Analysis of previously available stratigraphic data coupled with the re-interpretation of seismic profiles calibrated by boreholes has allowed the construction of a new tectonic model of evolution of the Gdów "embayment" – a tectonic re-entrant located along the Carpathian front east of Kraków (southern Poland). This model shows that the main phase of localized fault-controlled subsidence took place in the Early Badenian and was associated with deposition of the locally overthickened Skawina Formation. Also, deposition of evaporites of the Wieliczka Formation seems to have been tectonically controlled by local basement faulting. Supra-evaporitic siliciclastic deposits have developed as a result of overall north-directed sediment progradation from the eroded Carpathian belt towards the Carpathian Foredeep. During the final stages of development of the Carpathian fold-and-thrust wedge the previously subsiding Gdów "embayment" area was uplifted and basement faults were reactivated either as reverse faults or as low angle thrust faults. Along the leading edge of this inverted structure a triangle zone developed, with backthrusting along the evaporitic level. As a result, overthickened evaporites, formed in local tectonically-controlled depressions within the area of the Gdów "embayment" area have been strongly folded and internally deformed Trailing edge of the Carpathian fold-and-thrust belt between Kraków and Tarnów has been subjected to intense studies because of its control over rich deposits of rock salt (Wieliczka and Bochnia salt mines) and hydrocarbon accumulations. In vicinity of Gdów, Carpathian orogenic front in the area south-east of Kraków recedes to the south, forming a "bay" or "embayment" filled with the Miocene deposits of the Carpathian foredeep basin. Over decades, numerous tectonic models of the Gdów "embayment" have been published. Originally, sedimentary infill of the "embayment" was identified as the Lower Badenian sub-evaporitic (Skawina Beds), with remnants of the Upper Badenian foredeep evaporites only locally preserved at the surface or shallow subsurface. Later, although without sufficiently presented micropalaeontological evidences, new models have been proposed that assumed dominance of the supra-evaporitic Machów Formation (Chodenice and Grabowiec Beds). Analysis of available stratigraphic data coupled with interpretation of good quality seismic profiles calibrated by deep wells allowed for construction of a new tectonic model of evolution of the Gdów "embayment". Under this model, main phase of localized fault-controlled subsidence took place in Early Badenian and was associated with deposition of locally overthickened Skawina Formation. Also deposition of evaporites of the Wieliczka Formation was locally tectonically controlled, similarly to earlier models by Garlicki (1971). Supra-evaporitic siliciclastics have developed as a result of an overall north-directed sediment progradation from the eroded Carpathian belt towards the Carpathian foredeep. During final stages of development of the Carpathian fold-and-thrust wedge previously subsiding Gdów "embayment" area was uplifted, basement faults have been reactivated either as a reverse or low angle thrust faults. Along the leading edge of such inverted structure a triangle zone developed, with backthrust formed along the evaporitic level. As a result, overthickened evaporites, formed in local, tectonically-controlled depressions present within the Gdów "embayment" areahave been strongly folded and internally deformed. Analysis of previously available stratigraphic data coupled with the re-interpretation of seismic profiles calibrated by boreholes has allowed the construction of a new tectonic model of evolution of the Gdów "embayment" – a tectonic re-entrant located along the Carpathian front east of Kraków (southern Poland). This model shows that the main phase of localized fault-controlled subsidence took place in the Early Badenian and was associated with deposition of the locally overthickened Skawina Formation. Also, deposition of evaporites of the Wieliczka Formation seems to have been tectonically controlled by local basement faulting. Supra-evaporitic siliciclastic deposits have developed as a result of overall north-directed sediment progradation from the eroded Carpathian belt towards the Carpathian Foredeep. During the final stages of development of the Carpathian fold-and-thrust wedge the previously subsiding Gdów "embayment" area was uplifted and basement faults were reactivated either as reverse faults or as low angle thrust faults. Along the leading edge of this inverted structure a triangle zone developed, with backthrusting along the evaporitic level. As a result, overthickened evaporites, formed in local tectonically-controlled depressions within the area of the Gdów "embayment" area have been strongly folded and internally deformed
Rock salt occurs in Poland (Central Europe) in two salt-bearing formations of upper Permian (Zechstein) and Neogene (Middle Miocene, Badenian Stage) age, while potash salts are only of Permian age. The total resources of rock salt are >>gt; 106 ´ 109 Mg, predominantly from the Zechstein (> 81 * 109 Mg of anticipated economic resources in 15 documented salt deposits of both stratiform and diapir types). They are now exploited in two underground salt mines and two solution mines that produced in 2008 over 3 ´ 106 Mg of rock salt, mainly from the diapirs. The most perspective future management of these rock salt deposits are as safe underground cavern stores for oil and gas (currently two of these exist, and one is in progress) and depositories. The Badenian deposits (stratiform and stratiform-folded), exploited in the past millennium, occur in a limited area of Southern Poland and are now only of historical-touristic value. Potash salts, quite common within the Zechstein evaporite complexes, are documented in a single salt diapir in Central Poland (resources of over 72 * 106 Mg, with minimal and accidental exploitation of carnallite and kieserite) and in sulfate horizons accompanying the rock salt in Northern Poland (four deposits of polyhalite with resources of ca. 0.67 * 109 Mg). Because of low market prices of potash products offered by neighbouring countries the future management of national potash salt resources seems to be non-economic.
The geochemical data and the study of fluid inclusions in primary halite are invaluable sources of saline basin information. Most of the previous analyses of salt from the Carpathian area have been obtained by studying the halite samples collected from depths not exceeding 1000 m (i.e., from salt mine outcrops or boreholes). In this article, for the first time, we present the results of samples obtained from a deep well where salt occurs below the frontal orogenic wedge at a depth of ~5000 m. The salt core’s petrological studies showed, quite unexpectedly, the presence of the chevron relics, typical for primary halite. Their geochemical data and fluid inclusion study can be used to reconstruct the environment of the salt sedimentation. The bromine, strontium, and rubidium content values indicated that primary brines were of marine origin, and salts may have undergone partial dissolution and redeposition under lower salinity water inflows. The main ions’ (K, Mg, SO4) ratios in the fluid inclusions were typical for those of the Badenian brines collected from the Carpathian Foredeep’s eastern part. Compared with modern seawater’s chemical composition, this brine contained a slightly lower content of sulfate ions. This was associated with evolutionary changes occurring in the contents of sulfate ions during the Cenozoic.
Fluid inclusions in halite are widely used in research to determine the conditions of sedimentation in salt basins and reconstruct the chemical composition of seawater during a specific geological period. However, previous preliminary studies of the genetic types of inclusions, considered in the present research project, have not received due attention. Consequently, we decided to take into account the main distinguishing features of fluid inclusions in halite, belonging to various genetic types. The ultramicrochemical analysis (UMCA) method is one of the several methods that are used for the quantitative determination of the chemical composition of the primary fluid inclusions in halite. We have upgraded that technique, and that allowed us to reduce the analytical error rates of each component determination. The error rates were calculated in the study of Ca-rich and SO4-rich types of natural sedimentary brines.
The most abundant benthic foraminifers recorded in the Wielician salt-enclosed xenoliths are: Bulimina spp., Uvigerina spp., Valvulineria complanata , and Cibicides pseudoungerianus . The predominant taxon in the planktonic assemblage is Globigerina bulloides with a median 98.9% in biozone IIC and 89.1% in the later IID. The IIC assemblage differs from the IID one in both taxon composition and abundance. The most pronounced differences are those revealed by Valvulineria complanata counts, number of benthic taxa and the planktonic/benthic (P/B) ratio. Pseudotriplasia minuta (one of the Wielician index taxa) occurs only in the IID biozone, present in 16 among 28 samples. There is a noticeable difference in surface sculpture morphology pattern in the predominant Bulimina and Uvigerina taxa in the IIC versus the IID biozones. There are smooth ( Bulimina elongata ) and weakly striate ( Uvigerina semiornata plexus) forms in the IIC biozone, followed by heavily costate ( Bulimina striata ) and spinose-pustulate ( Uvigerina orbignyana plexus) forms in the IID. Globigerina druryi and G. decoraperta – the CPN 8 planktonic index taxa – had not been found in the material studied. Globigerinita uvula is unusually common in the samples studied. The samples analysed display an abundance of Globigerina bulloides typical of the sub-evaporite Wielician. Hence the studied Wielician stratotype area supports the thesis of the Globigerina bulloides Acme as the valid name designation for the substage.
The halogenesis of the Messinian Tuz Gölü Basin corresponds to the sulfate type and the magnesium sulfate subtype. Compared to the Messinian Sea brines, they have a slightly higher [Na+] concentration, which is 96.6–116.4 g/L, and a much lower [K+] concentration, ranging from 0.1 to 2.35 g/L. During salt sedimentation, the [Mg2+] concentration ranged from 6.1 to 14.0 g/L, and the [SO42−] concentration from 18.2 to 4.5 g/L. Physical–chemical reactions in the basin’s near-surface and bottom waters during the suspension of halite deposition had a decisive influence on the significant reduction of [SO42−] sedimentation brines. During these periods, there was an intensive influx of Ca(HCO3)2 into the sedimentation basin and the formation of glauberite layers. The formation of the glauberite resulted from the slow dissolution of pre-deposited finely dispersed metastable minerals—gypsum, sodium syngenite, or mirabilite. In fluid inclusions in the halite, the sulfate minerals being allogenic crystals of calcium sulfate, are represented by gypsum, bassanite, and anhydrite. Additionally, as the other sulfate minerals, glauberite, anhydrite, and thenardite are found within halite crystals. Sharp fluctuations in daytime air temperatures characterized climatic indicators of the summer period in the Tuz Gölü region: 15.6–49.1 °C. In the spring or cool summer–autumn period, the daytime air temperature in the region ranged from 15.7–22.1 °C, and in late spring and early summer, it ranged from 20.6 °C to 35.0 °C. During some periods, the Tuz Gölü halite crystallized at 61.8–73.5 °C. The extreme high-temperature crystallization regime at the bottom of the salt-bearing basin was achieved due to the emergence of a vertical thermohaline structure. The “greenhouse effect” in the Tuz Gölü was established only briefly but was periodically renewed due to the influx of “fresh” waters.
Seismic data and core from the shallow cartographic Pilzno P-7 borehole were used to construct a new model of the Carpathian orogenic front between Tarnów and Pilzno, in the Pogórska Wola area (southern Poland). The most external, frontal thrust of the orogenic wedge (the Jaśniny structure) was identified as a syn-depositional fault-propagation fold detached above the Upper Badenian evaporites. Its formation was controlled by the presence of mechanically weak foredeep evaporites and by the morphology of the sub-Miocene Meso-Paleozoic foreland plate (Jaśniny and Pogórska Wola palaeovalleys). The frontal zone of the Carpathian orogenic wedge (the Skole thrust sheet and the deformed foredeep deposits of the Zgłobice thrust sheet) is characterized by significant backthrusting of the foredeep succession towards the south, and by the presence of a triangle zone, with strongly deformed Upper Badenian evaporites of the Wieliczka Formation in its core. The triangle zone was formed during the latest thrusting movements of the Carpathians. An indication of the existence of the triangle zone in the vicinity of Dębica has also been provided by reinterpretation of the archive regional geological cross-section. The youngest foredeep deposits, brought to the surface above the backthrust, have been dated as Sarmatian (NN7 nannoplankton zone), which indicates that the latest thrust movements within the frontal Carpathian orogenic in the vicinity of Tarnów–Dębica took place approx. 11–10 million years ago. Thermochronological studies (AFT and AHe) indicated that the foredeep succession drilled by the Pilzno P-7 borehole has not been buried deeper than 1.5–2 km, which is compatible with reconstruction based on the seismic data.
Pochodzenie badenskich soli basenu wschodnioslowackiego na podstawie analizy cieklych inkluzji
Chemical composition of the brines of primary fluid inclusions in sedimentary halite (from the boreholes: P-2, P-3, P-6, P-7 and P-8) of the Badenian evaporite of the Zbudza Fm. from East Slovakian basin indicates that the basinal brines belong to the Na-K-Mg-Cl-S0 4 type. The ratios of K1, , and SO4 ions are practically the same as they were in the Badenian seawater. Taking into account the information on the chemical evolution of seawater in the Phanerozoic (Kovalevich et a l, 1998) and the calculations of this evolution for the Cenozoic (Zimmermann, 2000) it is suggested that the Badenian seawater was characterized by the reduced contents of Mg (by approximately 20%) and SO4 - (by approximately 40%) in comparison with the recent seawater. The postsedimcntary recrystallization of salts occurred under the effect of buried brines, which inherited their composition from the primary basinal brines. The intensive recrystallization of salts occurred during the tectonic movements.
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