Ondrej Nemec

Ondrej Nemec
Comenius University Bratislava · Department of Mineralogy Petrology and Economic Geology

PhD.

About

31
Publications
6,350
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77
Citations
Citations since 2017
28 Research Items
77 Citations
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201720182019202020212022202305101520

Publications

Publications (31)
Conference Paper
Full-text available
The products of Miocene volcanic activity in the Slovenský Raj Mts., Middle Slovakia, are in the Lesnica Valley located SE of Čingov. Magmatic rocks comprise a volcanic intrusive complex represented by a swarm of feeder dikes and sporadic relics of hyaloclastite lavas. They intruded a complex of the Triassic Bodvaszilas sandstones and carbonates of...
Article
Full-text available
Basaltic rocks from ophiolitic mélanges provide information on geodynamic setting, origin, and later tectonometamorphic conditions. This paper resolves the P–T conditions and timing of high-pressure metamorphism in an accretionary wedge that formed during the Late Jurassic closure of the Neotethyan Meliata Basin. Blueschist-facies metabasites of th...
Conference Paper
The Ozren ophiolite complex (OOC) in Bosnia and Herzegovina is a part of large Dinaride ophiolite belt (Babajić, 2019, and reference therein). This contribution comprises mineralogical-petrographical descriptions of representative rocks of the OOC, which we sampled during the field investigation: lherzolites, harzburgites, dunites, gabbros, dolerit...
Article
Full-text available
The Dinaride Ophiolite Belt formed from the Jurassic part of the Neotethys. The investigated Ozren ophiolite complex in Bosnia and Herzegovina consists of peridotites, plagioclase peri-dotites, plagiogranites, troctolites and other gabbroic rocks, and fewer basalts. Lherzolites and harzburgites contain corroded ortho- and clinopyroxene1 porphyrocla...
Article
Full-text available
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 yi...
Article
Full-text available
The composite Albian–Eocene orogenic wedge of the northern part of the Inner Western Carpathians (IWC) comprises the European Variscan basement with the Upper Carboniferous–Triassic cover and the Jurassic to Upper Cretaceous sedimentary successions of a large oceanic–continental Atlantic (Alpine) Tethys basin system. This paper presents an updated...
Article
Full-text available
The paper presents whole rock chemical composition and Sr-Nd isotope data from selected metabasic rocks from the Mississippian and Pennsylvanian sequences of the Northern Gemeric Unit. The analysed metabasic rocks belong to the subalkaline magmatic series with Nb/Y ratios ranging from 0.03 to 0.21. They fit into the low-Ti tholeiitic series, charac...
Article
Full-text available
Metamorphic evolution of an accretionary wedge can be constrained by a reconstructed P-T conditions of the oceanic and continental margin fragments. This paper deals with the metamorphic overprinting of the Inner Western Carpathians (IWC) Meliatic Triassic-Jurassic paleotectonic units after the closure of the Neotethyan Meliata Basin. Medium to hig...
Chapter
Full-text available
Soták, J.; Li, Q.-L.; Ondrejka, M.; Li, X.-H.; Hu, Z.; Ling, X.; Nemec, O.; Németh, Z.; Ružička, P. Origin and Age Determination of the Neotethys Meliata Basin Ophiolite Fragments in the Late Jurassic-Early Cretaceous Accretionary Wedge Mélange (Inner Western Carpathians, Slovakia). This study reports the Neotethyan Meliata Basin ophiolite fragment...
Article
Full-text available
In the online published article, the name of one of the co-authors Katarína Šarinová was incorrectly published as Katarina Paranoia. The correct name is given below.
Article
U–Pb ages of zircons recovered from Pliocene pyroclastic deposits in northern part of the Cenozoic intra-Carpathian back-arc basin (Pannonian Basin) span the interval from Pliocene (2.2 Ma) to Paleoproterozoic (Orosirian–Rhyacian, 1850–2115 Ma). The scattered U–Pb ages reflect eruption ages of the host basaltic volcanic centres, two episodes of pos...
Article
Full-text available
This study reports the Neotethyan Meliata Basin ophiolite fragments in the Late Jurassic-Early Cretaceous accretionary wedge mélange in the southern part of the Inner Western Carpathians (IWC). Here we present new lithostratigraphical, petrographical, geochemical, and geochronological data obtained from the mélange blocks used to reconstruct the Me...
Conference Paper
Full-text available
This contribution reviews published and our new geochronological data on the Permian-Triassic tectono-magmatic events determined from the researched areas of the Slovak Inner Western Carpathians (IWC) and the Austrian Austroalpine (AA) units by zircon U-Pb SIMS. Most of the dated rocks bear the signatures of the superimposed Late Jurassic and/or Cr...
Article
Full-text available
Putiš, M., Danišík, M., Siman, P., Nemec, O., Tomek, Č., Ružička, P., 2019. Cretaceous and Eocene tectono-thermal events determined in the Inner Western Carpathians orogenic front Infratatricum. Geological Quarterly, 63 (2): 248-274, doi: 10.7306/gq.1458. This paper re-assesses the tectono-thermal evolution of the frontal Infratatricum part of the...
Article
Abstract Websterite and garnet orthopyroxenite and clinopyroxenite dykes crosscutting harzburgite occur in the hanging wall of a Cretaceous eclogitized continental fragment of the Upper Austroalpine Unit in the Eastern Alps. The dyke textures reflect pressure–temperature changes from the mantle, subduction channel and an accretionary wedge. A clino...
Conference Paper
Full-text available
The south-vergent Variscan basement structure was recognized in the higher-grade complexes of the Cretaceous Tatric and Veporic units of the Inner Western Carpathians (Putiš, 1992). The Variscan Upper Unit gneisses, amphibolites, eclogites and serpentinites, with meso-Variscan granites, were thrust over the Variscan Middle Unit micaschists at ca. 3...
Poster
Full-text available
The south-vergent Variscan basement structure was recognized in the highergrade complexes of the Cretaceous Tatric and Veporic units of the Inner Western Carpathians (Putiš, 1992). The Variscan Upper Unit gneisses, amphibolites, eclogites and serpentinites, with meso-Variscan granites, were thrust over the Variscan Middle Unit micaschists at ca. 35...
Article
Full-text available
Detrital garnets and rutiles have been recovered from basaltic pyroclastic rocks in the northern part of the Pannonian Basin and characterized using electron probe microanalysis and imaging. All garnets are dominated by the almandine component, except for one sample dominated by spessartine. A total of three garnet groups have been distinguished ac...
Conference Paper
Full-text available
The Eoalpine orogeny segments are characteristic in Alcapia, Tisia, Dacia and Adria microplates (Schmid et al., 2004, 2008; Handy et al., 2010). The Eoalpine events were dated in the Slavonian Mts. (115–110/80 Ma; Balen et al., 2017), Apuseni Mts. (125–100/80 Ma; Dallmeyer et al., 1996, 1999; Reiser et al., 2016), Western Carpathians (135–100/70 Ma...
Conference Paper
Full-text available
107 Exsolution, corona and symplectite textures of Permian pyroxenite dykes in harzburgite (Austroalpine unit, Eastern Alps): P􀂱T estimates from a subducted mantle fragment 1Putiš, M., 2Li, X.-H., 1Nemec, O., 3Balen, D., 4Koller, F., 1Hrvanović, S. 1Department of Mineralogy and Petrology, Faculty of Natural Sciences, Comenius University, Ilkovičova...
Poster
Full-text available
Websteritic and rare garnet orthopyroxenite and clinopyroxenite dykes, crosscutting a harzburgite, were dated at 252±2.4 Ma on zircon (a clinopyroxenite dyke, s. ST-8; U/Pb SIMS). This kilometre-size mantle fragment is associated with the HP metamorphosed continental crust fragment of an Austroalpine (Sieggraben) structural complex (Putiš et al., 2...
Conference Paper
Full-text available
Abstract The Austroalpine eclogitic Sieggraben structural complex forms isolated tectonic slices overlying the Lower Austroalpine Grobgneis unit along the eastern margin of the Eastern Alps. It represents a Variscan basement that underwent Cretaceous eclogite-facies metamorphism (Putiš et al., 2002, and references), now composed of mafic eclogites,...
Article
Full-text available
Peralkaline, Si-oversaturated, Al-depleted (sodium metasilicate-normative) granite xenoliths in Pleistocene alkali basalts of the Carpathian back-arc basin (Pannonian Basin) represent a new type of igneous rocks in Western Carpathians. Investigated granites contain skeletal K-feldspars associated with quartz, pyroxene, amphibole and fluorapatite. N...
Conference Paper
Full-text available
Garnet-bearing exsolution lamellae, symplectites and coronas were found in clinopyroxenite dikes crosscutting a harzburgite. These various break-down textures formed in original magmatic high-tschermakite clinopyroxenes due to eclogite-facies metamorphism.
Article
Full-text available
Products of alkaline basaltic volcanism extend from the Lučenec Basin and Cerová Highland to the northern Hungary. Volcanic activity in this area has created a large number of volcanic forms. This paper describes apatite from heavy mineral assemblages recovered from volcanoclastic fillings of maars and diatremes. Euhedral to subhedral crystal fragm...

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Projects

Projects (2)
Project
Project deals with identification of riftogenic zones in the area of the Western Carpathians and the neighbouring areas. It includes a longer time period from Late Proterozoic (at ca. 550 Ma) up to Mesozoic-Cenozoic boundary (at ca. 60 Ma), when riftogenesis continued with the opening of the main Tethyan oceans on the Earth. These preliminarily determined riftogenic zones will be investigated from the viewpoint of a long-term periodicity, intensity of magmatism, metamorphism and chemical elements mobility (recycling) between the crustal and mantle rocks: Late Proterozoic – Cambrian, Devonian, Permian – Triassic and Jurassic – Cretaceous. Specific groups of rocks and their minerals will be searched as indicators of the riftogenic zones, despite they often have signatures of superimposed tectono-thermal overprinting from their incorporation into the orogenic zones. Mineralogicalpetrological (EPMA, micro-Raman, LA-ICP-MS, XRF, ICP-MS), isotopic-geochemical (LA-MC-ICP-MS, TIMS) and geochronological (U-Pb SIMS, LA-ICP-MS, Ar-Ar, K-Ar) methods will be applied to establish the chemical composition of minerals and rocks, their isotopic characteristics (U-Pb, Pb-Pb, Sm-Nd, Rb-Sr, Zr-Hf, Re-Os) and the ages. Geothermobarometry and thermodynamic modeling with Melts, Perple_X and Thermocalc software will be used for estimation of P-T conditions of the crustal and mantle rocks mineral parageneses formation. This database can reveal the rocks origin and their magmatic and metamorphic evolution stages. We will suggest interpretation models addressed to paleotectonic zones of riftogenesis defined with typical rock associations and their mineralogical-petrological, geochemical and geochronological characteristics. Classification of riftogenic zones and their relationship to the opening of the Tethyan oceans will be confronted with published hypothetical models of riftogenesis as the domains of crust-mantle interaction and recycling, often with a significant economic potential.
Project
Project deals with fluid-alteration processes in crust-mantle prism rocks exposed in alpidic orogene of the Western Carpathians, eastern Alps and northern Turkey. These processes are related to important magmatic and metamorphic events which we studied in previous projects. Now we are focussing on fluid-rock interaction zones, the genesis of which has not yet been investigated: i) in subduction-accretionary wedges blueschists, eclogites and metaultramafics, ii) in lower crust orthogneisses, granites, metabasites and metaultramafics, iii) in skarns and iv) in lamprophyres and mantle xenoliths. These processes represent a fluid-rock interaction at the different lithosphere levels. The emphasis will be given to the newly-found mineral parageneses and individual phases, which can be basis for an updated petrologic model of crust-mantle interaction. Detailed mineralogical- petrological investigation will be performed on the altered rocks mineral associations, which are the main indicators of the lithosphere fluid regime. Modern microscopic, electron-optic, rtg diffraction and spectroscopic methods will be used for determination of the alteration zones mineral and rock chemical compositions. Thermodynamic modelling and geothermobarometry will be applied for estimation alteration reactions P-T-X conditions. Chosen radiogenic and stable isotopes, and isotopic ages of alteration products will be determined. Potential sources of fluids will be defined accordingly. Model schemes of hydration-alteration processes will be proposed in microscale, with the aim to use them for geodynamic interpretation of an orogene accretionary wedge fluid regime.