The south-eastern part of the basement of the Pannonian Basin is made up of Variscan crystalline complexes and early Mesozoic formations showing striking affinity with the corresponding formations in the southern margin of the European Plate. This large composite structural unit, which is actually an exotic terrane of European Plate origin, has been named the Tisza Mega-unit. Based upon relevant data of the pre-Tertiary basement of southern Hungary the reconstruction of the position of the Tisza Terrane in the early Alpine evolutionary stages, the process of its separation and break-off from the European Plate, and results of its Eo-Alpine deformations are summarised in the present paper. In the Variscan and early Alpine evolutionary stages the area of the later Tisza Mega-unit was located at the margin of the European Plate. During Variscan orogeny terrane accretion led to intensive deformation and metamorphism in this belt. This was followed by transpressional tectonics and the development of molasse basins in the late and post-Variscan stages, and passive margin evolution after the Neotethys opening in the Middle Triassic. The separation of the Tisza Mega-unit began with incipient continental rifting along the axis of the later Ligurian-Penninic-Vahic oceanic branch in the Late Triassic. The end of terrigenous material deposition in the most external zones, and a coeval change in fossil assemblage, point to the separation of the Tisza Block from the European Plate in the Early Bathonian. Significant rotation of the Tisza Mega-unit and coeval paroxysm of alkaline rift-type basalt volcanism took place in the Early Cretaceous. In the mid-Cretaceous, due to the northward motion of the Adria Block and the related closure of the westernmost Neotethys basin, the extensional regime changed to a compressional one, leading to onset of the nappe stacking and low-grade regional metamorphism within the Tisza microplate. In the foreland of the nappe systems flexural basins came into existence that are characterised by flysch-type sedimentation. In the Early Tertiary the northeastward motion of the Alcapa and Tisza + Dacia Blocks led to the formation of the present-day heterogeneous basement of the Pannonian Basin.
With 9 figures and 4 plates Abstract. During mapping between Aggtelek, J6svafO and Egerszog (Aggtelek Hills, Silica Nappe) a new basinal limestone sequence was recognised in between the Steinalm and Wetterstein platform limestones. It comprises Schreyeralm Fm. (base) and Raming Fm. (top). The latter one is new for Hungary. We describe two sections (Nagy Jenei Hill and Baradla Cave). In both the Schreyeralm Fm. is characterised by reddish coquina rich micritic limestone. The Raming Fm. consists of allodapic calcarenites and reef detritus sandwiched between filament mudto wackestones. In the upper part, the resedimented reef detritus becomes more and more frequent. In the Baradla Cave section radiolarite beds with a tuffite intercalation terminate the basinal succession. The base of the Schreyeralm Fm. is heterochronous (late Pelsonian to PelsonianlIlIyrian). The base of the Raming Fm. contains conodonts referring to an age interval of Trinodosus up to most part of Reitzi Zone (early-middle Illyrian). The top is also heterochronous.lts age is middle Illyrian (Trinodosus-most part of Reitzi Zone) in the NW and Fassanian (Curionii Zone) in the SE part. The sedimentation was controlled by a halfgraben morphology of the basement. The closest similarity to this formation can be found in the Slovak part of the Silica Nappe and in well oxigenated zones of Reifling basin in the Hronic Unit. In the Juvavic Domain of the Northern Calcareous Alps the "Southern" slope facies (sensu Mandl 1999 , 2000) of the Wetterstein platform , where Raming-type allodapic limestones interfinger with open marine variegated pelagic carbonates, is closely related to the newly recognised Raming Fm. in the Aggtelek Hills.
Based on selected sections of the Northern Calcareous Alps (NCA) and Aggtelek Mountains, this study compares the time and the reason for the drowning of the Steinalm ramp. The investigated sections were chosen from the NCA (Upper Austoalpine Nappes), 1) Juvavikum: Schreiergraben, Schreierkogel/Schreyeralm The Steinalm Limestone Formation is light grey, bedded and in dasycladaleans (Physoporella pauciforata, Poncetella hexaster, Oligoporella pilosa, Teutloporella peniculiformis) rich grainstone, Meandrospira dinarica is also present. This formation is Pelsonian in age and signs of terrestrial influence (meteoric diagenesis, carstification) were not detected.In the Schreiergraben outcrop the lowermost layers of the Schreyeralm Limestone Formation consist of breccia. The lithoclasts originate from the Steinalm Limestone Fm. Above the breccia the limestone, bedded, homogenous "filament" wackestone can be found. This might represent a sediment of the lower slope or toe-of-slope. Conodonts from the matrix (Gondolella bulgarica, Nicoraella germanica) indicate a Pelsonian age. 20 m above the base Gondolella cornuta, G. liebermanni and Gladigondolella tethydis suggest a Lower-Middle Illyrian age (age interval between TrinodosusLiepoldti Subzones)Schreierkogel: the lower part of the Schreyeralm Limestone Fm was preserved only in red neptunian dykes of the Steinalm Limestone. The microfacies is "filament" wackestone. The ages are Late-Pelsonian (Gondolella bulgarica, G. bifurcata) and Early Illyrian (Gondolella cornuta, G. praeszaboi, G. excelsa, Gladigondolella budurovi).2) Bajuvaricum: Bajuvaricum: Nixhöhle/Frankenfels. The Annaberg Limestone is thick-bedded, light grey, slightly dolomitized limestone with pelsparitic microfacies. Upsection it is followed by 10 m-thick, thick-bedded Reifling Limestone. The microfacies is "filament" wackestone. The Gondolella bulgarica at its base is indicative of a Pelsonian age.Hocheck/Annaberg. The grey, thick bedded Annaberg Limestone consists of an alternation of mudstones and packstones containing Teutloporella peniculiformis. Meandrospira dinarica indicates a Pelsonian age. At the base of the overlaying Reifling Limestone Gondolella bulgarica also suggests a Pelsonian age.Palfau. The uppermost part of the Steinalm Limestone consists of light grey, oncoidal beds. Above it can be found thin-bedded cherty limestone (Reifling Limestone); this is very rich in conodonts although only one species (Gondolella bifurcata) is present. The age is Pelsonian.In the Aggtelek Mountains (Silica Nappe, Alcapa Megaunit), the drowning of the Steinalm platform was studied in two sections 1) Baradla Cave, 2) Nagy-Jenei Hill.The thickness of the Steinalm Limestone and the succession of the microfacies is identical across the whole area. The microfacies succession can be followed along a strike. The lower part is represented by cyclic peritidal sediments; in the upper part there are calcarenites which are rich in dasycladaleans (Physoporella pauciforata, Teutloporella penicu liformis, Poncetella h...
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