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Provenance of Albian to Cenomanian exotics-bearing turbidites in the Western Carpathians : a heavy mineral analysis

Aubrecht Roman, Bellová Simona, Mikuš Tomáš

Geological Quarterly

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2020

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Vol. 64, No. 3

658--680

EN

Throughout the Cretaceous, Tethyan oceanic branches gradually closed, and various ophiolites became obducted and eroded. Their remnants, however, provide an abundance of exotic clasts of unknown origin. Sandstone samples from the oldest, Albian exotics-bearing strata of the Pieniny Klippen Belt and Central Western Carpathians were analysed for heavy minerals. These samples were dominated by a high content of chrome-spinels, zircon, tourmaline, apatite and rutile. Titanite, kyanite, monazite, epidote, sillimanite and staurolite were much less abundant. Garnet was generally also rare; however, it was locally common, as were blue amphiboles, pyroxenes and kyanite. The spinels found in the samples were predominantly derived from harzburgites (supra-subduction peridotites and volcanic rocks). The blue amphiboles represented glaucophanes to ferroglaucophanes, and were derived from HP/LT metabasites. Pyroxenes (enstatite, less commonly augite and diopside) most likely came from coeval volcanics. Most of the tourmalines were derived from metasedimentary rocks and locally from granitoids. Furthermore, some have a complex zonation with two phases of tourmaline, or tourmaline intergrown with quartz. These were likely derived from ophiolitic sources. The results from our analysis indicate a dominance of ophiolites and older sediments with local input of continental crust metamorphic rocks. A resulting palaeogeographic reconstruction involves secondary doubling of the Neotethys suture zone and its lateral shift north of the Central Western Carpathians, which formed a common source for exotics in the Pieniny Klippen Belt and the Central Western Carpathians.

2

Skorupa oceaniczna i ofiolity w Sudetach Środkowych w świetle rozważań tektonicznych

Cymerman Z.

Przegląd Geologiczny

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2017

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Vol. 65, nr 12

1540--1547

EN

Znosko (1981a, b) first stated the important fact that the Sowie Góry "nappe” was lying on the rocks of the Middle Sudetic Ophiolite Complex. In the light of current geophysical and tectonic data, it still remains up-to-date. Both those articles have initiated a new look at the Paleozoic tectonic evolution of the Sudetes and its surroundings. This article presents an analysis ofpotential boundaries oflithostratigraphic terranes in the Sudetes and the Fore-Sudetic Block, confirmed by the waveforms of gravity horizontal gradients. Gravimetric modelling along the selected profile 3 makes it possible to present the subsurface geological structure. Metamorphic rocks of the Sowie Góry complex can probably reach a depth of almost 5 km on the Fore-Sudetic Block. Below them are mafic and ultramafic rocks, reaching a depth of up to 12 km, which belong to the Middle-Sudetic Ophiolite Complex. The kinematic data from the Sowie Góry metamorphic complex indicate displacement with the top-to-SW and to-S, as in the Middle-Sudetic Ophiolite Complex. Controversy over the origin and the geotectonic environment of the Early Ordovician protolith of the Sowie Góry gneisses, which are probably a magma product of arc-type magmatism formed above a subduction zone of the Tornquist Ocean. The Sowie Góry terrane can be considered as a relic of the Early Ordovician Paleozoic magma arc (the so-called peri-Baltic arc). The Sowie Góry terrane was moved towards the SW and S on obducted dismembered fragments of ophiolite sequences after closing the Rheic Ocean during the Eo-Variscan orogenesis.

3

Early Carboniferous (~337 Ma) granite intrusion in Devonian (~400 Ma) ophiolite of the Central-European Variscides

Kryza R.

Geological Quarterly

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2011

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Vol. 55, No. 3

213-222

EN

The Central-Sudetic ophiolites comprise mafic-ultramafic complexes around the E and S edges of the Góry Sowie Massif in SW Poland and are recognized as fragments of Devonian (~400 Ma old) oceanic crust. They contain small rodingite bodies and tectonized granite dykes that potentially can highlight the igneous, metamorphic and structural development of the ophiolitic suites. The granite dykes have been tentatively correlated with the Variscan granitoids of the Strzegom-Sobótka Massif to the north. However, new U-Pb SHRIMP zircon data for granites from the serpentinite quarry at Jordanów show a concordia age of 337 š4 Ma for the main zircon population, and of 386 š10 Ma for minor inheritance. Thus, the age of the granite is considerably older than the ages of the Strzegom-Sobótka granitoids, dated at ~310-294 Ma. The granite dyke has a similar age as some other granitoids found near the ophiolitic fragments, e.g., the Niemcza granitoids to the south, dated at 338 +2/-3 Ma; these older granitoids all represents a relatively early stage of granitoid magmatism recorded in that part of the Variscan Orogen. The age of the granitoid dyke within serpentinites confirms that the Paleozoic ophiolites were incorporated into the continental crust already in early Visean times.

4

Geochemical peculiarities of basalts of the Trostyanets volcanogenic complex (Ukrainian Carpathians)

Stupka O., Bondar R., Poberezhskyy A.

Biuletyn Państwowego Instytutu Geologicznego

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2011

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nr 444

187--190

EN

Studies of magmatic rocks of the Triassic–Lower Cretaceous ophiolite association are of great significance for geodynamic reconstructions of the evolution of the Ukrainian Carpathians. These are almond-stone basalts, clasto-lavas of basalts, and dykes of trachytes in the complex of volcanic rocks of the Trostyanets Stream. Rocks are allochthonous and hence studies of their petrochemical and geochemical properties are of great importance. Volcanites belong to the K-Na series of rocks poor in ferrimagnesian and rich in lithophylic elements; they developed on the ensialic substratum. Results of studies of two-phase fluid inclusions in calcite indicate that the gas phase constitutes 10 to 25 vol. % and is represented by CH4 and its homologues – C2H6, C3H8 and C4H10. These data may indicate a possible formation of carbon and hydrocarbons by means of the Fischer-Tropsch reaction of hydrocarbon synthesis.

PL

Badania skał magmowych asocjacji ofiolitowej triasu–kredy dolnej mają duże znaczenie dla geodynamicznej rekonstrukcji ewolucji ukraińskich Karpat. Dotyczy to bazaltów migdałowcowych, law z klastami i dajek trachitowych w kompleksie skał wulkanicznych potoku Trostyanets. Skały są allochtoniczne, toteż bardzo ważne jest badanie ich właściwości petrochemicznych i geochemicznych. Wulkanity należą do serii skał K-Na ubogich w pierwiastki żelazo-magnezowe i litofilne; tworzyły się w podwarstwie ensialicznej. Badania dwufazowych inkluzji w kalcycie pokazały, że faza gazowa zajmuje od 10 do 25% obj. i jest reprezentowana przez CH4 i jego homologi – C2H6, C3H8 oraz C4H10. Dane te mogą wskazywać na możliwość tworzenia węgla i węglowodorów na drodze reakcji Fischer-Tropscha syntezy węglowodorów.

5

The Sudetic geological mosaic : Insights into the root of the Variscan orogen

Kryza R., Mazur S., Oberc-Dziedzic T.

Przegląd Geologiczny

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2004

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Vol. 52, nr 8/2

761-773

EN

The Sudetes in the NE part of the Bohemian Massif stretch between the NW–SE-trending Odra Fault Zone and Elbe Fault Zone and represent a structural mosaic which was shaped, predominantly, during the Variscan orogeny. They are composed of various geological units, including basement units in which Neoproterozoic to Carboniferous rocks are exposed, and a post-orogenic cover of younger deposits. During the long history of geological research, the Sudetes have become a “type locality” for a range of important geological phenomena, such as granites and orthogneisses, ophiolites and (meta)volcanic sequences, granulites, eclogites and blueschists, nappe tectonics and terrane concepts. In spite of significant recent achievements, many key problems need further study, and a selection of them is proposed in this paper: (a) the presence of older, Neoproterozoic (Cadomian) rocks and their position within the Variscan collage, (b) the character and emplacement setting of Palaeozoic, pre-Variscan sedimentary successions and magmatic complexes (including ophiolites), (c) structural evolution, metamorphism (in particular HP/T grades) and exhumation of deeper crustal blocks during the Variscan orogeny, and (d) post-orogenic development. Future investigations would require an interdisciplinary approach, combining various geological disciplines: structural geology, petrology, geochemistry, geophysics and geochronology, and, also, multilateral interlaboratory cooperation.

6

Uwagi na temat genezy mineralizacji rudnej na tle ewolucji skał zespołów ofiolitowych Ślęży i Nowej Rudy : badania izotopowe tlenu

Szynkiewicz A. A., Weber-Weller A., Jędrysek M. O.

Przegląd Geologiczny

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2002

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Vol. 50, nr 1

33-41

PL

Analizy izotopowe tlenu wykonano w tlenkach (ilmenit, ilmeno-magnetyt, magnetyt), krzemianach (plagioklazy) oraz w próbkach całych skał ofiolitów Ślęży i Nowej Rudy. Badania przeprowadzono, w Pracowni Geologii Izotopowej i Geoekologii, przy zastosowaniu laserowej aparatury próżniowej do preparatyki izotopowej tlenu w mikroobszarze. Temperatury krystalizacji gabr ze Ślęży, wyznaczone w oparciu o skład izotopowy tlenu w ilmenicie, magnetycie i plagioklazach, wykazały wartości wyższe niż te powszechnie przyjmowane. Odpowiedzialny był za to proces albityzacji i saussurytyzacji plagioglazów w czasie metamorfizmu dna morskiego, który spowodował zubożenie tych minerałów w izotop*18O i przesunięcie 18O w kierunku niższych wartości o co najmniej 1,5-2o/oo. Temperatury krystalizacji skał masywu Nowej Rudy, obliczone w oparciu o *18O minerałów rudnych i całej skały, mieszczą się w szerokim przedziale, od 418 do 930oC, i są zgodne z kierunkiem zmiany sekwencji skalnych w strukturze ofiolitu. Temperatura krystalizacji skał noworudzkich malała wraz ze zbliżaniem się ku stropowym partiom ofiolitu. Na obecnym etapie badań genezę mineralizacji rudnej obu masywów należy interpretować w głównej mierze jako pierwotną magmową.Charakter zróżnicowania wartości *18O i )18O w skałach obu badanych zespołów ofiolitowych pozwala sądzić, że zupełnie inne zjawiska towarzyszyły ich tworzeniu się i ewolucji. Stąd, autorzy sugerują, że przy rekonstrukcjach geotektonicznych pojawienie się tych zespołów skalnych w ich obecnej pozycji powinno być rozpatrywane w osobnych kategoriach.

EN

The oxygen isotope analyses of oxide (ilmenite, ilmeno-magnetite, magnetite), silicate (plagioclases) and whole rock samples from Ślęża and Nowa Ruda ophiolites were carried out. The laser fluorination technique for oxygen isotope preparation of silicates and oxides was applied (Laboratory of Isotope Geology and Geoecology). The temperatures of crystallization in the Ślęża gab-bro, derived from oxygen isotope analysis in ilmenite, magnetite and plagioclase show higher values than those generally accepted. The authors believe that the processes of albitization and saussuritization of plagioclase, caused by ocean floor metamorphism resulted in^18 O-depletion of plagioclase (hence shifted the delta^18 Opl by about 1,5-2%o toward lower values). The crystallization temperatures of the Nowa Ruda ophiolite rocks, determined from the delta^18 values of ore minerals and bulk rock, varied from 418 to 930°C. These results are in agreement with the ophiolitic sequence, i.e. the temperature crystallization of the Nowa Ruda rocks decreased toward the ophiolite roof. . Thus, the authors suggest that in any new geotectonic model, the early evolution and emplacement of these ophiolites should be considered in separate terms.

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The ophiolites (serpentinites) as hydrocarbon bearers on the Zrenjanin North structure

Knezevic D., Knezevic S., Dinic B., Martinovic S.

Biuletyn Państwowego Instytutu Geologicznego

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2001

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nr 396

78-79