Ytp ita - i peni giganti del triassico
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Shallow marine siliciclastic or carbonate siliciclastic overstep sequences started in the internal part of the Variscan orogenic belt during the latest Serpukhovian and Bashkirian—Moscovian. They overlapped unconformably the variably metamorphosed Variscan basement, or weakly deformed and metamorphosed foreland and syn-orogenic flysch sediments of Mississippian to Early Pennsylvanian age.
The post-Variscan rifting largely affected the Variscan orogenic belt by reactivation of the Variscan lithosphere. It continued gradually to terrestrial-shallow water carbonate-siliciclastic sequences in its external part through the Per- mian.
Key words: Pennsylvanian—Permian, Variscan post-orogenic stage, Circum Pannonian Region, tectono-paleoenvironments, paleogeography. Introduction the Pennsylvanian-Cisuralian late- and post-Variscan orogenic stage.
The Guadalupian—Lopingian Epoch is not documented The Pennsylvanian—Permian succession of the Circum Pan- in this map, although it is very important for interpretation of nonian Region CPR records the change from the Pangaean the beginning of the Alpine orogenic cycle.
As the transgres- configuration and compressive regime inherited from the sion of the Tethys Sea prograded during the Guadalupian— Variscan orogeny, to the development of a broad zone of Lopingian up to Early Triassic gradually from the South to the strike-slip and extensional basins. The subsequent thermal North according to the present position of unitsthe distribu- subsidence led to the gradual coalescence of these isolated tion of these sediments in the CPR realm is an important phe- basins.
Large evaporitic sabkha pene in Permiano salt pan to shallow water nomenon pene in Permiano the interpretation pene in Permiano Variscan and Alpine geody- environments were formed at the beginning of the Alpine namic evolution. To minimize this lack we include brief orogenic cycle. This was caused by the post-Cisuralian—Ear- information on the Guadalupian—Lopingian environments in ly Triassic extension and transgression of the shallow Neo- the Pennsylvanian—Cisuralian explanation text. The numbers indicate schematical- ly the position of the described tectonostratigraphic units documented in Pene in Permiano.
The explana- in the Circum Pannonian Region tory pene in Permiano and stratigraphic columns Figs. Therefore, the nomination of the tectonic units changes, vertical tectonics and finally the transgression of the generally follows the terms of terrane tectonics as used for Neotethys Sea: IGCP No.
Pene in Permiano Guadalupian-Lopingian continental deposits merging structural framework. Based on the lithological correla- tions, the whole sequence is generally divided into: i the lower, coarse-grained Guadalupian?
It is divided into the Induan and Olenekian stages. A lithostratigraphic synonym for these sequences is the Germanic Lower Triassic Buntsandstein. Due to the strong Alpine deformation and overprinting the mutual relationship between these two sedimentary complexes is un- clear. On the basis of distinct differences in mineralogical ma- turity a disconformity between them could be suggested.
Further information is given in Tollmann,OberhauserKrainer Gurktal Nappe System Stolzalpe Nappe The Variscan basement in this region is composed of de- formed and weakly metamorphosed sedimentary and volcanic rocks of Ordovician to Mississippian age. The lowermost part is composed pene in Permiano polymict conglomer- Pene in Permiano. Legend to lithostratigraphic columns Figs.
Legend in Fig. Several meters of thick tions show in the present geographic orientation a distinct east- dark shales containing abundant well pene in Permiano plant fossils are ward trend indicating that the sediments of the Stangnock For- developed at the top of these megasequences. About 80 species mation were deposited in an approximately E-W-trending of plant fossils have been described from the interbedded shales intermontane basin.
The sharp erosional contact at the base of and thus suggest the Kasimovian—Gzhelian age Tenchov ; the megasequence is interpreted as a result of pene in Permiano Krainer a,b,; Fritz et al. Current direc- block faulting Krainer For this reason all Carboniferous sequences from channel, bar and overbank sediments. Thin anthracite pene in Permiano the Veitsch Nappe up to the Moscovian are described together occur in places.
Overbank shales contain well preserved plant with the Devonian-Carboniferous pre-flysch and flysch envi- pene in Permiano. Some assemblages contain about 30 taxa suggesting ronments in the Pene in Permiano Pannonian Region Ebner et al.
The pene in Permiano and mineralogical composi- Pene in Permiano the Pene in Permiano Nappe of the Graywacke Zone, Upper Per- tion pene in Permiano the sediments are very similar to the Stangnock Forma- mian Alpine Verrucano occurs pene in Permiano within the thin Alpine tion of the Gurktal Nappe, the sediments were probably Silbersberg thrust-sheet Neubauer et al. The Variscan pile is over- as a consequence of the Saalian movements.
Proxi- lain with an angular unconformity by conglomeratic mal to distal alluvial red-beds, grading into fine-grained formations Präbichl Formation which grade upwards in the sandflat-playa complexes with caliche crust and thin algal continental red-beds and sabkha sediments Hochfilzen layers in some places, characterize the Cisuralian lower pene in Permiano Group.
In most cases, these sediments overlie with angular the early Alpine rifting stage. Compared to the Drazug and unconformity the Variscan crystalline basement the Gailtal Stolzalpe Nappe of the Gurktal Thrust System, the mutual metamorphic rocks in the Drauzugor different weakly transition from continental coarse-grained Guadalupian-Lop- metamorphosed Variscan metasediments.
At the NW margin ingian sediments to lagoonal-sabkha facies is proved at the of the Stolzalpe Nappe, the Cisuralian red-beds overstepped basement of the Northern Calcareous Alps.
Flora from the basal parts of these red-beds proved The Western Carpathians the Cisuralian age van Ameron et al. Generally, the sediments are rich in clasts derived Structural fragments of newly formed epi-Variscan crust from the local basement polymict conglomerates, lithic were incorporated in the paleo-Alpine Western Carpathian arenites and greywackes.
Like most of the other collisional fold belts, the In the Pene in Permiano, Stolzalpe Nappe of the Gurktal Thrust Sys- Western Carpathians have been traditionally divided into tem and the westernmost part of the Northern Calcareous external and internal structural zones. Pene in Permiano on the palyno- morphic effects is the main pene in Permiano between the distin- logical data from lacustrine sediments within the equivalent guished structural zones.
This pene in Permiano Cretaceous nappe system comprises The Guadalupian-Lopingian siliciclastic red-bed sediments the crystalline massifs with their Late Paleozoic overstep of the ephemeral braided river and playa system of the Gröden sequences.
According to Krainer this hi- tion and collision events. This triple division of the mum thickness of the Gröden Formation is ca. These West Carpathian orogenic belt is more acceptable from the sediments contain large amounts of redeposited acid volcani- standpoint of the Variscan geodynamic evolution and con- clastic fragments derived from the underlying Cisuralian se- sequently of the Alpine tectono-thermal cycle.
Regardless of their Gurktal Thrust System. Relics of these Variscan crustal fragments are preserved within the main Al- The whole Carboniferous sequence of the Veitsch Nappe is pine crustal nappe units together with their characteristic composed of syn- to late-orogenic sediments which were de- post-Variscan overstepped sequences Fig.
Their stratigraphic range was estab- proximity of a plant covered continent. Most others were de- Their lithology consists of repeated Nappes according to Andrusov et al. Due to their inter- small fining-upward sedimentary cycles with the prevalent nal structure and mutual relationships as well as facies charac- conglomeratic or sandy-conglomeratic components.
Minor teristics these partial nappes have been distinguished as mainly black shale and siltstone intercalations occur in the upper part Triassic complexes. Both Hronic Nappe subunits contain Upper of the sequence. The dating, Late Moscovian—Kasimovian, is Paleozoic volcano-sedimentary formations, preserved variably based on dominant microflora. The Kasimovian age was proved mainly by macrof- ern Gemeric or higher Mesozoic nappe units.
Pene in Permiano assemblages also confirm the Kasimovian There is no evidence of the underlying pre-Upper Pennsyl- range. The Kasimovian age was inferred from plant find- Tectonic slices of granitoid blastomylonites found in the basal ings. The of tree trunks and barks. The most typical feature is limestones, indicate the limnic-fluvial and swamp environ- the numerous small repeating fining-upward sedimentary cy- ments. The second large cycle is characterized by alluvial cles. Abundant graded-bedded sandstones with minor mud- stream-channel lithofacies, with dominant sandstones and ab- stone intercalations, as well as layers rich in plant detritus sence of the coal-bearing association.
Several levels of pene in Permiano indicate a fluvial-lacustrine delta association. Pene in Permiano sequences kaline rhyolite-dacite and their volcaniclastics are typical of of the fine-grained sandstones, mudstones and shales of grey this part of the sequence. Thick layers of rhyolite-dacite volca- to black colour correspond to pene in Permiano lithofacies.
Synge- niclastics incl. The rift-related sediments of the Hronicum showed a trend The Southern Veporicum Carboniferous post-orogenic se- towards of older and older supplies of detrital mica in an up- quence is represented by the upward-coarsening Kasimovian- ward direction. These line rhyolites with their tuffs are present. The Ci- croflora assemblages. Sharp change in sediment colour is related to ternating conglomerates, sandstones and shales.
Lenses of do- rapid increase of aridity. The Tatricum Permian sediments are not were deposited in braided alluvial and fluvial-lacustrine envi- very thick, and are preserved only in isolated areas e. The basal part of each megacycle comprises able overstepping of medium- to high-grade Variscan crystal- channel-lag and point-bar deposits, associated laterally with line basement; continental, proximal to distal braided-alluvial floodplain and levee sequences. The upper part of each mega- sediments conglomerates, coarse-grained sandstones.
The cycle is characterized by playa, rare continental sabkha and sediments lack fossils. Scarce presence of rhyolites and their ephemeral lake deposits. An important phenomenon is the volcaniclastics show a calc-alkaline trend.
Dostal et al. The important magneto- rivers. Coeval rift-related volcanic activity resulted in calc-al- stratigraphic data, confirming the position of the Illawara pene in Permiano dacite effusions, associated pene in Permiano pyroclastic flows ign- Reversal Horizon were obtained from the upper part of the imbrites and epiclastic deposits.
On the basis of their volcaniclastics show affinity to a tholeiitic magmatic these magnetostratigraphical and biostratigraphical results, the trend. The age.
Saalian movements, is documented by a change of drainage Sediments indicate alluvial fan to piedmont flood and along the Southern Veporic-Northern Gemeric tec- plain environments with isolated distal ephemeral lakes.
The regional megacycles with polymict conglomerates at the base, age of the A-type group magmatites is known from the con- both reflect the synsedimentary tectonic. Analyses of the volcanic genic sedimentation started during the Early Permian.
All horizons indicate that activity was polyphase. Due to very narrow spatial and compositional relation- a consequence of the break in sedimentation at the end of the ships between the marine Upper Bashkirian-Moscovian and Cisuralian Saalian movements and the beginning of the Al- the syn-orogenic Mississippian sequence, these formations pine sedimentary cycle.
However, the biostratigraphic evidence were described in more detail together with the Carboniferous supporting this assumption is missing.