Comparative mineralogical and fluid inclusion study of the Hnúst'a-Mútnik talc-magnesite and Miková-Jedl'ovec magnesite deposit (Western Carpathians, Slovakia)

Two type localities, located in two different geological and metamorphic units, have been studied. The Hnúst'a-Mútnik deposit is located in amphibolite facies rock sequences of the Veporic unit, while the Miková-Jedl'ovec deposit (a part of the Dúbrava massive) is located in greenschists facies sequences of the Gemeric unit. On both localities successive crystallisation occurred during three stages of replacement. The first two belong to an older metamorphic process M1, the third corresponds to a younger M2 metamorphic process. During the first stage dolomite1 and calcite1 has formed on the expense of protolithic limestone. The second (major) stage is characterized by crystallization of magnesite. The third stage is represented by dolomite2, talc, chlorite, pyrite. At Hnúst'a-Mútnik this stage is much better developed and is further accompanied by tremolite, phlogopite, clinozoisite, zoisite. Based on the carbonate geothermometry at Hnúst'a-Mútnik the first stage occurred at 280-400°C and the third stage at 490-540°C; at Miková-Jedl'ovec the first stage crystallized at 370-420°C. Fluid inclusion study in magnesite showed the presence of primary brine inclusions, with high concentrations of salts other than NaCl, probably highly evolved evaporated marine waters. Brines from Miková-Jedl'ovec are slightly less saline (23-24 wt% NaCl eq.) and homogenised at lower temperatures (195-248°C) than the brines from Hnúst'a-Mútnik (29-32 wt% NaCl eq., 299- 348°C). Brines are accompanied by CO 2 -rich inclusions with nearly identical parameters at both deposits (1-8 wt% NaCl eq., CO 2 density 0.53 to 0.69 g.cm -3 , Th 307 to 336°C). CO 2 fluids probably result from dissolution of carbonates and are coeval or younger than brines. At Miková-Jedl'ovec also low salinity aqueous fluid inclusions have been identified (3-8 wt% NaCl eq., Th 132-249°C), corresponding to the stage 3. Microthermometric data have been also used to determine pressure and temperature limits related to the second and partially to the third stage of replacement

In memory of Zoltán Németh (* 1962 – † 2025)

Zoltán Németh, our friend and colleague and long-standing scientific editor of Mineralia Slovaca tragically left us forever on May 4, 2025

Chemical and boron isotopic variations of tourmaline in the Hnilec granite-related hydrothermal system, Slovakia: Constraints on magmatic and metamorphic fluid evolution

Multi-stage formation of tourmaline occurs in the Hnilec granite-related hydrothermal tin mineralisation system from the Western Carpathians, Slovakia. The tourmalines belong to the schorl–dravite series and have two major stages of formation: the majority crystallized during the first stage (defined as M-stage), forming zoned tourmaline crystals with the cores being generally more Fe, Al, and Mn rich than the rims. During the second stage (defined as L-stage), tourmaline formed as small veins or irregular patches along fractures and cracks in the M-stage tourmaline grains. In the contact metapelites near the granite body, the L-stage tourmalines are more Mg-rich and Fe, Al, Mn depleted than the M-stage tourmalines. In the granites, the L-stage tourmalines have generally similar compositions to those of the M-stage tourmaline rims. The boron isotopic compositions of the M-stage tourmalines vary from ? 10.3‰ to ? 15.4‰; with no clear variation between the cores and the rims, however, some of the tourmaline grains from the contact metapelites show a slightly higher ?11B in the cores than in the rims. The L-stage tourmalines have lower ?11B value of ? 16.0‰ to ? 17.1‰. We suggest that these trends reflect a changing fluid source from a dominant magmatic–hydrothermal fluid derived from the granites to a late-stage metamorphic fluid derived from the regional metamorphism (chlorite and biotite zone) in the metapelites. The significantly higher Fe3+ in the L-stage than the M-stage tourmalines reflect changing redox conditions towards a more oxidising environment. This redox condition change may have important implications for the hydrothermal tin mineralisation in the area.<br/

Meta-igneous rocks of the West-Carpathian basement, Slovakia: indicators of Early Paleozoic extension and shortening events

Abstract The paper reviews the main West-Carpathian Early Paleozoic metamorphosed originally sedimentary-magmatic complexes, dated by SHRIMP on zircons, as indicators of crustal extension and shortening events. Igneous precursors of a Layered Amphibolite Complex (LAC) – fractionated upper mantle gabbros to diorites, dated at 503 ± 4 and 492 ± 4 Ma from the North-Veporic, or 480 ± 5 and 450 ± 6 Ma from the Tatric basement are contemporaneous with subaluminous to metaluminous I-type (507 ± 4 Ma, the South-Veporic basement), peraluminous S-type (497 ± 4 Ma, the South-Veporic basement; 516 ± 7, 485 ± 6 and 462 ± 6 Ma, the North-Veporic basement; 497 ± 6, 472 ± 6 and 450 ± 6 Ma, the Tatric basement), alkaline A-type (511 ± 6 Ma, South-Veporic basement) granitic orthogneisses and calcalkaline rhyolitic (482 ± 6 Ma) and dacitic (476 ± 7 Ma) metavolcanics (Gemeric basement), indicating a magmatic immature back arc setting. The ages point to Middle/Late Cambrian, Early and Late Ordovician magmatic phases, coeval with the extension in the northern Gondwana margin. Separation of an inferred Avalonian and/or Galatian terranes distal continental ribbon corresponds with the opening of a Medio-European Basin. A 430-390 Ma dated MP/HP metamorphic event, recorded in the LAC and associated orthogneisses, occurred in the area of thinned immature back arc basin crust due to closure of the Medio-European Basin. Thus a distal Gondwana continental ribbon north of this basin could be an eastward lateral pendant of Armorica, derived from Galatian terrane. Metaophiolites of the Pernek Group (a metagabbrodolerite dated at 371 ± 4 Ma) in the Tatric basement, analogous to island-arc tholeiites and back-arc basin basalts, indicate a back-arc basin setting north of a 430-390 Ma old northward dipping subduction/collision zone, dividing the northward drifting western Galatian terrane microplate from the Gondwana margin. Some metabasites of the Gemeric basement might indicate Late Devonian to Mississippian opening of a peri-Gondwanan Paleotethyan oceanic basin: a 383 ± 3 Ma old remelted metagabbro (482 ± 9 Ma) from the Klátov gneiss-amphibolite complex, ca. 385 Ma old porphyritic metabasite of the Zlatník ophiolite complex, as well as a 350 ± 5 Ma old HP metabasite as tectonic fragment within the Rakovec Group. The closure of Devonian-Mississippian basins, accompanied by medium-pressure (the Pernek Group) to high-pressure (blueschist to eclogitic tectonic fragments in greenschist facies rocks of the Rakovec Group) metamorphism, occurred in late Carboniferous to early Permian, when Paleotethyan realm complexes accreted to a Galatian terrane microplate, the latter represented by the older and the higher-grade Tatric and Veporic basement complexes.</jats:p

Preliminary results of the Slovakian national project regarding carbon dioxide storage in underground spaces

AbstractThe Slovak republic territory in spite of its extremely complicated geological pattern affords some possibilities for potential storage of carbon dioxide. The aim of the Slovakian National project “Quantitative parameters selected geological structures suitable for CO2 storage” is to find convenient places for this purpose in regional aquifers, and depleted hydrocarbon deposits. Besides, of these geological rock complexes–mostly ultramafic rocks - have been investigated for purposes of mineral carbonation of CO2. The first attempt about fate of CO2 in brine (regional aquifer) has been modelled from geochemical point of view.. From the preliminary results of the all above - mentioned options is obvious that for the process of the practical activation of CCS technologies many collisions with hydrogeological, geothermal and land use planning activities and regulations will be necessary to solve