Cummingtonite-bearing volcanic rocks: first evidence in the Central Slovak Volcanic Field (original) (raw)
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Geological Quarterly, 2014
Biostratigraphic in ves ti ga tions of car bon ate strata that sand wich vol ca nic rocks and stud ies of the vol ca nic rocks were made along five com pos ite lithological sec tions across the Up per Jurassic-Lower Cre ta ceous car bon ate rocks of autochthonous cover of the High-Tatric Unit in the Osobitá peak area of the West ern Tatra Mts. A car bon ate microbreccia that con sists almost ex clu sively of lime stone clasts con tain ing calpionellids oc curs im me di ately be low the volcanics. The youn gest iden tified microfossil Calpionella elliptica Cadisch in the in di vid ual lime stone clasts showed the age of brec cia for ma tion to be youn ger than late Early-early Middle Berriasian. The vol ca nic rocks are over lain by the Osobitá Lime stone For ma tion, which in the low er most ho ri zons con sists of a few metres thick crinoidal lime stone con tain ing the foraminifers Meandrospira favrei (Charollais, Brönnimann and Zaninetti), Sabaudia minuta Hofker and Montsalevia salevensis (Charollais, Brönnimann and Zaninetti) in di cat ing a Late Valanginian-Early Hauterivian age. The biostratigraphical and sedimentological data ob tained show that vol ca nism took place in sev eral phases. Less in tense phases of vol ca nism are re corded as thin tuffitic laminae within the up per parts of the Tithonian-early Middle Berriasian Sobótka Lime stone Mem ber and as frag ments of vol ca nic rock in the car bon ate brec cia. The main phase(s) of vol ca nism took place dur ing the Late Berriasian-?Early Valanginian.
Geologica Carpathica, 2021
Perlites in the Central Slovakia Volcanic Field are associated with with rhyolite dykes, cryptodomes, extrusive domes, coulées and volcanoclastic rocks of the Jastrabá Fm. (12.3–11.4 Ma). From numerous occurrences only the Lehôtka pod Brehmi (LPB) and Jastrabá (JST) represent deposits of economic interest. The LPB deposit exploits a pile of extruded hyaloclastite breccia composed of grey porous and dark dense fragments. The JST deposit exploits glassy rhyolite breccia composed of grey porous fragments associated with an extrusive dome/coulée. The perlites at both deposits are peraluminous, calc-alkaline of the high-K type, poor in phenocrysts (around 5 %) of plagioclase, biotite and minor amphibole (LPB) or sanidine/anorthoclase (JST). Glass at both deposits is silica rich (75.4–79.5 wt. % dry) with Al2O3, K2O and Na2O as other major constituents. It is inhomogeneous showing domains enriched in Na2O or K2O. Glass water content (3.0–6.0 wt. %) shows a weak positive correlation with i...
Minerals
In this paper, we discuss the hypothesis on the volcanic origin of the precursor sediments for a thick (0.6 m) clay bed, hosted by the sequence of lithothamnium limestones of the Pińczów Formation. Combined X-ray powder diffraction, imaging methods (optical and electron microscopy), and chemical analysis were used to document the volcanic markers, which were preserved in the rock studied. The results obtained show that the clay bed discussed is bentonite in origin. This bentonite, which can be called Drugnia Rządowa bentonite, is composed almost entirely of montmorillonite with little admixtures of quartz and biotite. A small amount of calcite is present, but only in the top of the bed. Despite that, the bentonite contains nothing but clay material—it is a model example of entirely altered pyroclastic rock, which retains texture originally developed in volcanic glass fragments and reveals the preserved original features of the precursor fallout pyroclastic deposits (rhyolitic in cha...
Minerals, 2021
The paper presents new geochemical data of the basic to intermediate volcanic rocks from the Hronic unit. The studied rocks are strongly altered and the primary mineral composition (clinopyroxenes, amphiboles, spinels, biotites, and plagioclases) is preserved only in some localities. The clinopyroxene corresponds to augite and primary amphiboles to pargasites. Spinels have a chemical composition similar to spinels from volcanic rocks. According to chemical composition, the studied basalts correspond to rift-related continental tholeiites. 143Nd/144Nd vs. 87Sr/86Sr isotopic ratios of the basalts are scattered around the value of 143Nd/144Nd for CHUR, where 143Nd/144Nd ratios are relatively stable and 87Sr/86Sr values are relatively varied. According to isotopic ratio of 207Pb/204Pb vs. 206Pb/204Pb, the basalt analyses lie in the field of EMII (mantle source enriched with crustal materials). The new results of U-Pb LA-ICP-MS dating of apatite point to an age 254 ± 23 Ma (Lopingian).
Cenozoic C ˇ eské Středohoří volcanic complex (CSVC) of the Bohemian Massif (Czech Republic) forms the eastern part of the Central European Volcanic Province and is associated with the Ohře/Eger graben which belongs to the rift system stretching from Spain and France through Germany to the Czech Republic and Poland. CSVC is about 90 km long and up to 25 km wide. The main pulse of the magmatic activities took place from Late Eocene to Middle Miocene and peaked from 32 to 24 Ma. CSVC is composed of lava flows, volcanosedimentary deposits and subvolca-nic intrusions. The volcanic rocks are sodic (Na 2 O>K 2 O) alkaline silica-undersatu-rated types, which form two main associations: (1) basanite-phonolite and (2) subordinate trachybasalt-trachyte series, which differ particularly by the major element variations and Nd-Sr isotopic compositions. The mafic rocks strongly predominate over the felsic types (6%). The intermediate rocks are rare. Petrological modeling using MELTS software shows that both suites were generated from two distinct parental magmas (basanitic and basalt/trachybasaltic) by fractional crystallization without noticeable crustal contamination. Some phonolites, particularly their abundances of several incompatible trace elements such as heavy REE and Zr, were modified by late-to post-magmatic fluids. The compositional differences among the mafic rocks are, in part, related to variably metasomatically enriched lithospheric mantle. The Nd-Sr isotopic and trace element composition of the mafic magma indicates that the mantle source was slightly heterogeneous amphibole-and/or phlogopite-bearing garnet peridotite. The presence of garnet, amphibole and/or phlogopite indicates lithospheric melting took place close to the asthenosphere-lithosphere boundary. The lithospheric mantle source was probably metasomatically enriched by fluids or melts from an upwelling asthenospheric mantle. The enrichment may have taken place during the later stages of the Variscan orogeny. The two mafic parent magmas may be derived from a similar source which showed subtle differences in the source mineralogy mode and Nd-Sr isotopic compositions.
Volcanica, 2021
Almandine-rich garnets from a Neogene andesite of Slovakia can be divided into two main types. Garnet megacrysts are magmatic and form a chemically homogeneous group that contains, on average, about 5 wt% CaO and 4.5 wt% MgO as petrogenetically significant components. Garnets occurring in lithic fragments and garnets aggregated in garnetite lenses are characterised by Ca-poor cores (CaO <= 2 wt%) that testify for a two-step history and correspond respectively to inherited pre-anatectic and peritectic garnets. Available experimental data show that the composition of magmatic garnet megacrysts is compatible with a peritectic origin, through the fluid-absent melting of an immature metasedimentary protolith or a tonalitic gneiss. However, thermal evolution evidenced by zircons shielded in garnet rather suggests that garnet nucleated and grew by cooling of a hybrid magma pool, resulting from the complete mixing of crust- and mantle-derived melts.
GEOCHRONOLOGY OF THE NEOGENE VOLCANISM IN THE VIHORLATSKE VRCHY MOUNTAIN RANGE, EASTERN SLOVAKIA
Amphibole-pyroxene andesite extrusive domes and lava flows of the Vinné Complex, as well as the Beňatina Rhyodacite extrusive dome and Ladomirov andesite dykes show radiometric ages in the range 12.6 - 11.7 Ma, corresponding to Middle/Late Sarmatian. Overlaying basaltic andesite to pyroxene andesite stratovolcanoes show ages in the range 12.0 - 10. 0 Ma, corresponding to late Middle Sarmatian - Early Pannonian. The youngest radiometric data 9.7 and 9.4 Ma correspond to the late stage lava neck of the Vihorlat and late stage dyke of the Diel stratovolcano stratovolcano, respectively.
Evolution of monogenetic rhyolite volcanoes: Vinicky, Eastern Slovakia
2014
Four essential volcanic units have been recognized in the late Middle Miocene rhyolite complex at the southern side of the Zemplin horst next to the village Vinicky. A succession of ash/pumice flow, surge and fall deposits separated by horizons of eolian dust and paleosoil in total thickness >15 m forms the lower unit. It represents distal facies deposits of subplinian/plinian/phreatoplinian type eruptions at unidentified centers. The second unit rests upon the lower one with unconformity marking a period of erosion. It consists of coarse phreatic/phreatomagmatic pyroclastic rocks with fragments of basement rocks and glassy dacite/ rhyodacite. They represent proximal facies of a phreatomagmatic pyroclastic ring. Both units are truncated by a rhyolite extrusive dome, formed of perlite and perlitic breccias at its margin. Emplacement of the dome concluded activity of local centers northwest of Vinicky. An extensive rhyolite coulee represents the fourth, uppermost volcanic unit. It ...