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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.

Perovskite (Prv) was discovered in an abyssal harzburgite from a “mélange” type blueschist-bearing accretionary wedge of the Western Carpathians (Meliata Unit, Slovakia). Perovskite-1 formation in serpentinized orthopyroxene may be simplified by the mass-balance reaction: Ca2Si2O6 (Ca-pyroxene-member)+2Fe2TiO4 (ulvöspinel molecule in spinel)+2H2O+O2=2CaTiO3 (Prv)+2SiO2+4FeOOH (goethite). Perovskite-2 occurs in a chlorite-rich blackwall zone separating serpentinite and rodingite veins, and in rodingite veins alone. The bulk-rock trace-element patterns suggest negligible differences from visually and microscopically less (“core”) to strongly serpentinized harzburgite due to serpentinization and rodingitization: an enrichment in LREE(La,Ce), Cs, ±Ba, U, Nb, Pb, As, Sb, ±Nd and Li in comparison with HREE, Rb and Sr. The U/Pb perovskite ages at ~135 Ma are interpreted to record the interaction of metamorphic fluids with harzburgite blocks in the Neotethyan Meliatic accretionary wedge. Our LA-ICP-MS mineral study provides a complex view on trace element behaviour during the two stages of rodingitization connected with Prv genesis. The positive anomalies of Cs, U, Ta, Pb, As, Sb, Pr and Nd in Cpx, Opx and Ol are combined with the negative anomalies of Rb, Ba, Th, Nb and Sr in these minerals. The similar positive anomalies of Cs, U, Ta, ±Be, As, Sb found in typical serpentinization and rodingitization minerals, with variable contents of La, Ce and Nd, and negative anomalies of Rb, Ba, Th, Nb and Sr suggest involvement of crustal fluids during MP-LP/LT accretionary wedge metamorphism. LA-ICP-MS study revealed strong depletion in LREE from Prv-1 to Prv-2, and a typically negative Eu (and Ti) anomaly for Prv-1, while a positive Eu (and Ti) anomaly for Prv-2. Our multi-element diagram depicts enrichment in U, Nb, La, Ce, As, Sb, Pr, Nd and decreased Rb, Ba, Th, Ta, Pb, Sr, Zr in both Prv generations. In general, both Prv generations are very close to the end-member composition. In spite of low concentrations of isomorphic constituents, Prv-1 and Prv-2 display the A(La,Ce)3++B(Fe,Cr)3+=ACa2++BTi4+ heterovalent couple substitution. A decrease of ferric iron in Prv-2 indicates increasing reduction conditions during rodingitization.

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.

Various chrysoberyl varieties (non‐phenomenal chrysoberyl, alexandrite and cymophane) are gemstones of high demand; therefore, they are subjected to numerous substitutions by other materials and synthetic analogues. To address this issue, non‐destructive methods for studying gemstones are highly sought after. Raman spectroscopy is one of the most suitable non‐destructive methods for studying gemstones as it requires no sample preparation and does not leave any price‐reducing signs on the gemstone surface. The research is focused on Raman spectroscopy application on chrysoberyl identification, differentiation between its varieties, inclusion analysis, and detection of synthetic analogues and imitations. The alexandrite variety can be identified by its broad luminescence band that ranges from 640 to 790 nm (15 625–12 658 cm−1). Synthetic alexandrite has sharper and more intensive bands on the luminescence spectrum, especially 690 and 696 nm (14 492–14 367 cm−1). Rutile inclusions can be distinguished by a broad band 580–640 cm−1 in the Raman spectrum. Imitations of chrysoberyl represented by corundum and colour‐changing spessartine was also identified. The orientation of faceted stones can also be determined by specific bands present in the Raman spectrum. [ABSTRACT FROM AUTHOR]

The Maršíkov–Schinderhübel III pegmatite in the Hrubý Jeseník Mountains, Silesian Domain, Czech Republic, is a classic example of chrysoberyl-bearing LCT granitic pegmatite of beryl–columbite subtype. This thin pegmatite dyke, (up to 1 m in thickness in biotite– amphibole gneiss is characterised by symmetrical internal zoning. Tabular and prismatic chrysoberyl crystals (≤3 cm) occur typically in the intermediate albite-rich unit and rarely in the quartz core. Chrysoberyl microtextures are quite complex; their crystals are irregularly patchy, concentric or fine oscillatory zoned with large variations in Fe content (1.1–5.3 wt.% Fe2O3; ≤0.09 apfu). Chrysoberyl compositions reveal dominant Fe3+ = Al3+ and minor Fe2+ + Ti4+ = 2(Al, Fe)3+ substitution mechanisms in the octahedral sites. Tin, Ga, and V (determined by LA-ICP-MS) are characteristic trace elements incorporated in the chrysoberyl structure, whereas anomalously high Ta and Nb concentrations (thousands ppm) in chrysoberyl are probably caused by nano- to micro-inclusions of Nb–Ta oxide minerals; especially columbite–tantalite. Textural relationships between associated minerals, distinct schistosity of the pegmatite parallel to the host gneiss foliation and fragmentation of the pegmatite body into blocks as a result of superimposed stress are clear evidence for deformation and metamorphic overprinting of the pegmatite. Primary magmatic beryl, albite and muscovite were transformed to chrysoberyl, fibrolitic sillimanite, secondary quartz and muscovite during a high-temperature (∼600°C) and medium-pressure (∼250–500 MPa) prograde metamorphic stage under amphibolite-facies conditions. A subsequent retrograde, low-temperature (∼200–500°C) and pressure (≤250 MPa) metamorphic stage resulted in the local alteration of chrysoberyl to secondary Fe,Na-rich beryl, euclase, bertrandite and late muscovite. [ABSTRACT FROM AUTHOR]

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]

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% [V.sub.2][O.sub.3], 5-11 wt% [Cr.sub.2][O.sub.3], and 2-13 wt% [Al.sub.2][O.sub.3] (16-64 mol% goldmanite, 19-36 tool% 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% [V.sub.2][O.sub.3] and 1.5-11 wt% [Cr.sub.2] [O.sub.3]; the muscovite contains 2.5-8 wt% [V.su.2][O.sub.3] and 0-7 wt% [Cr.sub.2][O.sub.3]. 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,Cropoor muscovite, clinochlore, clinozoisite, pumpellyite-(Mg), prehnite, quartz, and carbonates, under prehnite-pumpellite facies conditions. Keywords: V and Cr mineralization, amphibole schists, contact metamorphism, goldmanite, uvarovite, mukhinite, Western Carpathians, Slovakia

This contribution presents research results on the stable acoustic microclimate of a classroom and ventilation system design. The authors investigated the acoustic parameters of the classroom during a long-term operation of a forced ventilation system with variable airflow. By conducting an acoustic and energy study, the energy significance of variable airflow forced ventilation is demonstrated, leading to substantial energy savings relative to the widely used constant airflow ventilation systems. The calculations show the necessity to implement specific acoustic measures to maintain an optimal acoustic microclimate in the classroom. A significant finding is the clear benefit of combining building acoustic measures with variable air volume forced ventilation systems. As shown by simulations and calculations, the use of the presented building acoustic measures can ensure a stable indoor environment in the classroom even when a forced ventilation system containing specific control elements is installed, and at the same time, reduce the energy consumption of the ventilation system by 15–20 % compared to constant airflow ventilation systems. [Display omitted] • Stable acoustic microclimate of a classroom on the design of the ventilation system. • An acoustic and energy study to achieve the microclimate at minimum energy. • High energy significance of variable airflow forced ventilation system design. • Combining acoustic measures with a variable air volume forced ventilation system. • Energy savings 15–20 % compared to constant airflow ventilation systems. [ABSTRACT FROM AUTHOR]