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.
Moundlike, globular to hemispherical bryozoan colonies of Celleporina medoborensis sp. nov. are documented from the calcareous organodetrital, slightly marly facies of the Lower Sarmatian (Volhynian) serpulid-microbialite reefs, in the Polupanivka and Ditkivtsi quarries (Medobory Hills), located at the northeastern margin of the Carpathian Foreland Basin (Central Paratethys) in western Ukraine. The colonies of C. medoborensis are multilamellar, often with a subcircular hole and occur together with numerous cyclostome bryozoans (crisiids, tubuliporinids, branching colonies of entalophoroids) as well as schizoporellid and cryptosulid cheilostomes, accompanied by a few macro- and micro-fossil taxa. The combination of morphological characters such as: thick radial ribs in the pseudoporous, variably-shaped area of the ovicell, and one or two small adventitious oral, as well as large vicarious avicularia are the main characteristic features of species. The rich occurrence of the celleporiform colonies of C. medoborensis sp. nov. within the fine-grained calcareous sands of Polupanivka and Ditkivtsi suggests a shallow-water setting and high availability of soft substrates, probably dominated by calcareous algae upon which the bryozoans may have settled in the Medobory reef biota during the Early Sarmatian.
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.
Eksploatacja złóż siarki rodzimej prowadzi do znacznej degradacji środowiska naturalnego. Złoża siarki Basznia i Niemirów znajdujące się na północnym obrzeżu zapadliska przedkarpackiego, na pograniczu Polski i Ukrainy, eksploatowane metodą otworową, w latach 90. ubiegłego wieku zostały zamknięte. Tereny poeksploatacyjne charakteryzują się znacznym przekształceniem mechanicznym i chemicznym gleb oraz degradacją przypowierzchniowych warstw gruntu. Badania geochemiczne próbek gleby z obszaru eksploatacji wskazują na silne zakwaszenie gleby (pH zwykle 2–6) oraz podwyższoną koncentrację Ba, Ca, S i Sr na obszarze poeksploatacyjnym względem obszaru otaczającego.
EN
Native sulphur exploitation leads to strong degradation of natural environment. Sulphur deposits like Basznia and Nemyriv occurring along the northern margin of the Carpathian Foredeep in the Polish-Ukrainian borderland were exploited using method of underground melting by hot water. The exploitation was stopped in the nineties. The sulphur mine areas are characterized by strong mechanical and chemical soil transformations. Geochemical analyses of soil and subsoil material reveal that the anthropogenic changed soils are distinctly acidic (mostly pH = 2–6) and enriched Ba, Ca, S and Sr compared to adjacent forest and agriculture grounds.
The unique Middle Miocene reef belt formed within the Paratethyan realm constitutes at present the Medobory Hills in western Ukraine and northernmost Moldova. Not only is the size of this structure (almost 300 km long) quite unusual, but also the development of peculiar facies and their spatial distribution. Two distinct reef generations appear in Medobory (Late Badenian and Early Sarmatian), both separated by a sharp erosional boundary. Two Upper Badenian calcareous lithofacies dominate – organodetrital and biohermal (with coralline-algae as main framework builders accompanied by a rich invertebrate assemblage). The Lower Sarmatian strata, although megascopically very similar to Upper Badenian ones, differ drastically when studied closely. The main reef components here are serpulids and microbialites, usually with ubiquitous, but taxonomically highly impoverished fauna. Differences in lithofacies and biotic communities between both reef systems unveil open-marine environment during formation of Upper Badenian reefs and a drastic change of conditions at the Badenian/Sarmatian boundary (including emersion and intense weathering). The Early Sarmatian basin was established soon after and highly restricted conditions prevailed in it (e.g. with mesohaline waters and intense evaporation occurring simultaneously); its deposits are the last record of Middle Miocene sedimentation within the Medobory area.
PL
Wzgórza Miodoborów, rozciągające się na przestrzeni niemal 300 km na obszarze zachodniej Ukrainy i północnej Mołdawii, założone są na pasie raf miocenu środkowego, uformowanych w obrębie północno-wschodnich peryferii Paratetydy. Znaczne zróżnicowanie litofacjalne, jak i zmienność zespołów biotycznych wśród utworów rafowych jest rezultatem obecności dwóch generacji raf (późnobadeńskiej i wczesnosarmackiej) oddzielonych wyraźną powierzchnią erozyjną. Wśród wapiennych osadów górnego badenu dominują litofacje organodetrytyczne i biohermalne. Ich głównym składnikiem skałotwórczym są krasnorosty, którym towarzyszą bogate taksonomicznie zespoły bezkręgowców, obejmujące m.in. korale, mięczaki, szkarłupnie. Rafy sarmatu dolnego budowane są przez mikrobiality, w obrębie których występują serpule (i podrzednie mszywioły). Silnie zubożona taksonomicznie fauna zamieszkująca rafy sarmackie zdominowana jest przez mięczaki. Różnice bio- i litofacjalne w obrębie wymienionych generacji raf są efektem drastycznej zmiany warunków sedymentacji, połączonej z emersją i intensywnym wietrzeniem, do której doszło na przełomie badenu i sarmatu w efekcie przebudowy basenu przedkarpackiego. W jej wyniku pełnomorski zbiornik późnobadeński został zastąpiony przez silnie izolowany basen wczesnego sarmatu, zaś powstałe w tym ostatnim osady wieńczą sukcesję utworów miocenu w tej części zapadliska przedkarpackiego.
The Middle Miocene (Upper Badenian) coralline algal reefs of Western Ukraine contain caverns (up to 1 m across) and fissures that are filled by Sarmatian deposits: marly clays, clayey carbonate sand and bioclastic, bryozoan-rich sand. These deposits often contain abundant and very well preserved calcareous benthic foraminifera; agglutinated forms have not been recorded. Foraminiferal tests quite commonly show morphological abnormalities, e.g. twin forms or tests with irregularities in size or shape in last chambers. Each of the three analysed samples is characterized by a different foraminiferal assemblage: Elphidium aculeatum assemblage, Hauerinidae assemblage and Lobatula lobatula assemblage. These assemblages are characteristic for a shallow marine environment. Low taxonomic diversity and high dominance or monospecific foraminiferal assemblages indicate generally a restricted marine environment. It seems that the increasing salinity and very high-energy environment were the most probable factors controlling the composition of the foraminiferal assemblages.
PL
Górnobadeńskie rafy koralowe zachodniej Ukrainy posiadają kawerny o przekroju do 1 m oraz szczeliny, które obecnie są wypełnione osadami sarmackimi – iłami marglistymi i zasilonym piaskiem węglanowym i bioklastycznym, często mszywiołowym. Osady te często zawierają liczne i bardzo dobrze zachowane węglanowe otwornice bentosowe; nie stwierdzono natomiast otwornic zlepieńcowatych. Dość częste są skorupki z morfologicznymi nieprawidłowościami, np. formy bliźniacze albo skorupki z nieregularnością rozmiaru lub kształtu ostatnich komór. Każda z trzech próbek zawiera inny zespół otwornicowy: w pierwszej występuje zespół z Elphidium aculeatum, druga zawiera zespół z Hauerinidae, a trzecia – zespół z Lobatula lobatula. Wszystkie te zespoły są charakterystyczne dla środowiska płytkomorskiego. Niskie zróżnicowanie taksonomiczne i wysoka dominacja lub jednogatunkowe zespoły otwornicowe wskazują na ogólnie ograniczone środowisko morskie; wydaje się, że w takich warunkach najbardziej prawdopodobnym czynnikiem warunkującym skład zespołów otwornicowych było podwyższone zasolenie i środowisko bardzo wysokoenergetyczne.
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.
8
Dostęp do pełnego tekstu na zewnętrznej witrynie WWW
The Late Badenian coralline algae-vermetid reefs and the Early Sarmatian serpulid-microbialite reefs distributed widely in the northeastern and eastern borders of the Carpathian Foredeep Basin contain an excellent bivalve record and show how the bivalve faunas reflected the temporary closure of seaways between the Paratethys and the Mediterranean around 13.3 Ma. within the Late Badenian reefs, 116 bivalve species and three bivalve associations are recognized. After a dramatic change of environmental factors, the Early Sarmatian reefs hosted 12 bivalve species, grouped in four associations. These are thought to have been controlled largely by salinity and to represent decreased and/or fluctuating salinity regimes. An integrated approach, using benthic fauna, sedimentological and isotope data, enabled interpretation of the origin of the serpulid-microbialite reefs. The changes in the palaeogeography of the Paratethys and sea-level oscillations around the Badenian/Sarmatian boundary played an important role in the distribution, extinction and radiation of the bivalves. The definitive closure of the extensive seaway connecting the Paratethys with the Mediterranean caused not only severe extinction of the bivalves inhabiting the sandy facies during the Late Badenian but also the sudden evolution and dispersal of a few opportunistic species that were ancestral forms to Sarmatian taxa. The composition of the bivalve assemblages and the ecological requirements of particular species prove the mixo-mesohaline character of the Sarmatian Sea (30-18[per-mille]) and indicate an eastward decrease in salinity.
Dolomite is a quite common, although usually minor, constituent of the Badenian sulphate deposits of the Carpathian Foredeep Basin. In the autochthonous member of the Wola Różaniecka 7 borehole (SE Poland) which contains well preserved, large anhydritic pseudo-morphs after selenitic gypsum, dolomite constitutes up to 75% of the rock volume, the rest being anhydrite. Dolomites mostly show peloidal clotted microfabrics typical of microbialites and are interpreted as products of microbially induced precipitation and/or dolomitisation at temperatures around 40°C (as interpreted from the d18131813
10
Dostęp do pełnego tekstu na zewnętrznej witrynie WWW
Przedstawiono charakterystykę litologiczną utworów mioceńskich występujących na obszarze Roztocza. Utwory dolnobadeńskie, podewaporatowe występują jedynie we wschodniej części Roztocza i wykształcone są jako piaski i piaskowce kwarcowe, kwarcowo-glaukonitowe i kwarcowo-rodoidowe, rzadziej jako wapienie i margle litotamniowe. Ponad nimi leżą gipsy i wapienie ratyńskie zaliczane do utworów ewaporatowych. Powyżej nich występują górnobadeńskie, nadewaporatowe silnie zróżnicowane litologicznie utwory, m.in. wapienie organodetrytyczne i rodoidowe, wapienie glonowo-ślimakowe, podrzędnie piaski kwarcowe i iły. Przykryte są one przez dolnosarmackie skały węglanowe, m.in. wapienie organodterytyczne, organodetrytyczno-terygeniczne, wapienie serpulowo-mikrobialitowe. Analiza mikrofacji oraz struktur sedymentacyjnych badanych utworów wskazuje na płytkowodne wysokoenergetyczne morskie środowisko sedymentacji, o zmieniającym się jednak w czasie chemizmie wód.
EN
The lithological characteristic of the clastic Badenian deposits of the Roztocze Hills is presented, in the territories of Poland and Ukraine. Generally, the Miocene succession of the Roztocze Hills begins with transgressive quartz, quartz-glaukonite and quartz-rhodolithe sands and sandstones of Early Badenian age, possessing their greatest thickness and limits in Ukraine. Towards the top, the sands pass laterally into marls and coralline algal limestones. Those deposits are overlain by a continuous level of gypsum and/or Ratyń Limestones, included into the Evaporitic-Chemical Beds. Various shallow-water carbonate and terrigenous deposits of Late Badenian age overlie the Evaporitic-Chemical Beds. The terrigenous rocks are represented mainly by quartz sands and sandstones with an admixture of glauconite, siltstone and clay. The biogenic rocks are represented by various shell coquinas and reefal-type deposits. The Miocene succession of the Roztocze Hills is terminated by deposits of Sarmatian age. These are represented by serpulid-microbialite reefs, exposed in the westernmost part of the Roztocze Hills. The microfacies and sedimentary structures of studied rocks point to a high-energy, shallow-water, marine environment with changeable chemical conditions during sedimentation.
The Middle Miocene (Lower Sarmatian = Middle Serravallian) carbonate buildups called “serpulid-microbialite reefs” that occur in the Medobory and Roztocze regions (Paratethys Basin, western Ukraine and southeastern Poland) are composed mainly of calcite precipitates. Skeletal organisms represented by serpulid tubes and bryozoans (in places) are of minor importance and comprise merely a few percent of the rock volume. They are overgrown with micritic peloidal microbialites that are the major reef component. The microbialites and serpulids/bryozoans make together a porous reef framework that is usually filled up with abundant synsedimentary fibrous cements and micritic internal sediments. Other biota is taxonomically impoverished but often rich in individuals and comprises few species of bivalves, gastropods, benthic foraminifers. In places, the serpulid-microbialite limestone masses are incrusted with coralline algae, bryozoans and nubeculariid foraminifers. Bivalve coquinas, bioclastic limestones, breccias and conglomerates are associated with the reefs. The synsedimentary precipitates represented by microbialites and fibrous cements have quite unusual geochemical characteristics. They are composed of Mg-calcite with 5–6 mole % MgCO3 in average with a very high content of strontium (1000–1650 ppm Sr). The precipitates are enriched in heavy oxygen and carbon isotopes. Fibrous cements exhibit the highest values (18O ca. +1.5 [PDB] and 13C 2.8 [PDB]. It is generally believed that in the Early Sarmatian the Paratethys was a brackish basin due to restricted connections to theWorld Ocean. This is indicated by taxonomically poor biotic assemblages that inhabited the basin. On the other hand, however, the predominance of calcitic precipitates (such as microbialites and synsedimentary cements) is indicative of water highly supersaturated in respect to calcite due to high carbonate alkalinity content. Oxygen isotopic composition of the precipitates indicates that the brackish water, in which the reefs originated, had to be enriched in the heavy oxygen isotope due to strong evaporation. The low Mg content in calcite (if compared to modern tropical settings) could be the result of a relatively low precipitation temperature coupled with lower Mg/Ca ratio in Miocene than today, and the elevated Sr content may be indicative of a high precipitation rate resulting from high supersaturation. It seems therefore that the origin of the serpulid-microbialite buildups is related to a peculiar interplay of regional and local controls in the Sarmatian Paratethys. First, the relative isolation of the entire Paratethys basin resulted in the brackish water environment that could be inhabited by taxonomically poor opportunistic biota only and simultaneously enabled blooming of microbial communities. Second, a strong evaporation of the brackish water with high alkalinity content caused a supersaturation in respect to calcium carbonate and consequently a widespread precipitation of calcite (including calcification of microbial mats).
12
Dostęp do pełnego tekstu na zewnętrznej witrynie WWW
Badeńska sukcesja ewaporatowa w otworze Ryszkowa Wola 7 składa się z anhydrytów wykształconych w facji laminowanej oraz brekcjowej. Wartości delta 18O i delta 34S anhydrytów wskazują na morskie pochodzenie jonu siarczanowego. Zespoły otwornicowe w utworach bezpośrednio poniżej poziomu anhydrytowego, a także w obrębie najniższej części anhydrytu, świadczą o redepozycji mikrofauny.
EN
Middle Badenian evaporites of the Carpathian Foredeep basin show a regular spacial pattern of evaporite facies: primary gypsum forming wide sulphate platform (with gypsum sections a few tens of metres thick) occurs in the most marginal, northern part of the Carpathian Foredeep. In more buried, basinward part of the Badenian evaporite basin, the place of primary gypsum is taken by anhydrite (e.g. B. Kubica, 1992) usually 10-30 m thick, and in the narrow axial part of the basin, in local salt basins, halite deposits occur. The depth in halite basins was a few hundred metres (A. Garlicki, 1979), and a part of the salt was deposited through the action of gravity currents (e.g. A. Ślączka, K. Kolasa, 1997). Siliciclastic rocks forming intercalations in halite show the facies variability and sedimentary structures characteristic of turbidites (K. Bukowski,1997). Between the marginal sulphate platform and the axial part a zone occurs where laminated sulphates with sulphate breccia and claystone intercalations occur. The Ryszkowa 7 borehole has been located in the eastern part of the Polish Carpathian Foredeep (Fig. 1). In this part of the foredeep, at the base of the Miocene sequence, thin (20-30 m) transgressive conglomerates, sandstones and claystones occur; they belong to Lower Badenian. Middle Badenian anhydrites that follow are covered by very thick (up to 2,500 m) Upper Badenian and Sarmatian claystones and sandstones (R. Ney et al., 1974). The anhydrite section consists of interbedded laminated and breccia anhydrite (Fig. 2). The anhydrite facies display features characteristic of redeposited sediments. Resedimentation is a relatively common phenomenon observed in modern evaporitic environments and the ancient evaporite sequences. The sulphate originated by precipitation at the air-water interface, with the sulphate particles settling to the bottom as a fine crystal "rain", or by precipitation from the brine body. Subsequently, it could be redeposited in relation to debris flows initiated by the earthquakes. The delta values (delta 18O: 11.26-15.15 promile, delta34S: 20.92-24.18 promile) of anhydrite are shown in Figs. 2-4. They indicate a marine origin of sulphate ion (cf. G. E. Claypool et al., 1980). It is characteristic that the general patterns of changes of delta values of Ryszkowa Wola (the central partof the Carpathian Foredeep) and Borków (the peripheral part) are very similar. Foraminiferal assemblages recorded below anhydrite and in the siliciclastic intercalation in the lowermost part of anhydrite (Pl. I-II) derive from older deposits as well as penecontemporaneous with the deposition of the oldest part of the anhydrite section. Redeposited foraminiferal assemblages related to the Wieliczka salt deposits were earlier found by E. Łuczkowska and J. Rolewicz (1990).
JavaScript jest wyłączony w Twojej przeglądarce internetowej. Włącz go, a następnie odśwież stronę, aby móc w pełni z niej korzystać.