Most western geological surveys, and in particular European Union countries and the USA, focus on public-good science for government, and research to understand earth and environmental processes, in order to supply neutral and independent advice and information about all geoscientific and natural resources issues to the government and society. In contrast, the current draft law on the Polish Geological Agency aims at introducing coherent hydrogeology and geology management as well as implementation of state policy in the field of resources security. Thus, the conclusion that the Polish Geological Agency is an analog of geological surveys, existing in many other developed countries, is absolutely unjustified.
The Hanover declaration (1993) of the mission of a geological survey clearly states that it does not deal with management, but as a government organization it should serve the state authorities and societies by scientific advice and information on natural resources and the environment, and such a mission can be accomplished only by science, methodological competence and research independence. More than a half of the geological surveys in EU countries define themselves as research institutions (Fig. 1), and the scientific production expressed in the ratio ofpublications in JCR journals per staff number in some geological surveys (e.g. ČGS, BGS) is bigger than in the Polish Geological Institute-NRI (Fig. 2) what in part is related to the role played by sendee tasks of the PGI-NRI. The close connections of geological surveys with the scientific research are ignored by adherents of establishment of the Polish Geological Agency.
The paper presents the critical opinion expressed by Osiejewicz (2018b) who supports the view of Legislative Council of26 January 2018 on the draft act on the Polish Geological Agency that the German federal geological survey (Bundesanstalt fur Geowissenschaften und Rohstoffe - BGR) can be considered as an appropriate formula for the Polish Geological Institute - National Research Institute (PGI - NRI). This opinion is groundless and ignores the fact that because of the federal nature of FRG, many tasks of the national geological survey can, and are, accomplished by the state geological surveys only, and cannot be realized by BGR. PGI-NRI in turn accomplishes tasks of both BGR and the state geological surveys and in addition, possesses bigger potential to undertake new tasks.
The Zechstein Limestone of the Bonikowo 2 borehole is composed of limestone with varied dolomite content and is slightly thicker (3.4 m) than other supposed condensed sections in SW Poland. The microfacies (mostly bioclastic wackestones-packstones) are characteristic of open marine limestone deposited in deep shelf environments. The common occurrence of echinoids in all parts of the section, except close to its top, indicates no essential change in sea water salinity. However, the palaeotemperature interpretation of the highest δ18O value of calcite recorded in the Bonikowo 2 borehole (+0.32‰) indicates a temperature of 22.9°C when a δ18O of water = 2‰ is assumed. The δ13C and δ18O curves for calcite and dolomite are similar in shape, and their mean values are similar: +1.8 ±1.5‰ for calcite, respectively, and +1.9 ±2.3‰ and –4.3 ±2.4‰, –3.8 ±4.3‰ for dolomite. There is a recrystallized interval in the lower part of the section with both δ13C and δ18O values reduced. This may be regarded as an aerobic equivalent of the Kupferschiefer. The diversity and abundance of foraminifers is significant throughout the section studied; lagenids prevail, and this is considered to be due to the dysaerobic conditions throughout the duration of deposition of the Zechstein Limestone.
The Badenian section of Anadoly near Kamyanets Podilskyy (Ukrainian Carpathian Foredeep Basin) consists of the Tyras Fm. (gypsum and Ratyn Limestone) and the Ternopil Mb. of the Kosiv Fm. The latter are 5.3 m thick and are composed of dark grey mudstones with limestone intercalations. This study indicates the occurrence of over 54 species of benthic foraminifers and 10 species of planktonics. Benthic foraminifera are represented mainly by calcareous forms; agglutinated tests are very rare. Planktonic foraminifera appear in the upper part of the succession studied. Five benthic foraminiferal assemblages are recognized: A (Elphidium/Lobatula/Astrononion) B (Hauerinidae), C (Cibicidoides/Lobatula), D (Porosononion) and E (Uvigerina/Bulimina). The foraminiferal record indicates deposition in a shallow subtidal environment (20 m depth) of normal marine salinity and temperate waters followed by gradual deepening of the basin to >50 m. Analysis of foraminiferal assemblages indicates that bottom waters were highly oxygenated during deposition of the lower and middle parts of the Anadoly sequence. During deposition of the upper part of the sequence the oxygenation of bottom water gradually decreased, as expressed by a large decrease in the proportion of oxic species and an increase in dysoxic ones. The same set of samples yielded low amounts of palynological organic matter represented by dominant black opaque phytoclasts; bisaccate pollen grains and dinoflagellate cysts are rare. Taxonomically impoverished assemblages of the latter consist of dominant Polysphaeridium and Cleistosphaeridium placacanthum associated with Lingulodinium machaerophorum and a few other taxa. The taxonomically richest assemblage was found in the topmost sample. These changes were interpreted as indicative for increased salinity in the surface water layer, with its maximum in the middle part of the section; the assemblage from the topmost part is characteristic for normal marine salinity.
The Jabłonna Reef, one of the reefs formed in Wuchiapingian time in the western part of the Wolsztyn palaeo-High (SW Poland), is characterized by quite irregular outlines and consists of three separate reef bodies (ca. 0.5–1.5 km2 each; the thickness of the reef complex is usually >60 m). It is penetrated by four boreholes, which show two distinct phases of bryozoan reef development during deposition of the the Zechstein Limestone. The first one occurred early in the depositional history and botryoidal aragonitic cementation played a very important role in reef formation. This phase of bryozoan reef development terminated suddenly; one possible reason was that a relative change of sea level – first a fall and then a rise – disturbed the upwelling circulation. Consequently, bioclastic deposition predominated for a relatively long time until the second phase of bryozoan reef development occurred, but the latter was not accompanied by dubious early cementation. During this second phase, reticular fenestellid bryozoans were predominant. Subsequently, microbial reefs developed and abound in the upper part of the Zechstein Limestone sections. The general shallowing-upward nature of deposition in the Jab³onna Reef area resulted in reef-flat conditions with ubiquitous, microbial deposits, in the central part of the Jab³onna Reef. Then, the reef-flat started to prograde and eventually the entire Jab³onna Reef area became the site of very shallow, subaqueous deposition. Five biofacies are distinguished in the Jab³onna Reef sections: the Acanthocladia biofacies at the base, then mollusc-crinoid, brachiopod-bryozoan, Rectifenestella and at the top, stromatolite biofacies. They represent a shallowing-upward cycle, possibly with some important fluctuation recorded as the distinctive lithofacies boundary, corresponding to the Acanthocladia/mollusc-crinoid biofacies boundary. The 13C curves of the Jab³onna 2 and Jab³onna 4 boreholes permit correlation of the trends in the middle parts of both sections and confirm the strong diachroneity of the biofacies boundaries, with the exception of the roughly isochronous Acanthocladia/ mollusc-crinoid biofacies boundary. The presence of echinoderms and strophomenid brachiopods indicates that until deposition of the lower part of the Rectifenestella biofacies, conditions were clearly stenohaline. The subsequent elimination of stenohaline organisms and progressively poorer taxonomic differentiation of the faunal assemblage are characteristic for a slight, gradual rise in salinity. The taxonomic composition of organisms forming the Jab³onna Reef shows a similarity to reefs described from England and Germany, as well as the marginal carbonate platform of SW Poland. Filled fissures were recorded in the lower part of the Jabłonna Reef. The aragonite cementation recorded in some fissure fillings implies that they originated in rocks exposed on the sea floor and are neptunian dykes.
Skład i zmiany zespołów otwornic pochodzących z najwyższej części utworów podewaporatowych w otworze wiertniczym Busko (Młyny) PIG-1 (głęb. 188–192 m), zlokalizowanym w północnej części zbiornika przedkarpackiego (Paratetyda Środkowa), wskazują, że zbiornik, w którym powstawały osady margliste, był słabo wentylowany, z dużym deficytem tlenowym w wodach przydennych oraz ze środowiskiem eutroficznym w wodach powierzchniowych. Zbiornik ten, o głębokości 50–70 m, wypełniały wody chłodne o zasoleniu typowym dla zbiornika morskiego. Obserwowane w najwyższej części profilu prawie całkowite wyeliminowanie otwornic Uvigerina i zajęcie na krótko zwolnionej niszy przez Fursenkoina acuta (zespół D4c) oraz zdominowanie składu najmłodszego zespołu (D4d) przez tolerującą podwyższone zasolenie Bulimina elongata może jednak wskazywać na znaczne podwyższenie zasolenia w trakcie depozycji najwyższej części utworów poprzedzających depozycję gipsów. Profil gipsów badeńskich w badanym otworze wiertniczym w porównaniu z bardziej brzeżną strefą platformy gipsowej cechuje się redukcją dolnej, autochtonicznej części gipsów oraz specyficznym wykształceniem najniższej jednostki gipsów. W matriksie ilastym występują tam gruzły gipsu bardzo przypominające małe, chaotycznie ułożone blokowe zrosty krystaliczne, określane jako facja szkieletowa gipsów szklicowych, związana w niecce Nidy oraz na Morawach z obniżeniami dna. Wykształcenie profilu gipsów wskazuje na głębsze środowisko sedymentacji niż to stwierdzono w rejonie niecki Nidy.
EN
Composition and changes in foraminiferal assemblages recorded in the uppermost part of the sub-evaporite deposits of the Busko (Młyny) PIG-1 borehole (depth 188–192 m) in the northernmost part of the Fore-Carpathian Basin (Central Paratethys) indicate that the basin, in which marly deposits have originated, was poorly ventilated with a great oxygen deficit in the bottom waters, and was characterised by mainly eutrophic conditions in surface waters. The basin was 50–70 m deep. The waters were cool and of normal seawater salinity, although the recorded (in the uppermost part of the section) almost complete disappearance of Uvigerina foraminifers, occupation (for a short time) of the vacant niche by Fursenkoina acuta (assemblage D4c), and the dominance of Bulimina elongata (tolerant to increased salinity) in the youngest assemblage (D4d) may indicate a considerable increase of seawater salinity during the deposition of the uppermost part of the sub-evaporite strata. The gypsum section is characterised, when compared to the more marginal gypsum sections of the Nida Trough, by a reduction of the lower, autochthonous part of the gypsum section and a specific development of the lowermost gypsum unit. It contains gypsum nodules resembling small, chaotically arranged gypsum intergrowths in the clayey matrix. Such facies is regarded as the skeletal facies of the giant gypsum intergrowth facies of the Nida Trough and Moravia, and is related to depositional lows at the beginning of the gypsum deposition. The gypsum sequence in this borehole indicates a deeper sedimentary environment than inferred for the Nida Trough.
Dolomitisation was the main diagenetic process in the Upper Permian Zechstein Limestone of the Wolsztyn High-dolomite cementation (“over-dolomitisation”) also occurred. The rocks studied usually have a mixed mineralogy and represent a continuous spectrum from pure limestone to pure dolomite. This is due to varying degrees of dolomitisation, dolomite cementation and dedolomitisation. There are two main types of dolomite: replacement dolomite (mostly planar unimodal dolosparite mosaics that are mainly fabric-destructive) and cement dolomite (planar isopachous rims and pore-filling non-planar saddle-dolomite crystals). The timing of dolomitisation and dolomite cementation is difficult to ascertain, but comparing petrographical and geochemical data indicates that the reef carbonates were dolomitised shortly after deposition in a near-surface sabkha/seepage-reflux and then in burial systems. It seems that many of the dolomites gain their present isotopic composition when buried in relatively high-temperature conditions, as shown by low oxygen isotopic ratios ( δ18O as low as –9‰ PDB) and the presence of saddle dolomite. No isotopic support for a water-mixing mechanism is documented.
The Upper Badenian marly shales overlying gypsum and the Ratyn Limestone at Shchyrets, Ukraine, contain moderately to well-preserved benthic (calcareous only) and planktonic foraminifers, and palynofacies dominated by bisaccate pollen grains, presumably transported by wind. Both foraminiferal and dinoflagellate cyst assemblages indicate an open marine environment with normal-marine salinity and cool waters. The palaeodepth was ca. 50 m except for the uppermost part of the section studied, where a distinctive deepening is indicated by the dominance of Uvigerina in benthic foraminiferal assemblages and a high P/B ratio. The water was thermally stratified and the differences between the bottom water and the water column show an upwards-increasing trend. Bulimina and Globocassidulina are the most common and dominant component of benthic foraminiferal assemblages, except for the uppermost part where Uvigerina dominates the assemblage. The composition of benthic foraminifer assemblages and δ13C values of foraminifers indicate nutrient-rich waters and mesotrophic to eutrotrophic environments in surface waters, and low oxygenation at the sea floor in the Ukrainian Carpathian Foredeep Basin during the Late Badenian.
The development of basal Zechstein (Wuchiapingian) strata inSW Polandindicates the existence of a diversified relief inherited after the flooding of the pre-existing depression by the transgressing Zechstein sea. The deeper parts of the basin were the place of development of thin basinal Zechstein Limestone showing sedimentary condensation manifested by bored and encrusted grains and thick evaporites (mostly halite), and in shallow parts Zechstein Limestone reefs followed by thinner evaporite sequences (dominated by anhydrite) occur. The analysis of 3D seismic sections showed that instead of three conventionally recognized evaporite units of stratigraphic potential in the PZ1 cycle, five units occur (from the base to the top: Lower Anhydrite, Lower Oldest Halite, Middle Anhydrite, Upper Oldest Halite, Upper Anhydrite). In a particular place their number may vary from two (Lower Anhydrite at the base of the PZ1 cycle and Upper Anhydrite at the top of the PZ1 cycle) to five. There are two complexes of Lower Anhydrite occurring throughout the platform and basinal zones showing deepening-upward (transgressive) trend. The halite sedimentation in the deepest parts of salt basins began shortly after the deposition of the upper Lower Anhydrite complex while in the sulphate platform areas the sulphate deposition lasted still for a long time. The Lower Oldest Halite deposits occur in the depressions. Between the halite basins, anhydrite platforms occur, and the thickness of anhydrite platform deposits is smaller than it is observed in salt basins. The Upper Oldest Halite in turn is recorded above the anhydrite platform. The two halite units represent different phases of development of halite basins. The Lower Oldest Halite basins are related to the pre-Zechstein depressions, although in some cases their syndepositional subsidence was controlled by reactivation, during the deposition of basal Zechstein strata, of former faults. In turn, the Upper Oldest Halite basins used the accommodation space created due to anhydritization of the Lower Anhydrite deposits composed originally of selenitic gypsum. The 3D seismics evidences that the PZ1 evaporites inSW Polandhave been deposited in far more complex and dynamic system than it was assumed before.
To establish the brine chemistry associated with the evaporites in the Pennsylvanian Paradox Basin of southeastern Utah and southwestern Colorado (USA), the composition of primary fluid inclusions was determined for sedimentary halite from two drill cores, one near the central part of the basin (Shafer Dome No. 1) and one from a more marginal location of the basin (Gibson Dome No. 1). Chemical analysis of halite fluid inclusions was done on six samples from three different evaporite cycles of the Paradox Formation; cycle 10 in the Shafer Dome core and cycles 6 and 18 from the Gibson Dome core. The inclusions that range in size from 2 to 80 microns across, were analyzed using the Petrychenko method. Large inclusions (40 to 80 microns across) that were used for the chemical analyses contain one fluid phase with a carnallite or sylvite daughter crystal. Also reported in this study are fluid inclusion homogenization temperatures for sylvite or carnallite from primary halite crystals in the Gibson Dome core and in Shafer Dome. The relationship between K+ and Mg2+ in chloride rich inclusions corresponds to their proportion in MgSO4-depleted marine waters concentrated to the stage of carnallite deposition. A correlative relationship was observed between K+2+4-rich to MgSO4-poor compositions that have been proposed by other workers. A transition from MgSO4-rich to MgSO4-poor seawater composition may have occurred between Pennsylvanian and Permian times. This paper presents a possible alternate explanation to those already proposed in the literature, that the Paradox Formation mineralogy resulted from an intermediate seawater composition that records the global transition from MgSO4-rich to MgSO4-poor seawater.
Neptunian dykes were recently recorded within the Middle Miocene (Upper Badenian and Lower Sarmatian) Medobory reef complex of the Carpathian Foreland in western Ukraine. The Upper Badenian reefs are cut by a regular, semi-perpendicular network of intersecting fissures that penetrate the Badenian reef limestone down for more than 10 m. The dykes are filled by several generations of Sarmatian microbialites coating the fracture walls and by bedded bioclastic sediment (including foraminifers) which is more important volumetrically. The fissure fillings containing both the Sarmatian material as well as rare clasts of Badenian rocks indicate that the fissures were open during the onset of Sarmatian deposition. They originated following the emergence and fracturing of the Badenian limestones, either due to fault tectonics at basin margins induced by basin subsidence, around the Badenian-Sarmatian boundary, or to gravitational instability of large lithified Badenian reef bodies. Only one phase of fracture opening occurred. The filling of fractures was episodic, with pulses of cementation and microbial growth and sediment injection. Four different foraminiferal assemblages recorded in the neptunian dykes indicate that the process of fracture filling was long-lasting.
The basal Zechstein succession in SW Poland is dominated by breccias and/or conglomerates or extraclast-bearing bioclastic limestones, which were deposited during rapid flooding of the pre-existing intracontinental basin in the early Lopingian (Late Permian). Of these, the boulder-cobble breccias and conglomerates are interpreted as deposited in a rocky shore-zone where density flows and upwelling prevailed. The breccias gradually pass up into bryozoan (or other bioclastics) grainstones. The matrix-supported breccias were deposited as large extraclasts and blocks of Carboniferous rock were rolled down or detached from a cliff and were then either embedded into a carbonate sand or formed a framework supplying voids that could be colonized by tubular encrusting foraminifers. These foraminifers abound in all basal Zechstein facies (except in the debris-flow deposits) and are attributed to Palaeonubecularia. The associated faunas include other foraminifers (uniserial and hemigordiopsids), bryozoans, brachiopods, bivalves, gastropods, and microbial deposits. The prolific growth of tubular encrusting foraminifers has resulted from nutrient supply from the basin by upwelling. Botryoidal aragonite cements (also interpreted as due to upwelling) also characterize the basal Zechstein strata, although they were previously reported only from the upper Zechstein Limestone. The ẟI3C values of the basal Zechstein deposits show small variation and oscillated around 4.0%o, suggesting that these deposits are younger than the Kupferschiefer.
The Kupferschiefer (T1) records a period of basin-wide euxinic conditions, and is thus considered an excellent time-marker in the Zechstein (Lopingian) basin. Previous studies indicated that both the Kupferschiefer and Marl Slate and the overlying Zechstein Limestone (Magnesian Limestone) show remarkable changes in carbon isotopic composition towards higher 131313131313
Przedstawiono charakterystykę litologiczną utworów mioceńskich występujących na Roztoczu i terenach sąsiednich (zachodnia Ukraina). Utwory dolnobadeńskie rozpoczynają się transgresywnymi piaskami i piaskowcami kwarcowymi; w wyższej części obocznie przechodzą w margle i wapienie litotamniowe. Powstały w płytkowodnym, wysokoenergetycznym morskim środowisku sedymentacji, o zmieniającym się w czasie chemizmie wód. Środkowobadeński gips pierwotny tworzy szeroką brzeżną platformę siarczanową; w trakcie jego depozycji następowały znaczne wahania składu chemicznego solanek. W płytszych częściach zbiornika na gipsach występują utwory wapienia ratyńskiego, związane genetycznie z transgresją morską. W późnym badenie obszar Roztocza był strefą tranzytową dla materiału bioklastycznego i terygenicznego, w jej obrębie odbywało się przemieszczanie materiału ziarnowego związane z falowaniem i prądami wywołanymi przez falowanie oraz z ruchami masowymi. Węglany dolnosarmackie Roztocza cechują się nietypowym wykształceniem facjalnym oraz ubogim składem taksonomicznym organizmów, wskazującym na anomalne warunki środowiskowe – obniżone zasolenie wody i silne jej przesycenie względem węglanu wapnia.
EN
Lithological characteristics of Middle Miocene strata of the Roztocze region (SE Poland and western Ukraine) is summarized. The Lower Badenian sequence begins with transgressive quartz sands and sandstones that subsequently are passing laterally into marls and coralline algal limestones. They originated in shallow-water, high-energy marine environment. The chemistry of waters at that time as well as during subsequent gypsum sedimentation fluctuated quite considerably. Middle Badenian gypsum deposits build a wide marginal sulphate platform. In shallower parts of the basin the Ratyn Limestone deposits cover gypsum; they are related genetically to new marine transgression. During the Late Badenian the Roztocze region was a transit zone for bioclastic and terrigenous material, and the grainy material was transported owing to waves and wave-generated currents as well as mass movements. The Lower Sarmatian carbonates of Roztocze show a typical facies and poor taxonomic composition of fossil assemblages that indicate abnormal environmental conditions – decreased water salinity and its oversaturation in respect to calcium carbonate.
The paper summarizes the results of various laboratory studies of core material, including porosity, permeability, lithological-facies and structural and textural characteristics of more than 1,000 samples of Mesozoic and Palaeozoic rocks. The petrophysical parameters of siliciclastic and carbonate rocks are analysed for the total of samples representing different lithologies (limestones vs. sandstones) as well as for particular stratigraphic intervals (Upper and Lower Cretaceous, Upper Jurassic, Middle and Lower Jurassic, and Palaeozoic). The terrigenous rocks with intergranular porosity and fracture-cavernous carbonate rocks of reefal facies form the best reservoir rocks within the Mesozoic. The terrigenous rocks of fractured and fractured-porous type that are controlled by the fault-block tectonics provide the best Palaeozoic and Ediacaran reservoirs.
Molecular composition of natural gases accumulated in autochthonous Miocene strata of the Polish and Ukrainian Carpathian Foredeep is dominated by methane, which usually constitutes over 98 vol%. Methane was generated by the carbon dioxide reduction pathway of microbial processes. Ethane was generated both during microbial and thermogenic processes ("oil window") and propane at the initial stage of the low-temperature thermogenic processes, and also by the microbial processes. The rhythmic and cyclic deposition of Miocene clays and sands as well as the vigorous generation of microbial methane caused that the gas produced in claystone beds was accumulated in the overlaying sandstones, and capped, in turn, by the succeeding claystones. Such generation and accumulation system of microbial gases gave rise to the formation of multi-horizontal gas fields. Analysis of the distribution of immature humic dispersed organic matter in the Upper Badenian and Lower Sarmatian sequences indicates that it is practically homogeneous. A migration range of microbial gases was insignificant and locations of their accumulations would depend only on the existence of proper type of traps (compactional anticlines situated above basement uplifts, sealed by the Carpathian Overthrust and/or by faults; stratigraphic pinching out and stratigraphic traps related to unconformities). Another situation is encountered in the south, beneath the Carpathian Overthrust. The thickness of the autochthonous Miocene strata in this area is more than 1,500 metres. Geochemical studies reveal that from a depth of 2,500 metres starts the process of low-temperature thermogenic hydrocarbon generation (“oil window”). At greater depths, more than 7,500 metres, within the autochthonous Lower Miocene basin only the high-temperature methane ("gas window") could be produced and accumulated.
This thematic issue of Annales Societatis Geologorum Poloniae contains a set of papers presenting results of a special research project entitled "Petroleum exploration prospectives and hydrocarbon potential of the Miocene strata and Mesozoic–Palaeozoic basement in the borderland area of Poland and Ukraine", led by research teams from the AGH University of Science and Technology in Kraków and the Polish Geological Institute – National Research Institute in Warsaw. The objective of this paper is determination of the geological and geochemical conditions, 1-D and 2-D modelling of petroleum processes and petroleum systems and their influence on the prospectives of hydrocarbon exploration of the Miocene strata in the Polish and Ukrainian Carpathian Foredeep and its Palaeozoic–Mesozoic basement. In particular, a coherent model of geological structure of the area, based both on the synthesis of the earlier published data and on new results of palynological studies of the Upper Precambrian and Lower Palaeozoic, is given. New data on microfacies of the Upper Jurassic and Lower Cretaceous strata and on sedimentology, geochemistry and micropalaeontology of the Middle Miocene rocks are presented.
The Gorzów Block (West Poland) occurs in the transition zone between the PZ1 sulphate platform and the Na2 basin. In contrast to the western part of the Southern Permian Basin where the Z1 halite (Oldest Halite Na1) is normally restricted to the peripheral subbasins located south of the main basin, in Poland it occurs both in the basin centre and in the former basins of the Lower Anhydrite within the marginal sulphate platform complex, where halite sequences are thick and may have originated in a deep-water setting. The Na1 deposits have been considered so far to be LST deposits both in the marginal sulphate platform facies as well as in the basin centre. Brine salinities (and the minerals they precipitate) are controlled by brine residence times in the basin, and these are determined primarily by the absolute and the relative rates of water flow into, and brine flux out of the basin (Kendall, 2010). Thus sea-level rise in the Boreal Sea could have resulted in the increase of the brine residence times in the Zechstein basin and the deposition of more saline evaporites. Consequently, the Oldest Halite in the basin centre in Poland is regarded as the TST deposit.
The stable oxygen and sulphur isotope ratios of 52 anhydrite samples from three Zechstein anhydrite units (Lower Anhydrite, Upper Anhydrite and Basal Anhydrite) of West Poland show d18O values vs. VSMOW in the range of 9.4 to 15.5% (mean of 12.6 š1.3%), and d34S values vs. VCDT between 9.6 to 12.6%o (mean of 11.4 š0.6%o). A generally uniform distribution pattern of both isotopic values throughout the section, although with some random variation, implies that sulphate ions were sufficiently supplied and the basin was open during sulphate deposition. There is a slight stratigraphic differentiation of both the d18O and d34S values: the highest mean values are shown by the Upper Anhydrite and the lowest average values occur in the Basal Anhydrite. The correlation between d18 O and 8 S values is statistically significant only in case of the Basal Anhydrite. A wide range of oxygen isotopic ratios (from 11.6 to 25. l%o), with only several samples having d18O values that fall within the range of late Permian seawater, have been recorded in anhydrite cements and nodules that occur in the Main Dolomite rocks. Sulphur isotope ratios of anhydrite cements (range of 7.6 to 12.9%o, average of 10.7 š1.4%o) tend to reflect the late Permian sulphur isotopic signature of sulphate in seawater. The higher ranges of d18O and d34S values of anhydrite cements and nodules in the Main Dolomite compared to the underlying and overlying anhydrites are due to diagenetic resetting. The conversion of gypsum to anhydrite (often very early and under negligible cover) evidently did not affect the primary marine stratigraphic sulphur isotope composition of the sulphate deposits.
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