Michal Kováč

ON LATE OLIGOCENE TO PLIOCENE DEPOCENTRE MIGRATIONS AND THE EVOLUTION OF THE CARPATHIAN-PANNONIAN SYSTEM

Abstract The Late Oligocene to Pliocene evolution of foredeep basins of the Eastern Alps-Carpathians fold and thrust belt is marked by pronounced internal to external and lateral depocentre shifts. The latter shifts, covering a present along-arc distance of 1700 km, portray accelerating rates of foredeep depocentre migration, particularly so in the late Early and in the Middle Miocene, from about 7 to about 45 cm/yr. Lateral depocentre migration came to a close at the beginning of the Late Miocene; the subsequent Late Miocene to Pliocene foredeep infill history was characterized by exponentially increasing accumulation rates in the intersection area of the East European (Ukrainian) and Moesian platforms. Successive steps in the evolution of the foredeep basins had pronounced counterparts in the intra-Carpathian area. The beginning of acceleration of foredeep depocentre migration in latest Early Miocene times was coeval with the inception of intra-Carpathian extensional tectonics. The extremely rapid Middle Miocene depocentre shift, coupled with a change in direction of foredeep depocentre migration, corresponded with maximum extension in the intra-Carpathian area. The ensuing end of foredeep depocentre migration around the Middle-Late Miocene transition was coeval with the end of extension of the intra-Carpathian area, which, in turn, was followed by the inception of overall, thermal subsidence at about 11.5 Ma. The timing of and spatial relationships between discrete, coeval events in arc and intra-arc evolution put unambiguous geological constraints on geodynamic modelling of the evolution of the Carpathian-Pannonian system. It is speculated that the geological observations may best be understood in terms of the surficial effects of lateral migration of slab detachment. Such effects would mirror the dominant role of a concentrating slab pull, taken to result in, e.g., a time-progressive acceleration of foredeep depocentre migration.

Quantitative subsidence analysis and forward modelling of the Vienna and Danube basins: thin-skinned versus thick-skinned extension

Abstract We present the results of a quantitative study of the tectonic evolution of the Vienna and Danube basins by comparing tectonic subsidence histories derived from backstripping of more than 90 wells from Slovakia, Hungary and Austria, with the predictions from forward tectonic modelling. Subsidence analysis and forward modelling, using a modified, non-uniform, extension model address the tectonic relations between different depocentres and the nature of tectonic subsidence. We derived stretching values for the Vienna basin between 1.04 and 1.30 for the crustal extension (δ) and between 1.00 (in the northern part) and 1.60 (southern part) for the lithospheric extension (β). The Danube basin is characterized by crustal extension values (δ) between 1.09 and 1.30 and lithospheric extension values (β) between 1.00 (northern part) and 1.60 (southern part). The Vienna basin shows a trend from thin-skinned extension in the northwestern part to whole lithospheric extension in the central-southern part. The subsidence history of the northwestern part of the Danube basin also reflects a thin-skinned extensional basin formation mechanism. The central and southern parts of the Danube basin show an important component of lithospheric extension. The basin evolution is strongly influenced by the rotating stress field through Miocene times, expressed in different phases of fault reactivation that are observed in the subsidence history.

Late Tertiary paleogeographic evolution of the Western Carpathians

Abstract The evolution of the Tertiary basins in the Western Carpathians was closely connected with the evolution of the Carpathian orogenic belt. During the Oligocene, the sea of the Outer Carpathian flysch troughs became for the first time part of the Paratethys regime due to isolation from the Mediterranean Tethys. Oblique collision between the North European Platform and the overriding West Carpathian Plate during the Early Miocene led to the development of the outer accretionary wedge, built up mainly from flysch nappes, and the formation of a foredeep. Intramontane basins developed in transpressional regime along the northern margin of the Early Alpine consolidated Central Carpathians, from where the sea also invaded the hinterland of the orogenic mountain chain. Progradation of the Alpine nappes gradually closed the Early Miocene (stage Eggenburgian) seaway in front of the Alps which led again to the isolation of the basins inside the West Carpathian segment. The marine connection with the Mediterranean started to open again through the West Carpathian hinterland at the end of the Early Miocene (stage Karpatian). In the Middle Miocene, the Outer Carpathian accretionary wedge obtained its present position, followed by the eastward migration of foredeep depocentres. Inside the orogenic belt large transtensional basins opened. The final closure of the marine connections (stage Badenian) led to a gradual decrease of salinity during the Late Miocene. The sedimentation in the Vienna, Danube (Little Hungarian plain) and East Slovakian (Transcarpathian) basins during the Late Miocene and Pliocene was influenced mainly by the thermal subsidence of the Pannonian domain.

The East Slovakian Basin — A complex back-arc basin

Abstract The East Slovakian Basin is situated on the junction of the Western and Eastern Carpathians. It is superimposed on the frontal part of the Carpathian internides, behind the Tertiary accretionary wedge of the Carpathian externides represented by the Flysch Belt. The development of the basin was controlled by the collision of the Carpathian orogen with the European platform and later by crustal extension and thermal subsidence in the Pannonian domain. The Early Miocene basin evolution was dominantly influenced by the collisional process. During the Eggenburgian, a narrow relic fore-arc basin was formed along the suture between the Carpathian internides and externides, nowadays represented by the Pieniny Klippen Belt. The compressive regime resulted in the disintegration of the basin, followed by the Ottnangian uplift and the development of a deep-seated dextral strike-slip fault zone. During the Karpatian, the central part of the basin was opened by a pull-apart mechanism, which stepwise changed to extensional basin evolution during the Lower and Middle Badenian. From the Upper Badenian on, the basin development was influenced by crustal extension associated with updoming of the mantle masses. A back-arc basin developed. During the Late Miocene, the East Slovakian Basin became a peripheral part of the Pannonian Basin System, where the sedimentation was controlled by the thermal subsidence at that time. During the Pontian and Pliocene a NE-SW-oriented compression was indicated.

Cretaceous—Quaternary tectonic evolution of the Tatra Mts (Western Carpathians): constraints from structural, sedimentary, geomorphological, and fission track data

Abstract The Tatra Mts area, located in the northernmost part of Central Western Carpathians on the border between Slovakia and Poland, underwent a complex Alpine tectonic evolution. This study integrates structural, sedimentary, and geomorphological data combined with fission track data from the Variscan granite rocks to discuss the Cretaceous to Quaternary tectonic and landscape evolution of the Tatra Mts. The presented data can be correlated with five principal tectonic stages (TS), including neotectonics. TS-1 (~95-80 Ma) is related to mid-Cretaceous nappe stacking when the Tatric Unit was overlain by Mesozoic sequences of the Fatric and Hronic Nappes. After nappe stacking the Tatric crystalline basement was exhumed (and cooled) in response to the Late Cretaceous/Paleogene orogenic collapse followed by orogen-parallel extension. This is supported by 70 to 60 Ma old zircon fission track ages. Extensional tectonics were replaced by transpression to transtension during the Late Paleocene to Eocene (TS-2; ~80-45 Ma). TS-3 (~45-20 Ma) is documented by thick Oligocene-lowermost Miocene sediments of the Central Carpathian Paleogene Basin which kept the underlying Tatric crystalline basement at elevated temperatures (ca. > 120 °C and < 200 °C). The TS-4 (~20-7 Ma) is linked to slow Miocene exhumation rate of the Tatric crystalline basement, as it is indicated by apatite fission track data of 9-12 Ma. The final shaping of the Tatra Mts has been linked to accelerated tectonic activity since the Pliocene (TS-5; ~7-0 Ma).

Neogene and Quaternary development of the Turiec Basin and landscape in its catchment: a tentative mass balance model

Neogene and Quaternary development of the Turiec Basin and landscape in its catchment: a tentative mass balance model The development of the Turiec Basin and landscape evolution in its catchment has been reconstructed by methods of geological research (structural geology, sedimentology, paleoecology, and geochronological data) as well as by geophysics and geomorphology. The basin and its surrounding mountains were a subject of a mass balance study during periods of tectonic activity, accompanied by considerable altitudinal differentiation of relief and also during quiet periods, characterized by a development of planation surfaces in the mountains. The coarse clastic alluvial fans deposited beneath the offshore pelitic sediments document the rapid Middle Miocene uplift of mountains on the margin of the Turiec Basin. The Late Miocene finegrained sedimentation represents the main fill of this basin and its origin was associated with the formation of planation surfaces in the surrounding mountains. The rapid uplift of the western and northern parts of the catchment area during the latest Miocene and Early Pliocene times further generated the deposition of coarse-grained alluvial fans. The Late Pliocene basin inversion, due to uplift of the whole Western Carpathians mountain chain, was associated with the formation of the Early Quaternary pediment and ultimately with the formation of the Turiec river terrace systems.

Late Miocene and Pliocene history of the Danube Basin: inferred from development of depositional systems and timing of sedimentary facies changes

Late Miocene and Pliocene history of the Danube Basin: inferred from development of depositional systems and timing of sedimentary facies changes The development of the northern Danube Basin (nDB) was closely related to the Late Miocene geodynamic evolution of the Pannonian Basin System. It started with a wide rifting which led to subsidence of several basin depocenters which were gradually filled during the Late Miocene and Early Pliocene. In the Late Pliocene the subsidence continued only in the basins central part, while the northern marginal zone suffered inversion and the uplifted sedimentary fill began to be eroded. Individual stages of the basin development are well recorded in its sedimentary succession, where at least three great tectono-sedimentary cycles were documented. Firstly, a lacustrine cycle containing Lower, Middle and lowermost Upper Pannonian sediments (A-F Zones; sensu Papp 1951) deposited in the time span 11.6-8.9 Ma and is represented in the nDB in Slovakia by the Ivanka and Beladice Formations. In the Danube Basin of the southern part in Hungary, where the formations are defined by the appearance of sedimentary facies in time and space, the equivalents are: (1) the deep-water setting marls, clays and sandy turbidites of the Endrod and Szolnok Formations leading to the overlying strata deposits of the basin paleoslope or delta-slope represented by the Algyő Formation, and (2) the final shallow-water setting deposits of marshes, lagoons and a coastal and delta plain composed of clays, sands and coal seams, represented by the Újfalu Formation. The second tectono-sedimentary cycle was deposited in an alluvial environment and it comprises the Upper Pannonian (G and H Zones; sensu Papp 1951) and Lower Pliocene sediments dated 8.9-4.1? Ma. The cycle is represented in the nDB, by the Volkovce Formation and in the southern part by the Zagyva Formation in Hungary. The sedimentary environment is characterized by a wide range of facies from fluvial, deltaic and ephemeral lake to marshes. The third tectono-sedimentary cycle comprises the Upper Pliocene sediments. In Slovakia these are represented by the Kolárovo Formation dated 4.1-2.6 Ma. The formation contains material of weathering crust preserved in fissures of Mesozoic carbonates, diluvial deposits and sediments of the alluvial environment.

Miocene vegetation pattern and climate change in the northwestern Central Paratethys domain (Czech and Slovak Republic)

Miocene vegetation pattern and climate change in the northwestern Central Paratethys domain (Czech and Slovak Republic) The case study area covers the slopes of the tectonically quiet European platform and foreland of the tectonically active Carpathian mountain chain (Carpathian Foredeep and Vienna Basin). Therefore the research on pollen spectra mirrors not only the evolution of landscape in two areas with different geodynamics, but also climatic changes in the Central Paratethys domain during the studied time interval. According to the pollen data, the Early to Middle Miocene vegetation reflects subtropical climate with very mild (negligible) cooling events during this period. This is indicated by common occurrence of thermophilous taxa in the whole sedimentary record. The Middle Miocene landscape evolution, conditioned by uplift of the Carpathian mountain chain and subsidence of adjacent lowlands, led to commencement of the altitudinal zonation. The terrestrial and aquatic ecosystems confirm a subtropical climate (Miocene Climatic Optimum, Mi3 event) with some possible long term changes in humidity. The Late Miocene paleogeographical changes, but also general climatic oscillations in the northwestern Central Paratethys realm, resulted in decrease of the number of thermophilous taxa during this time (change in latitudinal position of the vegetation cover). Variously high mountain relief of the uplifted mountain chains (altitudinal zonality) created ideal conditions for mixed mesophytic forests (to open woodland — open grassland type), still with presence of evergreen taxa. A subtropical climate with gradual transition to warm temperate climatic conditions is supposed on the basis of the reconstructed vegetation cover.

Late Miocene sedimentary record of the Danube/Kisalföld Basin: Interregional correlation of depositional systems, stratigraphy and structural evolution

Abstract The Danube / Kisalföld Basin is the north-western sub-basin of the Pannonian Basin System. The lithostratigraphic subdivision of the several-km-thick Upper Miocene to Pliocene sedimentary succession related to Lake Pannon has been developed independently in Slovakia and Hungary. A study of the sedimentary formations across the entire basin led us to claim that these formations are identical or similar between the two basin parts to such an extent that their correlation is indeed a matter of nomenclature only. Nemčiňany corresponds to the Kálla Formation, representing locally derived coarse clastics along the basin margins (11- 9.5 Ma). The deep lacustrine sediments are collectively designated the Ivanka Formation in Slovakia, while in Hungary they are subdivided into Szák (fine-grained transgressive deposits above basement highs, 10.5 - 8.9 Ma), Endrőd (deep lacustrine marls, 11.6 -10 Ma), Szolnok (turbidites, 10.5 - 9.2 Ma) and Algyő Formations (fine-grained slope deposits, 10 - 9 Ma). The Beladice Formation represents shallow lacustrine deltaic deposits, fully corresponding to Újfalu (10.5 - 8.7 Ma). The overlying fluvial deposits are the Volkovce and Zagyva Formations (10 - 6 Ma). The synoptic description and characterization of these sediments offer a basin-wide insight into the development of the basin during the Late Miocene. The turbidite systems, the slope, the overlying deltaic and fluvial systems are all genetically related and are coeval at any time slice after the regression of Lake Pannon initiated about 10 Ma ago. All these formations get younger towards the S, SE as the progradation of the shelf-slope went on. The basin got filled up to lake level by 8.7 Ma, since then fluvial deposition dominated.

Neogene history of intramontane basins in the western part of the Carpathians

Neogene collision of the Carpathians with the European Platform resulted in flysch nappes overthrust in frontal part of the orogene. Tectonic activation of the Paleoalpine-consolidated Centrai Western Carpathians led to modification of their structural pattern. Axis of the main compression rotated from NW-SE to NE-SW. Thrust-reverse faults and ENE-WSW dextral strike- slips were dominant in the Lower Miocene. Movement of the Western Carpathians north-eastward during the Middle and Upper Miocene caused activation of ENE-WSW sinistrai strike-slips and NE-SW normai faults. Pliocene regional extension was manifested mainly by NE-SW normai faults which controlled the sedimentation and form of the basins.