Neogene stress field in the central and eastern parts of the outer Polish Carpathian Foredeep

The Polish Carpathian Foredeep (PCF) is a foreland basin formed during the regional flexure of the East European continental lithosphere related to a continental collision in the Carpathian realm. The infill of the PCF basin consist of the uppermost Lower to the Upper Miocene (Ottnangian-Pannonian) sediments. These are mostly mudstones and clays, more rarely sandstones, limestones and evaporites. Numerous thrusts, strike-slip and normal faults, and even folds exist in the whole PCF. The orientation of these structures is variable but they show the privileged directions. The spatial analysis of structures and their crosscutting relationships, together with published seismic data permit conclude that the regional stress field in studied part of PCF was stable during the whole Neogene time till now. The orientation of the maximum horizontal stress axis was NNE-SSW. The local changes of the stress field orientation were caused by activity of the strike-slip fault in the foredeep basement or even the rotation of the basement blocks. The visible response on the basement activity were mostly outcrop-scale structures, namely the number and variety of structures are increasing in individual outcrop. However, the map-scale structures were also generated, for example so called Ryszkowa Wola Horst, a large pop-up structure.     

Palaeogeographic and burial controls on anhydrite genesis: the Badenian basin in the Carpathian Foredeep (southern Poland, western Ukraine)

The Badenian (Middle Miocene) Ca-sulphate deposits of the fore-Carpathian basin – including the shelf and adjacent salt depocentre – have undergone varying degrees of diagenetic change: they are preserved mainly as primary gypsum in the peripheral part of the platform, whereas toward the centre of the basin, where great subsidence occurred during the Miocene, they have been totally transformed into anhydrite. The facies variation and sequence of Badenian anhydrites reflect different genetic patterns of two members of the Ca-sulphate formation. In the lower member (restricted to the platform), anhydrite formed mainly by synsedimentary anhydritization (via nodule formation), whereas in the upper member (distributed throughout the platform and depocentre) the various gypsum/anhydrite lithofacies display a continuum of distinctive anhydrite type-fabrics. These fabrics are based on petrographic features and show from the centre to the margin: (1) syndepositional, interstitial growth of displacive anhydrite; (2) early diagenetic, displacive to replacive (by replacement of former gypsum) anhydrite formation near the depositional surface; (3) early diagenetic, displacive to replacive anhydrite formation during shallow burial; and (4) late-diagenetic (and only partial) replacement of gypsum at deeper burial. The cross-shelf lateral relations of anhydrite lithofacies and fabrics suggest that the diagenesis developed as a diachronous process. These fabrics of the upper member reflect both palaeogeographic (linked to different parts of the basin) and burial controls. Anhydrite growth started very early in the basin centre, presumably related to high-salinity pore fluids; anhydritization prograded updip toward the shelf (landward in a generalized cross-section through the basin). The intensity of gypsum replacement by anhydrite was progressively attenuated landward by a decrease in the salinity of the pore fluids. In each part of the basin, the anhydrite fabric was also controlled by the texture and degree of lithification of the fine-grained primary gypsum lithofacies. Recrystallization of these anhydrite fabrics during late diagenesis, linked to deeper burial conditions, is insignificant, allowing reconstruction of the original anhydritization pattern.     

Strontium isotope composition of Middle Miocene primary gypsum (Badenian of the Polish Carpathian Foredeep Basin): evidence for continual non‐marine inflow of radiogenic strontium into evaporite basin

Strontium isotope compositions of ancient sulphate deposits not only provide chemostratigraphic information but also offer insight into the system in which the evaporites precipitated. Primary gypsum from two Middle Miocene (Badenian) sections in southern Poland shows steadily higher ⁸⁷Sr/⁸⁶Sr ratios than those expected from a marine‐derived formation. The ratios are interpreted as the result of increasing inflow into the basin at the time of gypsum precipitation. Palaeogeographic reconstructions suggest that riverine runoff sources were situated in the West and East European platforms (to the north and east, respectively) and the Carpathians (to the south), which are mostly composed of Mesozoic sedimentary rocks; their dissolution cannot be responsible for the higher ⁸⁷Sr/⁸⁶Sr ratios recorded. We conclude that Archaean and Palaeoproterozoic igneous and supracrustal rocks of the Ukrainian Shield were the source of the higher ⁸⁷Sr/⁸⁶Sr ratios recorded in the Badenian primary gypsum. A distinctive decreasing trend of ⁸⁷Sr/⁸⁶Sr ratios from western Ukraine to southern Poland is explained by a consistent direction of brine inflow during gypsum crystallization (typical cyclonic circulation controlled by the Coriolis effect).     

Paleogeography of the Early Badenian connection between the Vienna Basin and the Carpathian Foredeep

The paleogeographic reconstruction for an early Badenian connection of the Vienna Basin and the Carpathian Foredeep in the Mikulov area (Mikulov Gate) based on paleontological (otoliths) and geological (regional geology, tectonics) data has been provided. The ecologically homogenous deep water associations of otoliths in the most NW tip of the Vienna Basin (Sedlec HJ-2 Borehole) links up bathymetrically with nearly adequate otolith assemblages in the southernmost Moravian part of the foredeep. Ten meso- and bathypelagic teleost species have been identified in the Vienna Basin for the first time. Geological analyses proved inversion processes of recurrent nature along old faults of the NW-SE direction in the Dyje (Thaya) Depression. In the early Badenian the Mikulov Gate resulted from the sagging block of the Waschberg Zone. This marine channel was relatively deep (> 200m, as indicated by otoliths) and in all probability flooded an entire front of the nappes in this area.     

Foraminiferal record of marine transgression during deposition of the Middle Miocene Badenian evaporites in Central Paratethys (Borków section,Polish Carpathian Foredeep)

Benthic and planktonic foraminifera from a marly clay intercalation sandwiched between mid‐Badenian (Middle Miocene) gypsum deposited in an environment of an evaporitic shoal (<1 m deep) at Borków (southern Poland) indicate a major marine flooding event in the previously isolated Carpathian Foredeep Basin (Central Paratethys). After this very short‐term environmental change, benthic foraminifers started to colonize a new niche which was previously defaunated, and the pattern of benthic foraminiferal colonization is similar to that related to the reflooding which terminated the Badenian evaporite deposition. The benthic foraminifer assemblages are composed of pioneer, opportunistic, r‐selected species dominated by elphidiids. The connection of the Carpathian Foredeep Basin with the marine reservoir was short‐lived. The marly clay intercalations in evaporite sequences originating in bared basins can thus register major environmental changes.     

Isotopic abundances of water of crystallization of gypsum from the Miocene evaporite formation,Carpathian Foredeep,Poland

For sulfates of Miocene evaporites in the Carpathian Foredeep, the waters of crystallization of gypsum (w.c.g.) have $\text{δD = ?38 to ?113\%.}$ and $\text{δ}{}^{18}\text{O = 0 to ?11\%.}$ (SMOW). The $\text{δ}{}^{34}\text{S}$ and $\text{δ}{}^{18}\text{O}$ values of the sulfates are uniform and consistent with a marine origin. It is proposed that the original w.c.g. was equilibrated with marine water. Subsequently, it re-equilibrated towards very isotopically light water (δD ～ ?100%., δ¹⁸O ～ ?14%) during a glacial or postglacial period and is now trending towards current waters circulating through the deposits (δD ～ ?50%., δ¹⁸ ～ ?7%). The extent of reequilibration increased with decreasing crystal size.     

Soil gas composition above gas deposits and perspective structures of the Carpathian Foredeep,SE Poland

In 2001 a surface geochemical survey was carried out in the Carpathian Foredeep, in the area between Jaros?aw and Radymno (SE Poland) where multihorizon gas deposits were discovered. These deposits accumulate microbial CH₄ with small amounts of N₂ and higher molecular weight gaseous hydrocarbons. Soil–gas composition in the hydrocarbon fields in the study area is relatively different from the original composition of natural gas occurring in the subsurface reservoir. In 449 analyzed soil gas samples collected from 1.2 m depth relatively low concentrations were found for CH₄ (median value 2.2 ppm) and its homologues (median value of total alkanes C₂–C₄ – 0.02 ppm). Alkenes were encountered in 36.3% of the analyzed samples (mean value of total alkenes C₂–C₄ – 0.015 ppm) together with distinctly higher concentrations of H₂ (maximum value – 544 ppm, mean value – 42 ppm) and CO₂ (maximum value – 10.26 vol.%, mean value – 2.27 vol.%). Individual, very high concentrations of CH₄ (up to about 35 vol.%) resulted from sub-surface biochemical reactions whereas higher alkanes detected in soil gases (up to about 68 ppm) originated from deep gas accumulations. Both the H₂ and alkenes may be indirect indicators of deep hydrocarbon accumulations. Carbon dioxide may also be useful for hydrocarbon exploration, revealing increased concentrations in those sampling sites where CH₄ concentrations are strongly depleted, presumably due to bacterial oxidation. These relationships are valid only for the study area and should not be extended as an universal principle.     

Late Cretaceous to early Miocene deposits of the Carpathian foreland basin in southern Moravia

 The Late Cretaceous to Early Miocene strata of the Carpathian foreland basin in southern Moravia (Czech Republic) are represented by a variety of facies which reflects the evolution of the foreland depositional system. However, because of the intensive deformation and tectonic displacement and the lack of diagnostic fossils the stratigraphic correlation and paleogeographic interpretation of these strata are difficult and often controversial. In order to better correlate and to integrate them into a broader Alpine–Carpathian foreland depositional system, these discontinuous and fragmentary strata have been related to four major tectonic and depositional events: (a) formation of the Carpathian foreland basin in Late Cretaceous which followed the subduction of Tethys and subsequent deformation of the Inner Alps-Carpathians; (b) Middle to Late Eocene transgression over the European foreland and the Carpathian fold belt accompanied by deepening of the foreland basin and deposition of organic-rich Menilitic Formation; (c) Late Oligocene to Early Miocene (Egerian) uplifting and deformation of inner zones of the Carpathian flysch belt and deposition of Krosno-type flysch in the foreland basin; and (d) Early Miocene (Eggenburgian) marine transgression and formation of late orogenic and postorogenic molasse-type foreland basin in the foreland. These four principal events and corresponding depositional sequences are recognized throughout the region and can be used as a framework for regional correlation within the Alpine–Carpathian foreland basin. Received: 18 August 1998 / Accepted: 9 June 1999     

Foraminiferal biostratigraphy of the Albian and Cenomanian sediments in the Polish part of the Pieniny Klippen Belt,Carpathian Mountains

Seven local biostratigraphic zones have been distinguished in the Albian and Cenomanian sediments of the Pieniny Klippen Belt: Hedbergella assemblage (Assemblage Zone, AZ), R. subticinensis-R. ticinensis (Concurrent Range Zone, CRZ), R. ticinensis- P. praebuxtorfi (CRZ), R. ticinensis- P. buxtorfi (Partial Concurrent Range Zone, PCRZ), P. buxtorfi- R. appenninica (CRZ), R. appenninica (Partial Range Zone, PRZ) and R. reicheli- R. green-hornensis (PCRZ), The zones are tentatively correlated with the ortho- and parastratigraphic zones of the Albian and Cenomanian. Three palaeoecological associations have been distinguished: “Czorsztyn”, shelf-upper slope, large proportion of nodosarids and miliolids; “Pieniny A” middle part of slope, oligotaxic planktonic assemblages dominant; “Pieniny B”, depth similar to that of “Pieniny A”, larger proportion of agglutinated foraminifers. All fall within the “Marssonella” association sensu Haig, 1979, Haig, 1979. Layers of black shales, interpreted to reflect Cretaceous oceanic anoxic events, are correlated between successions of the Pieniny Klippen Belt, and their biostratigraphical position is determined.     

The thickest and the most complete loess sequence in the Carpathian basin: the borehole Udvari-2A

The key geological borehole Udvari-2A is located in Hungary at the Tolna Hegyhat Hills, in the central part of the Carpathian basin. Its detailed interpretation yielded valuable information on the stratigraphy and the post-Pannonian continental sedimentation regime of this territory. Stratigraphic data provided by the borehole facilitated the drawing up of a more precise picture on the post-Pannonian paleoenvironment and history of the evolution of the area. The borehole cut a thick series of the post-Pannonian Tengelic formation and the overlying, presumably complete sequence of the continental loess sediments of this region. The magnetostratigraphic correlation indicates that the 97 m thick loess sequence in the borehole Udvari-2A is the thickest and most complete so far recorded in Hungary and the deposition of loess started approximately at 1.1 Ma. In this sequence each of the four separable sedimentary periods of the loess are represented by distinct sediments. A theoretical stratigraphic column is also outlined to describe the Paks Loess Formation using data from the SE Transdanubia, defining and characterizing its lithological units. Since the formation is widely known, it was possible to correlate the most complete loess sequence in the Carpathian basin with the Marine Isotope Stages, and this opens up new opportunities for global correlation.     

Sedimentation in the Carpathian Flysch sea

On the ground of the sedimentary features of the Flysch the general conditions of sedimentation in the Carpathian Flysch sea are tentatively reconstructed. It is admitted that the Carpathian Flysch has been deposited in a fairly deep basin under the influence of turbidity currents. The directions of transport are presented and the distances covered by currents estimated. Some inferences concerning the shape and relief of the basin are discussed.     

Stages in the Magura Basin: a case study of the Polish sector (Western Carpathians)

The Magura Basin domain developed in its initial stage as a Jurassic-Early Cretaceous rifted passive margin that faced the eastern parts of the oceanic Alpine Tethys. In the pre- and syn-orogenic evolution of the Magura Basin the following prominent periods can be distinguished: Middle Jurassic-Early Cretaceous syn-rift opening of basins (1) followed by Early Cretaceous post-rift thermal subsidence (2), latest Cretaceous–Paleocene syn-collisional inversion (3), Late Paleocene to Middle Eocene flexural subsidence (4) and Late Eocene - Early Miocene synorogenic closing of the basin (5). The driving forces of tectonic subsidence of the basin were syn-rift and thermal post-rift processes, as well as tectonic loads related to the emplacement of accretionary wedge. This process was initiated at the end of the Paleocene at the Pieniny Klippen Belt (PKB)/Magura Basin boundary and was completed during Late Oligocene in the northern part of the Magura Basin. During Early Miocene the Magura Basin was finally folded, thrusted and uplifted as the Magura Nappe.     

Bryozoan event from Middle Miocene (Early Badenian) lower neritic sediments from the locality Kralice nad Oslavou (Central Paratethys,Moravian part of the Carpathian Foredeep)

Fossil Bryozoa occurs usually in shallow-water environments. One of the rare deep-water associations of Bryozoa has been studied in a profile at Kralice nad Oslavou. According to studies of foraminifera, the paleodepth was more than 150 m and less than 500 m. The bryozoan assemblages are poor, consisting of four species only, dominated by Tervia irregularis (Cyclostomatida) and Reteporella kralicensis sp.n. (Cheilostomatida), a new species being described in detail.     

Structural paragenesises of the flysch complexes in the central part of the Uralian Foredeep

The structural features of the Upper Paleozoic flysch formations in the central part of the Cis-Uralian Foredeep were studied. Three types of structural paragenesises typical of thrust zones were distinguished. Among them are west vergent inclined folds and overfolds that pass into recumbent folds near a fault plane, structured tectonic melange, local thrusts, schistosity zones, and flat slipping planes. The various structural elements extend from northwest to northeast, due to the structural heterogeneity of the allochthon, approximately parallel to the strike of the Karantrav thrust.     

Pleistocene evolution of the Danube in the Carpathian Basin

The present-day drainage system of the Carpathian Basin originates from the gradual regression of the last marine transgression (brackish Pannonian Sea). The flow directions of the rivers including the Danube, are determined by the varying rates and locations of subsidence within the region. The Danube, which forms the main axis of the drainage network, first filled the depression of the Little Plain Lake and then, further southward, the Slavonian Lake. From the end of the Pliocene, the crustal movements which caused the uplift of the Transdanubian Mountains, forced the Danube to flow in an easterly direction, towards the antecedent Visegrid Gorge, and into the subsiding basins of the Great Plain. Climatic changes during the Pleistocene had the effect of forming up to seven fluvial terraces. The uplift of the mountains is demonstrated by the deformation of the terraces, while the subsidence of the Plains is proven by an accumulation of several hundred metres of sediment. The river only occupied its present position south of Budapest in the latest Pleistocene.     

A Kinematic Model of the Formation of the Sim Trough of the Uralian Foredeep

The structural features and mechanism of the formation of the Sim trough within the Uralian Foredeep, as well as the development of the entire Karatau–Suleiman block, are considered. This wedge-shaped block was subject to lateral extrusion to the north along conjugated strike-slip fault zones under a general latitudinal compression. This factor determined the local meridional compression and latitudinal extension of the block. In the central part of the block, the latitudinal extension was compensated by gradual subsidence, which resulted in the formation of the Sim trough.     

Native gold and companion minerals in the Cenozoic sediments of the Ural Foredeep

Clastic gold in the Cenozoic sediments of the Ural Foredeep is referred to the apron and aureole dynamic types of alluvial placers, which are formed at a distance of 10–30 km from their sources. The gold grains vary appreciably in size and chemical composition of individuals and are characterized by good round-ness and high degree of alluvial refining. It is suggested that endogenic gold occurrences in mountainous regions of the Polar and Subpolar Urals were the main sources of clastic gold grains.     

Socio-geographical transition in the rural areas of the Carpathian Euroregion

Cross-border cooperation is starting to overcome the isolation of frontier regions where interaction under the socialist system was minimal. Change has been particularly apparent in areas where trans-frontier organisations on the ‘Euroregion’ model have emerged. The Carpathian Euroregion is the first exclusively East European example of this approach and it has already made a positive impact in overcoming backwardness in an area where four East European countries were in contact with the Former Soviet Union. The paper outlines the challenge facing the Euroregion – and the national and local governments in the five countries concerned – in providing non-agricultural employment for a large rural population augmented by return-migration from the towns since 1989. Many small farming businesses have been started as a survival strategy but they cannot be economically viable in a market situation. Although most people are satisified with their rural lifestyle, the inevitability of radical consolidation in a future EU context could be politically destabilising if more jobs are not generated in manufacturing and in an expanding tertiary sector. This revised version was published online in July 2006 with corrections to the Cover Date.     

Paleogeography of the Bureya Foredeep (in the Far East) in the Jurassic

Using the standard methods of paleogeographic analysis, small-scale paleogeographic sketch maps of the Verkhnyaya Bureya and Gudzhik depressions of the Bureya Foredeep are compiled for the Pliensbachian, Bajocian-Bathonian, Callovian, and Tithonian ages of the Jurassic. Marine sedimentation settings that existed during the Late Triassic and the major part of the Jurassic are characterized.