulphates of the crandallite and beudantite groups show wide compositional variations and complex quarternary solid–solution series between goyazite–crandallite and svanbergite–woodhouseite with Sr/(Sr+Ca)=0.16 to 0.99 and (P−1)/[(P−1)+S]=0.07 to 0.97. The K, Ba-dominant phosphates–sulphates of the alunite and beudantite groups occur along jarosite–Ba,Fe,S,P-phase s.s. line with Ba/(Ba+K)=0.07 to 0.56, Fe/(Fe+Al)=0.55 to 0.99, P/(P+S)=0.14 to 0.57 and elevated Sr and Ca (up to 0.24 and 0.12 apfu, respectively). The compositions indicate a close relationship and mutual substitutions between the crandallite, beudantite and alunite groups. Unlike to analogous phosphate-bearing assemblages in the Alps, investigated phosphate–sulphate association doesn''t contains REE, Y and Sc minerals but it is rich in Ba-phases (barite, gorceixite). The peak metamorphic conditions of the host rocks estimated using the Kübler index of phyllosilicates point to anchizone/epizone boundary, i.e. ca. 270–350 °C. Fluid inclusions study constrained the minimum formation temperatures of the lazulite to 144–257 °C and of the superimposed sulphate–phosphate mineralization to 175–289 °C. Lazulite crystallized from brines of the system H2O–Na–Mg–Cl–CO2 with a salinity of 17.2 to 19.8 wt.% NaCl eq. We propose, that the studied mineralization originated from fluids enriched in elements from breakdown of feldspars, biotite, apatite and other phosphates in underlying Hercynian granites. The fluids passed upwards into the metaquartzites and precipitated discrete minerals, due to absence of any suitable sink for the elements among rock-forming minerals. [Copyright &y& Elsevier]

Accessory Fe-rich columbite-group minerals, tapiolite and Hf-rich zircon occur in Hercynian pegmatitic leucogranite near Duchonka, Považský Inovec Mts., western Slovakia. The host rock represents highly peraluminous and fractionated S-type pegmatitic leucogranite with ASI = 1.27, EuN/Eu*N = 0.16, Rb/Sr = 7.2, Ta/Nb = 1.1 and Zr/Hf= 21, but not enriched in Li, B, Be or P. Columbite-tantalite, tapiolite and hafnian zircon form discrete crystals, 30 to 350 μm in size, in association with quartz, plagioclase, K-feldspar, muscovite, sillimanite, almandine-spessartine and fluorapatite. Columbite-tantalite crystals show coarse oscillatory zoning, usually with border parts enriched in Ta. Locally, there is a reversal trend of zoning (decrease of Ta towards the border parts), or irregular convoluted zoning as a result of late-magmatic to subsolidus dissolution-reprecipitation. The composition of columbite-tantalite shows a relatively constant Mn/(Mn + Fe) ratio (0.20-0.27, locally 0.35-0.40), but extreme variations of the Ta/(Ta + Nb) ratio (0.18-0.72). Ratios higher than 0.63 plot inside the tantalite-tapiolite miscibility gap. Ferrotapiolite is mainly homogenous and shows relatively consistent compositions with Mn/(Mn + Fe) 0.03-0.04 and Ta/(Ta + Nb) = 0.88-0.97. Metamict zircon (5 to 120 μm in size) exhibits tiny uraninite inclusions, high Hf contents (6 to 23 wt. % HfO2, 0.06-0.23 Hf apfu), and locally elevated P, As and U contents, whereas Y and REE concentrations are low. Unusually widely variable and high Ta/Nb and Hf/Zr ratios in the accessory minerals are probably the product of extreme local Nb-Ta and Zr-Hf fractionation in highly peraluminous granite-pegmatite system. [ABSTRACT FROM AUTHOR]

Mineralization, involving vanadian-chromian silicates, has been studied in Lower Paleozoic, carbon-rich amphibole schists with pyrite and pyrrhotite near Pezinok, southwest Slovakia. A detailed electron microprobe study has revealed the presence of V,Cr-rich garnet, clinozoisite, and muscovite, associated with amphiboles (magnesiohornblende, tremolite, actinolite, and edenite), diopside, and albite. The garnet contains 5-19 wt% V2O3, 5-11 wt% Cr2O3, and 2-13 wt% Al2O3 (16-64 mol% goldmanite, 19-36 mol% uvarovite, and 9-59 mol% grossular end-members). The garnet is unzoned or shows V-rich cores and Al-rich rims, or irregular coarse oscillatory zoning with V, Cr, and Al, locally involving Ca and Mn as well. The V,Cr-rich clinozoisite to mukhinite and "chromian clinozoisite" contains 2-9.5 wt% V2O3 and 1.5-11 wt% Cr2O3; the muscovite contains 2.5-8 wt% V2O3 and 0-7 wt% Cr2O3. The mineralization originated from primarily V-, Cr-, and C-rich mafic pyroclastic rocks, affected by volcano-exhalative processes. These rocks were weakly metamorphosed during early Hercynian regional metamorphism (M1), followed by late-Hercynian contact metamorphism (M2) with crystallization of V,Cr-rich silicates, diopside, amphiboles, phlogopite, titanite, albite, quartz, carbonate, pyrite, and pyrrhotite. The youngest Alpine(?) retrograde metamorphic event (M3) is connected with production of V,Cr-poor muscovite, clinochlore, clinozoisite, pumpellyite-(Mg), prehnite, quartz, and carbonates, under prehnite-pumpellite facies conditions. [ABSTRACT FROM AUTHOR]

Abstract: A unique REE–Y–(Th)–P–As–(Si)–(Nb)–(S) accessory assemblage was identified in a small body of Lower Triassic A-type rhyolite of the Silicic Superunit near Tisovec-Rejkovo, Central Slovakia. Arsenian monazite-(Ce)–phosphatian gasparite-(Ce) and arsenian xenotime-(Y)–phosphatian chernovite-(Y) solid solutions in association with REE carbonates (bastnäsite, parisite, röntgenite?, synchysite) and rare cerianite-(Ce) form anhedral to subhedral grains and aggregates (≤0.3 mm), scattered in the groundass or as intergrowths with zircon and Fe–Ti oxides. Compositions show a wide AsP−1 substitution in monazite–gasparite and xenotime–chernovite solid solutions; atom. % As/(As+P)=0.00 to 0.73 and 0.10 to 0.94, respectively. The presence of S in monazite–gasparite s.s. (≤0.14 apfu), together with Ca enrichment indicates “clinoanhydrite“ substitution, CaS(REE,Y)−1 (P,As)−1, rather than the incorporation of brabantite, along the CaTh(REE,Y)−2 exchange vector. Moreover, the Th- and Nb-rich members reveal thorite and fergusonite substitutions, ThSi(Y,REE)−1 (P,As)−1 and Nb(P,As)−1, respectively. The As-rich REE phases originated probably during the post-magmatic alteration of primary monazite-(Ce) and xenotime-(Y) by As-rich, high fO2 fluids, whereas cerianite-(Ce) and the REE carbonates are products of a later hydrothermal overprint of the rhyolite by CO2-rich solutions. [Copyright &y& Elsevier]

Xenotime-(Gd), ideally GdPO4, is a new mineral of the xenotime group. It was discovered at the Zimná Voda REE–U–Au occurrence near Prakovce, Western Carpathians, Slovakia. It forms rare crystal domains (≤20 μm, usually ≤10 μm in size) in Gd-rich xenotime-(Y) crystals (≤100 μm in size), in association with monazite-group minerals, uraninite, fluorapatite and uranyl arsenates–phosphates. The hydrothermal REE–U–Au mineralisation occurs in a quartz–muscovite vein, hosted in Palaeozoic phyllites near exocontact with Permian granites. The density is 5.26 g/cm3, based on calculated average empirical formula and unit-cell parameters. The average chemical composition (n = 6) measured by electron microprobe is as follows (wt.%): P2O5 30.1, As2O5 0.5, SiO2 0.2, UO2 0.3, Y2O3 15.7, (La, Ce, Pr, Nd)2O3 0.5, Sm2O3 5.7, Eu2O3 1.4, Gd2O3 29.2, Tb2O3 3.9, Dy2O3 10.4, Ho2O3 0.4, (Er, Tm, Yb, Lu)2O3 2.1, (Ca, Fe, Pb, Mn, Ba)O 0.1, total 100.5. The corresponding empirical formula calculated on the basis of 4 oxygen atoms is: (Gd0.37Y0.32Dy0.13Sm0.08Tb0.05Eu0.02Er0.01Tm0.01Nd0.01...)Σ1.01(P0.98As0.01Si0.01)O4. The empirical formula of the Gd-richest composition is: (Gd0.38Y0.31Dy0.13Sm0.08Tb0.05Eu0.02Er0.01Nd0.01Ho0.01...)Σ1.01(P0.98As0.01Si0.01)O4. The ideal formula is GdPO4. The xenotime-type structure has been confirmed by micro-Raman spectroscopy and a Fast Fourier-Transform pattern using HRTEM. Xenotime-(Gd) is tetragonal, space group I 41/ amd , a = 6.9589(5) Å, c = 6.0518(6) Å, V = 293.07(3) Å3 and Z = 4. The new mineral is named as an analogue of xenotime-(Y) and xenotime-(Yb) with Gd dominant among the REE. The middle REE enrichment of xenotime-(Gd) is shared with the associated monazite-(Gd) and Gd-rich hingganite-(Y). This exotic REE signature and precipitation of Gd-bearing minerals is a product of selective complexing and enrichment in MREE in low-temperature hydrothermal fluids by alteration of uraninite, brannerite and fluorapatite on a micro-scale. The existence of xenotime-(Gd) and monazite-(Gd) is the first naturally documented dimorphism among REE phosphates. In addition, xenotime-(Gd) is only the third approved Gd-dominant mineral, after lepersonnite-(Gd) and monazite-(Gd). [ABSTRACT FROM AUTHOR]

This work is an investigation of the assemblages of supergene minerals occurring in hydrothermal REE–U–Au quartz-vein mineralisation at the Prakovce-Zimná Voda site, Slovakia. Heterogeneous uranyl arsenates and minor phosphates of the autunite group (nováčekite, kahlerite, threadgoldite, autunite, arsenuranospathite and chistyakovaite) together with scorodite and Sb–Bi-rich philipsbornite–segnitite-series minerals formed by oxidising fluids during decomposition and leaching of primary hypogene uraninite, brannerite and base-metal sulfides and sulfosalts. A progressive change of pH from acidic to near-neutral due to the gradual consumption of sulfides resulted in the formation of late phosphuranylite, pharmacosiderite and arseniosiderite. Goethite and other Fe oxides represent the latest hydrous ferric mineral phases and were formed after most of the As was already fixed in Fe arsenates. Antimony and Bi were taken up only into philipsbornite–segnitite and suggest unusual conditions during this process. X-ray absorption spectroscopy indicates that Sb in the philipsbornite–segnitite is fully oxidised (0.1–0.4 apfu Sb5+, octahedral coordination on the G site). Pentavalent Sb together with the presence of ferric oxides and arsenates and uranyl minerals suggest oxidative conditions during weathering. This study also indicates that hydrous ferric arsenates are dominant and stable secondary minerals in a supergene environment in a quartz vein rich in Fe and As accompanied by elevated concentrations of U, Pb, Sb, Bi, S, P, Ca and Ba under oxidising conditions. [ABSTRACT FROM AUTHOR]

Two contrasting reaction coronae were developed around rare earth element (REE) accessory phosphates in Variscan metagranitic rocks, which have been overprinted by Alpine blastomylonitisation from the Fabova Hol'a Massif, in the Veporic Unit, Western Carpathians, Central Slovakia. The Th–U–Pb total EPMA age determination of primary magmatic monazite-(Ce) from the metagranite indicates a Carboniferous (Mississippian, Tournaisian) age of 355 ± 1.9 Ma. Monazite-(Ce) breakdown resulted in impressive, though common, fluorapatite ± Th-silicate + allanite-(Ce) + clinozoisite coronae. The alteration of xenotime-(Y) produced a novel type of secondary coronal micro-texture consisting of a massive fluorapatite mantle zone and tiny satellite crystals of hellandite-(Y) [(Ca,REE)4Y2Al□2(B4Si4O22)(OH)2] and hingganite-(Y) [Y2□Be2Si2O8(OH)2] of ~1–5 μm, and rarely ≤10 μm in size. The localised occurrence of Y–B–Be silicates, which are associated closely with other secondary minerals, suggests the involvement of B and Be during the metasomatic alteration transformation of xenotime-(Y). General reactions for monazite-(Ce) and xenotime-(Y) decomposition, including the fluids involved, can be written as follows: Mnz + (Ca, Fe, Si, Al and F)-rich fluid → FAp + Ht + Aln + Czo; Xtm + (Ca, Fe, Si, Al, F, B and Be)-rich fluid → FAp + Hld + Hin + Czo. The granitic rocks underwent Early Cretaceous burial metamorphism under greenschist- to lower amphibolite-facies P–T conditions. Subsequently, Alpine post-collisional uplift and exhumation of the Veporic Unit, starting from the Late Cretaceous epoch, was accompanied by a retrograde tectono-metamorphic overprint; the activity of external fluids, caused the formation of secondary coronae minerals around monazite-(Ce) and xenotime-(Y). A portion of B (± Be) should have been liberated from the metagranite feldspars, micas, or xenotime-(Y) enriched in (Nb,Ta)BO4 (schiavinatoite or béhierite) components. However, the principal source of B and Be in fluids necessary for the production of hellandite and hingganite, was probably of external origin from adjacent magmatic, metamorphic, or sedimentary rocks (Permian granites, rhyolites and sedimentary rocks, and Palaeozoic metapelites). [ABSTRACT FROM AUTHOR]

The geochemical behaviour of phosphorus in granites, coupled with compositional variations in apatite, discriminate the different genetic suites of Variscan granitic rocks in the West-Carpathian orogenic belt. Meso-Variscan granites, mostly of S-type affinity, show a good correlation between SiO2 and P2O5, with decreasing amounts of P in the poorly and moderated fractionated granites, and increasing phosphorus in the most evolved and late differentiation products. The aluminium saturation index (ASI) correlates negatively with bulk P contents in I-type granites, and positively with P in S-type granites. The phosphorus content of alkali feldspar (mainly Kfs) is usually very low (typically <0.05 wt.% P2O5), or not detected in the slightly differentiated granites. In the lateVariscan I/S-type granitoids, phosphorus is hosted mainly in the early-magmatic apatite, but is present also in the late K-feldspar (up to 0.15 wt.% of P2O5) that formed from the residual melts. In the post-orogenic S-type granites, the bulk of the phosphorus occurs in alkali feldspar (∼0.3 wt.% P2O5), with a minor proportion present in primary early-magmatic apatite. Clusters of small secondary apatite grains with a distinctive composition are distributed in alkali feldspar grains of the post-orogenic S-type granites. This apatite has formed post-magmatically from P released from P-rich alkali feldspar during decreasing temperature, by reaction with a fluid rich in volatiles (including F and B), and alkali and alkali earth metals. A-type granites have the lowest bulk phosphorus contents. Consequently, phosphate minerals are relatively rare in this granite type, and the alkali feldspar has negligible P2O5 contents.Except for Sr, the minor element contents in apatite partly correlate with the bulk composition of their host rocks and partly reflect some thermodynamic properties of melt. The Mn contents of apatite increase with the peraluminous character of the melt and with decreasing fO2 and so apatite from the S-type granites has significantly higher Mn contents than apatite from the I-type granites. Apatite from A-type granites is enriched in Fe and HREE, reflecting the higher bulk Fe and HREE content of this granite type. Apatite from specialized S-type granites is enriched in Y and HREE. In general, the Cl and S content of apatite is higher in the basic members of the I-type affinity granitic rocks. [Copyright &y& Elsevier]