U-Pb dating (SHRIMP) of magmatic zircons from the Northern Veporicum Permian volcanics of the Ľubietová Group yielded concordia ages of 273 ± 6 Ma and 279 ± 4 Ma. Both zircon ages correspond to the Cisuralian Epoch in the time span of Kungurian Stage. The 272 ± 4 Ma U-Pb zircon age, determined on the volcanic dyke cutting the neighbouring crystalline basement, belongs to the same stratigraphic range. The acquired age data support a contemporaneous origin of the Permian sedimentary basin with the volcanic event and the dyke formation in the crystalline basement. Based on the whole-rock geochemical composition, the studied volcanic rocks correspond to weakly alkaline suite (trachyandesite to rhyolite/dacite). They exhibit light rare earth elements enrichment (La N /Yb N = 9.5-17.7) and small negative or absent Eu anomalies (Eu/Eu* = 0.95 and 1.05 for the Permian volcanites and 0.73 for the volcanic dyke). Characteristic of these volcanites is the enrichment in Cs, Rb, Th, U, K and Pb and the depletion in Nb, Ta, Sr and Ti if compared with average primitive mantle composition. All the studied volcanic rocks have low Nb/Ta (0.29-0.38) and Nb/U (4.07 to 5.87) ratios, implying a crustal magmatic source. Based on the incompatible trace elements Ta, Th and Yb, the Permian volcanics as well as the volcanic dyke cutting the crystalline basement fall close to the boundary between active continental margin and the within-plate fields. The 358 ± 4 Ma magmatic zircon concordia age confirmed the Early Mississippian (Tournaisian) intrusion of the metatonalites in the Volchovo Valley, later blastomylonitized and covered by Permian siliciclastics.

The Danube Basin is situated between the Eastern Alps, Central Western Carpathians and Transdanubian Range. The northwestern embayment of the basin is represented by the Blatné depression with deposits ranked into the Langhian-Serravallian (Badenian, Sarmatian) and Tortonian-Pliocene (Pannonian-Pliocene). They are documented by the NN4, NN5 and NN6 calcareous nannoplankton zones; the CPN7 and CPN8 foraminiferal zones (equivalent to N9, N10 and N11 of global foraminiferal zones and to the MMi4a, MMi5 and MMi6 of Mediterranean foraminiferal zones) and by the mammalian zones MN9, MN10, MN13 and by Be isotopes. Sedimentation in basin began with basal conglomerates formed by local fan-deltas short before and during the initial rifting phase. Early Langhian conglomerates are composed of Mesozoic rocks derived from the sedimentary cover and nappe units of the Eastern Alps and Central Western Carpathians. The content of crystalline rocks increases upwards, which documents a continual denudation of the emerged source area (at present forming the pre-Neogene basement of the Danube Basin). The middle to late Langhian synrift stage of the basin development was accompanied by volcanic activity. Gravity transport of sediment took place on the basin slopes formed by pronounced fault activity. The basin floor reached the deep neritic zone. During the early Serravallian shelfal offshore sedimentary conditions prevailed and gradually passed into the late Serravallian regressive coastal plains with normal to brackish salinity. Tortonian transgressive sedimentation on the muddy shelves of Lake Pannon followed and was subsequently replaced by a relatively short-living deltaic environment and later by deposition on an alluvial plain. Final Pliocene to Quaternary fluvial sedimentation is characterized by gravel and sand beds. •

Several magmatic events based on U-Pb zircon geochronology were recognized in the Permian sedimentary succession of the Northern Gemeric Unit (NGU). The Kungurian magmatic event is dominant. The later magmatism stage was documented at the Permian-Triassic boundary. The detrital zircon assemblages from surrounding sediments documented the Sakmarian magmatic age. The post-orogenic extensional/transtensional faulting controlled the magma ascent and its emplacement. The magmatic products are represented by the calc-alkaline volcanic rocks, ranging from basaltic metaandesite to metarhyolite, associated with subordinate metabasalt. The whole group of the studied NGU Permian metavolcanics has values for the Nb/La ratio at (0.44-0.27) and for the Nb/U ratio at (9.55-4.18), which suggests that they represent mainly crustal melts. Magma derivation from continental crust or underplated crust is also indicated by high values of Y/Nb ratios, ranging from 1.63 to 4.01. The new 206 U-238 Pb zircon ages (concordia age at 269 ± 7 Ma) confirm the dominant Kungurian volcanic event in the NGU Permian sedimentary basin. Simultaneously, the Permian-Triassic boundary volcanism at 251 ± 4 Ma has been found for the first time. The NGU Permian volcanic activity was related to a polyphase extensional tectonic regime. Based on the new and previous U-Pb zircon ages, the bulk of the NGU Permian magmatic activity occurred during the Sakmarian and Kungurian. It was linked to the post-orogenic transpression/transtension tectonic movements that reflected the consolidation of the Variscan orogenic belt. The Permian-Triassic boundary magmatism was accompanied by extension, connected with the beginning of the Alpine Wilson cycle.

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Abstract:The Ratkovce 1 well, drilled in the Blatné depocenter of the northern Danube Basin penetrated the Miocene sedimentary record with a total thickness of 2000 m. Biostratigraphically, the NN4, NN5 and NN6 Zones of calcareous nannoplankton were documented; CPN7 and CPN8 foraminifer Zones (N9, 10, 11 of the global foraminiferal zonation; and MMi4a; MMi5 and MMi6 of the Mediterranean foraminiferal zonation were recognized. Sedimentology was based on description of well core material, and together with SP and RT logs, used to characterize paleoenvironmental conditions of the deposition. Five sedimentary facies were reconstructed: (1) fan-delta to onshore environment which developed during the Lower Badenian; (2) followed by the Lower Badenian proximal slope gravity currents sediments; (3) distal slope turbidites were deposited in the Lower and Upper Badenian; (4) at the very end of the Upper Badenian and during the Sarmatian a coastal plain of normal marine to brackish environment developed; (5) sedimentation finished with the Pannonian-Pliocene shallow lacustrine to alluvial plain deposits. The provenance analysis records that the sediment of the well-cores was derived from crystalline basement granitoides and gneisses and from the Permian to Lower Cretaceous sedimentary cover and nappe units of the Western Carpathians and the Eastern Alps. Moreover, the Lower Badenian volcanism was an important source of sediments in the lower part of the sequence.