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EN
The D sequence, Upper Oligocene formation is the main target for petroleum exploration and exploitation activities at GAO field in Cuu Long basin. The study primarily uses well log and core samples data from exploration wells in the area to investigate the lithofacies and depositional environment. Shale, sandstone and volcanic material were identified in the gamma ray log. Base on variations in lithology as indicated by well log response, the D sequence can be divided into three members (D1, D2, and D3 subsequences),which were deposited in fluvial to lacustrine environments. The shapes of the gamma ray signature of D2 sub-sequence are serrated funnel, bell and cylindrical reflected sediment deposited in a mouth bar and a distributary channel environment. Sedimentary structure characterized by parallel ripple cross-bedding, with occasional weak cut cross-bedding or small lenticular features. Meanwhile, sediments of D1 and D3 sub-sequences were deposited in a distal lacustrine environment, characterized by saw tooth features, indicating thick layers of lacustrine shale interbedded with thin shore face sand layers.
EN
The complex of freshwater carbonates at Čerená Hill in northern Slovakia was investigated. The facies recognised are mainly represented by a laminated crust, micritic limestone and phytoclastic boundstone and subordinately by moss boundstone and carbonate-siliciclastic mud. The alluvial sediments present at the base of the complex indicate that it was deposited within a flat stream valley at the foot of the Low Tatra Mts. The growth of the carbonates was controlled by the supply of deep-circulation water, containing geogenic CO2, and its outflow to the marshy floodplain. This area was occasionally invaded by surface stream water, resulting in modification of the sedimentary facies, accompanied by a slight differentiation of the geochemical data (δ13C values and CaCO3 content). The U-series and palaeomagnetic data collectively show that the growth of the spring-related carbonate complex commenced between ca. 300 ka and persisted until 200 ka. Deposition during the warm interglacial phases of the Pleistocene is assumed; this is supported by the presence of a malacofauna assemblage, and a high contribution of calcified floral remains in a part of the studied sediments. Post-sedimentary modifications, mainly mass-wasting processes, resulting from the incision of adjacent valleys, shaped the area of Čerená Hill after it was cut off from a deep-water supply.
EN
In the northern Lublin region, the Eocene amber-bearing association has been recognized. It is a group of clastic deposits in which amber crumbs are scattered, and the characteristic feature of the association is the content of glauconite. The sedimentological and lithofacies studies allowed determining the conditions necessary for amber deposition. Accumulation of amber-bearing sediments took place in the Middle and Late Eocene. The Upper Eocene formations in this area occur in isolated patches. Amber accumulations are found in marine sediments associated with regressive facies, usually in depressions of the Cretaceous basement. Understanding the correct distribution of amber in the sediment and determining the dynamics of the Eocene sedimentary basin in the Lublin region have a practical aspect, and are the basis for developing the characteristics of the geological economic conditions for the occurrence of amber-bearing deposits. The recently drilled boreholes confirmed amber resource prospectivity in the Lubartów area and the recognition of new deposits with amber reserves.
EN
The Başkale Basin is located in the easternmost part of Türkiye, within a tectonically active area, and located at the intersection of Europe, Asia and the Middle East. In this study, the Dereiçi travertines, one of the most important products of neotectonism in the basin, were investigated sedimentologically, mineralogically and geochemically. To understand the neotectonic evolution of the travertine succession, the sequence was studied from bottom to top as regards morphology, lithofacies and U/Th dates. Crystalline crust, coated gas bubbles, shrub, paper-thin raft and palaeosol lithofacies have been detected in the Dereiçi travertines, which are morphologically of layer type, two ridge types and terrace type. The Dereiçi travertines commenced to precipitate at the intersection of the Işıklı and Ilıcak faults at 255.56 ±9.01 ka, and their deposition continues today. Travertine deposition paused twice between 198.31 ±18–143.07 ±1.5 ka and 96.73 ±8.34–61.59 ±5.4 ka, when palaeosol development took place. According to field and laboratory studies, the Dereiçi travertines developed under climate and tectonic control. The Işıklı and Ilıcak faults played active roles in the development of the travertines. As the travertine ages are linked to movement on both faults, the age of the Işıklı Fault should be 255.56 ±9.01 ka or earlier, and that of the Ilıcak Fault should be 143.07 ±1.5 ka or earlier.
EN
Identification of volcanic lithofacies is critical for reservoir exploration and a major difficulty in China's Liaohe oil field. In this paper, we present a fractal analysis method for identifying volcanic facies by estimating the fractal dimension of logging data. The fractal properties of lithofacies logging curves are explored, as well as the categorization scheme of volcanic lithofacies in the eastern sag of the Liaohe basin. Five logging curves impacted by volcanic lithofacies from four wells in the Liaohe basin's eastern depression were chosen. The Box-counting dimension is used to develop a logging lithofacies identification criterion. Furthermore, we calculated the fractal dimension of logging curves using box-counting dimension methods.
PL
Głównym celem monografii jest odtworzenie historii depozycji i rozwoju facjalnego utworów górnej jury i dolnej kredy, występujących w podłożu zapadliska przedkarpackiego, w oparciu o dostępne dane z otworów wiertniczych oraz sejsmikę 3D. Rejon badań usytuowany jest w środkowej części przedgórza Karpat, pomiędzy miastami Dąbrowa Tarnowska na północnym zachodzie i Dębica na południowym wschodzie. Nowe dane, uzyskane w roku 2015, w postaci zdjęcia sejsmicznego 3D, jak również informacji z głębokiego otworu O-1 przewiercającego pełen profil utworów mezozoiku, pozwoliły na znacznie lepsze rozpoznanie i udokumentowanie wielu szczegółów budowy geologicznej tego, dotąd słabo rozpoznanego, rejonu. Sedymentacja badanych utworów węglanowych przedgórza Karpat w epokach późnojurajskiej i wczesnokredowej odbywała się w strefie szelfowej północnego, pasywnego brzegu oceanu Tetydy. Cechą charakterystyczną utworów górnej jury jest ich duże zróżnicowanie facjalne, wynikające głównie z obecności rozbudowanych kompleksów biohermowych oraz pakietów warstwowanych osadów marglisto-wapiennych. W rozdziale 2 przedstawiono budowę geologiczną rejonu badań, uwzględniając wszystkie piętra strukturalne, rozwój litologiczny utworów poszczególnych jednostek, stosowane podziały litostratygraficzne i regionalne ramy paleogeograficzne. W rozdziale 3 szczegółowo omówiona została historia badań oraz aktualny stan rozpoznania kompleksu węglanowego górnej jury i dolnej kredy przedgórza Karpat. Rozdział 4 zawiera charakterystykę litologiczną badanych utworów węglanowych z podziałem na jednostki litostratygraficzne. Charakterystyka ta opracowana została na podstawie analizy cech makroskopowych dostępnego materiału rdzeniowego oraz profilowań geofizyki otworowej. Zamieszczone profile litostratygraficzne wybranych głębokich otworów wiertniczych z obszaru badań lub jego bliskiego sąsiedztwa dokumentują obecny stan wiedzy na temat litostratygrafii i rozwoju facjalnego utworów górnej jury i dolnej kredy. W rozdziale 5 przedstawiono charakterystykę mikrofacjalną i mikropaleontologiczną badanych utworów węglanowych, jak również przeprowadzono dyskusję dotyczącą możliwości określenia zasięgu wiekowego poszczególnych wydzieleń litostratygraficznych w oparciu o wyniki wieloletnich badań oraz dane literaturowe. W rozdziale 6 zaprezentowano wyniki analizy obrazu sejsmicznego, wykonanej w oparciu o wybrane atrybuty sejsmiczne. W ramach pracy omówiono następujące atrybuty: RMS Amplitude, Envelope, Instantaneous phase, Dominant frequency, Instantaneous bandwidth, Apparent polarity, Relative acoustic impedance, First derivative, Iso-frequency component, Time gain, Chaos, Variance (Edge method), Local flatness. Przeprowadzona analiza pozwoliła na uzyskanie dodatkowych istotnych informacji odnośnie wykształcenia litologicznego i rozprzestrzenienia utworów poszczególnych ogniw litostratygraficznych, jak również dała możliwość uszczegółowienia lokalizacji dyslokacji. Na podstawie interpretacji zapisu sejsmicznego w obrębie badanego kompleksu skalnego udokumentowano również występowanie niezgodności kątowych, stref zaburzeń i deformacji związanych z tektoniką synsedymentacyjną oraz przypuszczalnych osadów spływów grawitacyjnych. W rozdziale 7 zamieszczono przekroje litofacjalne, skonstruowane wzdłuż wybranych przekrojów sejsmicznych, prezentujące przestrzenny rozkład i wzajemne relacje pomiędzy utworami poszczególnych ogniw litostratygaficzych. W rozdziale 8 przeanalizowano rozmieszczenie kompleksów biohermowych górnej jury względem morfologii podłoża jury. Analiza rozmieszczenia wykartowanych na podstawie zapisu sejsmicznego budowli organicznych, należących do serii wielkich bioherm gąbkowo-mikrobialnych, wskazuje na dwa główne obszary ich występowania, tj. rejon NW (kompleks biohermowy „N”), w którym występuje dosyć rozległy kompleks biohermowy, a jego dokładny zasięg jest trudny do ustalenia ze względu na późniejsze procesy regionalnej dolomityzacji oraz rejon centralny (kompleks biohermowy „S” w okolicach otworu O-1), w którym stwierdzono kompleks kilku wysokich budowli o dosyć stromych krawędziach. Rozdział 9 poświęcony jest zagadnieniu historii depozycyjnej późnojurajsko-wczesnokredowego basenu sedymentacyjnego przedgórza Karpat oraz omówieniu roli najważniejszych czynników wpływających na rozkład facji w obszarze badań. Wykazano, że cechą charakterystyczną znacznej części osadów jurajskich jest silnie diachroniczny charakter rozprzestrzenienia poszczególnych facji, uwarunkowany głównie paleogeomorfologią dna zbiornika sedymentacyjnego, jak również czynnikami lokalnymi, związanymi z tektoniką synsedymentacyjną. Seria gąbkowo-globuligerinowa, rozpoczynająca profil utworów górnej jury i reprezentująca najgłębszy etap sedymentacji w warunkach otwartego szelfu, cechuje się stosunkowo dużą jednorodnością wykształcenia na całym obszarze przedgórza. Kompleks biohermowy „S” rozwinął się w nadkładzie elewowanej strefy, złożonej z kilku mniejszych elementów tektonicznych, natomiast kompleks biohermowy „N” wykształcił się na rozległej, wyniesionej części strefy zrębowej, gdzie w podłożu występuje jeden główny blok tektoniczny. Intensywnie rozwijające się kompleksy biohermowe „N” i „S” wywierały coraz większy wpływ na dalszy rozwój sedymentacji osadów górnej jury w badanym rejonie, dostarczając jednocześnie materiału dla osadów redeponowanych w głębsze partie zbiornika w wyniku podmorskich spływów grawitacyjnych. W strefie przylegającej od SE do kompleksu biohermowego „S”, na profilach sejsmicznych dostrzegalny jest charakterystyczny, wysokoamplitudowy zapis obejmujący cały pakiet refleksów sejsmicznych o zmiennych kątach upadów. Częste zmiany polarności, dostrzegalne w obrębie tej strefy w odtworzeniu atrybutu Apparent polarity, podobnie jak i skrajnie zmienny zakres wartości atrybutu Relative acoustic impedance, świadczą o silnym zróżnicowaniu litologicznym tego kompleksu skalnego. W tytonie, w trakcie sedymentacji utworów serii koralowcowo-onkolitowej, nastąpiło wyraźne ujednolicenie warunków sedymentacji na całym obszarze przedgórza Karpat, związane głównie z zanikiem paleomorfologicznego zróżnicowania powierzchni dna morza. Przypuszczalnie w tym samym czasie miał miejsce kolejny etap reaktywacji dyslokacji, o czym świadczy powierzchnia niezgodności kątowej, i związane z nią efekty erozji osadów starszych. Rozprzestrzenione na całym obszarze badań utwory serii muszlowcowo-oolitowej dolnej reprezentują różnego typu płytkowodne środowiska sedymentacji (w tym środowisko równi pływowej, lagunowe i stref barierowych), jakie wykształciły się na obszarze przedgórza Karpat, na pograniczu późnej jury i wczesnej kredy. Środowisko sedymentacji utworów serii marglisto-muszlowcowej, datowanej na berias, określić można jako skrajnie płytkowodne, z facjami lagunowymi i wpływem środowisk brakicznych. Utwory najwyższych serii dolnej kredy (tj. mułowcowo-wapiennej i muszlowcowo-oolitowej górnej) reprezentują facje płytkomorskie związane z transgresją morską, która miała miejsce w walanżynie. Przedstawiona historia depozycyjna późnojurajsko-wczesnokredowego basenu sedymentacyjnego przedgórza Karpat, w połączeniu z opisem cech makroskopowych rdzeni wiertniczych, analizą mikrofacjalną i mikropaleontologiczną poszczególnych jednostek litostratygraficznych oraz interpretacją obrazu sejsmicznego, pozwala na kompleksową charakterystykę analizowanych utworów oraz wskazanie procesów mających największy wpływ na obecny charakter i stan zachowania badanych serii skalnych.
EN
The main subject of this monograph is a reconstruction of the history of deposition and facial development of Upper Jurassic and Lower Cretaceous deposits in the basement of the Carpathian Foredeep, based on data available from boreholes and a 3D seismic survey. The research area is located in the central part of the Carpathian Foreland, between two cities: Dąbrowa Tarnowska in the north-west and Dębica in the south-east. The new 3D seismic survey made in 2015 and the O-1 deep borehole – drilled in the same year and portraying a full profile of the Mesozoic sediments – allowed for much better recognition and documentation of many details of the geological structure of this previously poorly mapped area. The sedimentation of the carbonate formations of the Carpathian Foreland during the Late Jurassic and the Early Cretaceous took place in the shelf zone of the northern, passive margin of the Tethys Ocean. A characteristic feature of the Upper Jurassic sediments is their high facies diversity, due mainly to the presence of biohermal complexes and sets of layered marly-limestone sediments. Chapter 2 presents the geological structure of all structural stages in the area under study, including the lithological development, the lithostratigraphic divisions applied, and the regional palaeogeographic frameworks. Chapter 3 discusses both the history of research and the current state of knowledge regarding the Upper Jurassic and Lower Cretaceous carbonate sediments of the Carpathian Foreland. Chapter 4 describes the lithological characteristics of the carbonate sediments, considering lithostratigraphic units. This characterisation is based on a macroscopic examination of the available core material and analysis of the well logs. The lithostratigraphic profiles of selected deeper boreholes from the research area and its close vicinity document the current state of knowledge on lithostratigraphy and the facies development of the Upper Jurassic and Lower Cretaceous deposits. Chapter 5 features the microfacies and micropalaeontological characteristics of the carbonate sediments under study. Based on the results of many years of research and literature data, the possibilities of determining the age of every lithostratigraphic unit are discussed. Chapter 6 presents the analysis of the seismic 3D image based on selected seismic attributes. As part of the work, the following attributes are discussed: RMS Amplitude, Envelope, Instantaneous phase, Dominant frequency, Instantaneous bandwidth, Apparent polarity, Relative acoustic impedance, First derivative, Iso-frequency component, Time gain, Chaos, Variance (Edge method), and Local flatness. The analysis revealed additional important information regarding both the lithological development and the spatial range of sediments of individual lithostratigraphic units, at the same time facilitating the detailed location of fault zones. Based on the interpretation of the seismic image within the studied rock complex, the occurrence of angular unconformity, disturbance, and deformation zones related to synsedimentary tectonic as well as probable gravity-flow deposits are also documented. Chapter 7 presents lithofacial cross-sections constructed along selected seismic sections reflecting the spatial distribution and relationships between the sediments of individual lithostratigraphic units. Chapter 8 analyses the distribution of Upper Jurassic biohermal complexes in relation to the morphology of the Jurassic base surface. An analysis of the distribution of organic buildups belonging to the Huge Sponge-Microbial Bioherms Series, interpreted indirectly from seismic image, indicates two main areas where they can be found. These are the north-west part of the study area – where a quite extensive biohermal complex occurs (‘Complex N’), the exact range of which is difficult to determine due to later regional dolomitisation processes – and the area located in the central part of the seismic survey, where a complex of several very tall buildups with steep edges was found (‘Complex S’). Chapter 9 is devoted to the issue of the depositional history of the Late Jurassic–Early Cretaceous sedimentary basin of the Carpathian Foreland and to a discussion of the role of the most important factors influencing facies distribution in the research area. It has been shown that a characteristic feature of a large part of the Jurassic sediments is the strongly diachronic nature of the distribution of facies controlled by the varying bottom relief of the sedimentation basin and by some local factors related to synsedimentary tectonic episodes. The Sponge-Globuligerinid Series, beginning the profile of the Upper Jurassic sediments and representing the deepest sedimentation stage in the open shelf conditions, is characterised by a relatively high homogeneity of lithology in the whole Carpathian Foreland area. The ‘S’ biohermal complex developed over the elevated zone composed of several smaller tectonic elements, whilst the ‘N’ biohermal complex developed on a large, elevated part of the horst zone. The intensively developing ‘N’ and ‘S’ biohermal complexes affected successive deposition of the Late Jurassic sedimentary basin in the study area more and more. Those biohermal complexes were the source of the material redeposited into deeper parts of the sedimentary basin. On seismic profiles in the south-east neighbourhood of the ‘S’ biohermal complex, there is a characteristic high-amplitude record including the entire reflection set of variable dip angles. The frequent polarity changes which are visible within this zone in the Apparent polarity attribute, as well as the extremely variable range of values the Relative acoustic impedance attribute, prove the strong lithological differentiation of this rock complex. During the Tithonian time (sedimentation of the Coral-Oncolite Series), there was clear unification of the sedimentation conditions in the entire Carpathian Foreland area, mainly due to disappearance of the bottom relief diversity. At the same time another stage of dislocation reactivation occurred, as evidenced by the angular unconformity and the erosion traces of older sediments associated with this unconformity. The deposits of the Lower Shellbed-Oolite Series scattered throughout the research area represent various types of shallow-water sedimentation environments (including tidal, lagoon, and barrier zones) that developed in the Carpathian Foreland area on the borderline between the Late Jurassic and the Early Cretaceous. The sedimentation environment of the Marly-Shellbed Series dated to the Berriasian can be described as extremely shallow-water, with lagoon facies and under the influence of brackish environments. The sediments of the last two series of the Lower Cretaceous (i.e. the Mudstone-Limestone and Upper Shellbed-Oolite Series) represent the shallow-marine facies associated with marine transgression that took place during the Valanginian. The processes that have had the greatest impact on the current character and preservation of the rock series under study can be pinpointed and a comprehensive characterisation of these formations can be undertaken thanks to the depositional history of the Late Jurassic – Early Cretaceous sedimentary basin of the Carpathian Foreland presented herein, the macroscopic examination of the available core material, the microfacial and micropalaeontological analysis of individual lithostratigraphic units, and the interpretation of the seismic image.
EN
An Upper Jurassic succession is exposed in the active Rogaszyn Quarry (Kodrąb area) located in the Radomsko Folds structure (central Poland). Six facies types were distinguished, comprising oolitic, oncolitic, biodetrital and pelitic limestones as well as marls and marly clays. Typical lithologies are limestones with coated grains deposited in shallow-water, fore-shoal, shoal and lagoonal parts of a carbonate ramp. Three types of ooid and three types of oncoid were identified, which display several shapes and sizes, and a complex structure of cortices. The ooid types show micritic, radial-fibrous and mixed, micritic/radial-fibrous cortices. Type 1 oncoids comprise micritic or bioclastic nuclei enveloped by non-laminated or laminated micritic cortices. Type 2 oncoids are composed of micritic or bioclastic nuclei and laminated, fossil-bearing cortices covered by microbial envelopes. Type 3 oncoids are the largest of the oncoids observed, attaining cm-scale dimensions. These oncoids are formed of a Bacinella-dominated meshwork incorporating smaller ooids and oncoids, or they have bioclastic or micritic nuclei covered by complex cortices with micritic, laminated, fossil-bearing, Bacinella-dominated fabric and microbial envelopes. Boundaries between the specific types of cortical envelopes are usually sharp and accentuated by organic encrustations, elongated bioclasts or borings. Commonly found are chambers of the ichnogenus Entobia representing the boring traces of carbonate-excavating sponges and the cryptoendolithic foraminifer Troglotella incrustants. The complex cortices indicate different growth stages of oncoids at different conditions of currents and microbial activity. Carbonate deposition was accompanied by mixed siliciclastic-carbonate sedimentation resulting in multiple intercalated layers of marls and pelitic limestones as well as marly clays. The deposits exposed in the Rogaszyn Quarry as well as in the Kodrąb area are compared with the neighbouring Upper Jurassic deposits of the Szczerców area and the Sw margin of the Holy Cross Mts. (both central Poland). The successions from the Kodrąb area are generally similar to the Lower Kimmeridgian sequences known from adjacent areas, but with locally observed facies variability.
EN
Synrift basin margin successions are greatly influenced by eustatic sea level changes, tectonics and accommodation space filled in by sediments. The Middle Jurassic (Bajocian–Callovian) of Chorar Island (western India) comprises a ~109-m-thick synrift basin margin succession of clastic, non-clastic and mixed siliciclastic-carbonate rocks which are here analysed and categorised into nine lithofacies. The succession is bioturbated to varying intensities; 16 identified ichnogenera can be assigned to environmentally related groups of five trace fossil assemblages, which include Gyrochorte, Hillichnus, Rhizocorallium, Skolithos and Thalassinoides. These ichnoassemblages document the Skolithos and Cruziana Ichnofacies which marks a change in energy conditions, sedimentation dispersal patterns and bathymetry in a shallow-marine environment. The Bajocian–Callovian succession is further analysed on the basis of sedimentological and ichnological data that show two genetic sequences consisting of Transgressive Systems Tract and Highstand Systems Tract bounded by Maximum Flooding Surface. The synrift basin margin succession of the Middle Jurassic of Chorar Island shows cyclicity in deposition; the Bajocian–Bathonian succession represents progradational to retrogradational coastlines, while the Callovian succession documents an aggrading progradational coastline.
EN
In the Cambrian, the Lublin Basin was a shallow-water area, located on the western edge of the Baltica palaeocontinent. The Cambrian sedimentary sequence, forming the lower part of the sedimentary cover of the North European Platform, is lithologically diversified and reflects dynamic variation in depositional environment. This paper presents the distribution of palaeofacies and sedimentary environments in the early Lublin Basin, including changes in their lateral extent during its evolution in the Cambrian. In order to evaluate the facies architecture of the Lublin Basin, a sedimentological analysis was carried out. On the basis of the detailed logging of drill cores, lithofacies made up of conglomerates, sandstones, mudstones and heterolithic deposits were distinguished; 16 lower-rank sublithofacies were identified. Their specific assemblages are indicative of shelf-type lithofacies associations, i.e. (1) tidal flat with muddy, mixed and sandy tidal plain sublithofacies including subtidal channels; (2) barrier-lagoon; (3) shoreface with lower, middle and upper shoreface subassociations; and (4) offshore with upper and lower offshore subassociations, including sandy tidal ridges. During the early Cambrian, the lateral variability and environmental succession indicate a transgressive, long-term trend and the migration of a lagoonal environment across wide tidal plains and the shoreface up to an offshore environment. The Lublin Basin reached its greatest lateral extent and maximum depth in the upper lower Cambrian. Next, an opposite trend began and during the middle Cambrian a regression cycle is recorded in successive changes in sedimentary environments that reflect a progressive shallowing. Multiple changes in adjacent environments indicate repeated and cyclical, lower-rank ingressions.
EN
Lithofacies and ichnological features of the Coniacian deposits of the upper part of Żerkowice Member and lowest part of the overlying Czerna Formation in southeastern part of the North Sudetic Synclinorium are described and their sedimentary palaeoenvironment is interpreted. The study confirms a shallow-marine to paralic/paludine palaeoenvironment. Sedimentation of the Żerkowice Member occurred in an upper shoreface environment dominated by waves, tidal currents and wave-generated alongshore currents, with an episodic encroachment of fore shore zone and shoal-water deltas. The interpretation is supported by a high-diversity assemblage of trace fossils with 21 ichnogenera, representing a stressed expression of the Skolithos Ichnofacies dominated by Ophiomorpha nodosa and a proximal expression of the Cruziana Ichnofacies with Thalassinoides and rare specimens of diverse other ichnotaxa. Sedimentation of the Czerna Formation commenced after a stasis, with at least a local hiatus caused by emergence, and proceeded in a laterally and vertically more varied environment, with transgressive coastal lagoons evolving into freshwater lakes and marshes and with a repetitive regressive intrusion of shoreface and shoal-water deltas. The emergence of the area is recorded by coal-bearing deposits with plant-root traces. Local occurrence of the Teredolites Ichnofacies in coal (peat) deposits above the base of the Czerna Formation indicates renewed marine flooding. Continuation of the latter is locally evidenced by a trace-fossil assemblage with 17 ichnogenera, representing proximal expression of the Cruziana Ichnofacies followed by distal expression of the Skolithos Ichnofacies in the overlying transgressive-regressive cyclothems. The palaeoenvironmental changes recorded by the sedimentary succession indicate bathymetric fluctuations and imply considerable shoreline shifts and palaeogeographic changes in the basin. These changes are interpreted as a combined signal of 2nd- and 3rd-order eustatic cycles, modified and partly obliterated by the effects of intrabasinal tectonic forcing and by palaeogeographically controlled variation in sediment supply.
EN
The sedimentological and lithostratigraphic record from north-central Bir Tarfawi documents the presence of Pleistocene basin-fill deposits. Three topographic basins were created as a result of deflation during climate episodes associated with lowering of the local groundwater table. In each case, the three deflational basins or topographic depressions were subsequently filled with sediments; these basin aggradations coincided with changes from arid climate conditions to wetter conditions and a rise in the groundwater table. The oldest and highest sedimentary remnant is associated with Acheulian artifacts and may reflect spring-fed pond and marsh conditions during a Middle Pleistocene wet climate episode. Lithofacies for a lower stratigraphic sequence (the “White Lake”) documents deposition in a perennial lake that varied in extent and depth and is associated with Middle Paleolithic artifacts. A third episode of deflation created a topographic low that has been filled with Late Pleistocene sediments that are associated with Middle Paleolithic artifacts and fossil remains. Lateral and vertical variations in the lithofacies of this basin-fill sequence and the sediments of the “grey-green” lake phases provide a record of changing hydrologic conditions. These hydrologic conditions appear to reflect variations in water-table levels related to groundwater recharge and, at times, local rains.
EN
The paper presents a sedimentological analysis of Ordovician (Sandbian–Hirnantian = Caradoc–Ashgill) and Silurian (Landovery–Wenlock, lower Ludlow) claystones and mudstones from the north-eastern (Baltic Basin) and south-eastern (Podlasie-Lublin Basin) parts of the East European Craton. In both basins, formations prospective for shale gas/oil were analyzed: the Sasino Fm., Pasłęk Fm. (including the Jantar Mb.), Pelplin Fm., Udal Fm., Wrotnów Fm. and Terespol Fm. Based on lithological and sedimentological criteria, 34 lithofacies and 11 lithofacies associations have been distinguished. The most promising lithofacies arerepresentedbytheL-1,L-3andL-4associationswhicharecharacterizedbydarkgreycolour, a very low degree or lack of bioturbation, rare sedimentary structures, and common content of small pyrite concretions. They dominate in the Sasino Fm., Pas³êk Fm. (in the Jantar Mb. only) and Pelplin Fm., but are much less common in the Udal Fm., Terespol Fm. and Pas³êk Fm. (excluding the Jantar Mb.).
EN
The Krosno Formation (Oligocene) in the Silesian Tectonic Unit of the E part of the Polish Outer Carpathians is represented by two lithofacies called the Besko (or Lesko) and the Otryt facies. Their mineral composition was analysed in the past at a broad regional scale (Schideler et al. 1975) and the depositional mechanism for each facies was interpreted on the basis of sedimentary features observed on the outcrop (Ślączka & Unrug 1972, Wendorff 1987). Each of the two lithofacies forms an individual complex of strata supplied from two different source areas by turbidity currents of different hydrodynamic characteristics (Wendorff 1981, 1987). Namely, the strata of the Besko/Lesko lithofacies were interpreted as deposits of normally diluted and gradually decelerating, SE-oriented turbidity currents originating from the Silesian Ridge in the NW. On the other hand, the Otryt lithofacies is represented by deposits of rapidly decelerating high-density turbidity currents running in the opposite direction and derived from the Maramures Massif in the SE (Ślączka & Unrug 1972). The scope of this reconnaissance study is to investigate under petrographic microscope grain size, grain orientation and mineral composition of selected samples of the two sandstone types described above. These features and their comparisons should reveal whether the differences in transport and deposition mechanisms between the two lithofacies, which were in the past interpreted on the basis of macroscopic observations, are reflected by the microscopically observable features. For this purpose, and considering the reconnaissance character of this work, vertical sections of two sandstone beds were sampled in the area of the Otryt Syncline (in the Bieszczady Mts.) where these two lithofacies complexes are present. For each bed, one sample represents its lowermost part and another uppermost part. Therefore the textural characteristics of each pair of samples document hydrodynamic variations between the initiation and the final stage of deposition of the sampled bed. This is because various transport and deposition mechanisms of sediment gravity flows, and their gradients, result in differences in grain size, grain size sorting and grain orientation within a bed. The diversity of mineral composition between Besko and Otryt lithofacies is very clearly recorded in the analysed thin sections, which remains in agreement with the data published earlier and reflects different mineral composition of the respective source areas (Ślączka & Unrug 1972, Shideler et. al. 1975). The sample of the Besko lithofacies sandstone is characterised by high textural and mineralogical maturity (well-rounded grains and high quartz content). The bottom sample is moderately well sorted (standard deviation 0.64) and the top sample is moderately sorted (standard deviation 0.95). Graphic mean grain size for the bottom sample is 3.20 (Bouma Tb interval), and for the top sample 3.76 (Bouma Tc interval; both values being expressed in phi scale units). Therefore the upper sample represents deposition from a more diluted current (of lower flow competence) than the bottom sample. Less good sorting in the finer grained upper sample reflects pronounced contrasts in grain-size between individual laminae of the current-ripple cross-laminated Tc interval. Both samples of the Otryt facies sandstone show relatively high content of unstable grains, therefore this rock has low mineralogical maturity. Except for solitary well-rounded coarse grains, the bulk of grains are poorly rounded, which documents low textural maturity. The bottom sample of the Otryt facies is richer in grains of coarse to very coarse metamorphic rock fragments and polycrystalline quartz than the top-of-bed sample. Texturally, both samples are poorly sorted. This is shown by very similar standard deviation values (bottom 1.18; top 1.12). The values of graphic mean grain size range from 1.68 (bottom) to 1.92 (top). Furthermore the grain-size distribution curve of the sample from the bed bottom is characterised by coarse-tail, whereas the upper sample distribution is devoid of coarse-tail. These values and their distributions imply grain-size sorting by a high-density turbidity current unable to separate the various grain-size classes present in the flow. In such flows only the coarsest fraction is present initially but the remaining spectrum of the grains remains unchanged throughout the depositional process (Shideler et. al. 1975). A comparison between the two sets of samples shows the influence of two different flow types expressed by notable differences in grain size and sorting. The Besko facies sandstone is finer grained due to having been deposited from a more diluted current of lower competence. Furthermore, the Besko facies sandstone must have been deposited from a gradually decelerating current whereas the Otryt facies sandstone was deposited rapidly by denser turbidity current in which grain-size sorting affected only the coarsest grains. As a consequence grain orientation parallel to the flow direction is more distinct in the Besko facies than in the Otryt facies sandstones.
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The Hoanh Bo Basin is a multiple period formed basin which is associated with the tectonic mechanism due to the activity of the Chi Linh-Hon Gai and Trung Luong Faults during the late Paleogene – early Neogene time. The basin is filled with continental sediments, comprising mainly polymictic conglomerates, sandstones, siltstones, claystones and shales. Coarser-grained polymictic deposits predominate along the northern and western margins of the basin, while different types of siltstones, claystones, even sandstones occur in its center, as well as along its southern and eastern parts toward the Ha Long Bay. The source rocks for sedimentary materials are mainly originated from rocks of the Hon Gai and Ha Coi Formations. Based on the dominant grain-size class, texture, stratification, degree of clast rounding and sorting, 17 lithofacies were determined in the Hoanh Bo Basin infill. The basin is filled by gravelly, sandy and fine-grained lithofacies just covers a modest area but it represents a full of succession of 4 depositional systems including alluvial fan, fluvial, deltaic and lacustrine environments. Alluvial fan and fluvial environments are characterized by an assemblage of lithofacies such as sand- and mud-supported disorganized breccias (Gb), clast- to sand-supported conglomerates (Gmm), clast-supported inverse-graded conglomerates (Gig), planar-cross-bedded conglomerates (Gp), trough cross-bedded conglomerates (Gt), horizontally stratified conglomerates (Gh), planar cross-bedded sandstones (Sp), trough cross-bedded sandstones (St), ripple cross-laminated sandstones (Sr), horizontally bedded sandstones (Sh), massive sandstones (Sm), massive mudstones, siltstones (Fsm), laminated siltstones and mudstones (Fl), massive claystones (Fm) and coaly lithofacies (C); the deltaic assemblage is dominated by planar-cross-bedded conglomerates (Gp), horizontally stratified conglomerates (Gh), planar cross-bedded sandstones (Sp), horizontally bedded sandstones (Sh), low-angle cross-bedded sandstones (Sl); while the lacustrine assemblage consists of ripple cross-laminated sandstones (Sr), horizontally bedded sandstones (Sh), normally graded sandstones (Sng), massive mudstones, siltstones (Fsm), laminated siltstones and mudstones (Fl), massive claystones (Fm) and coaly lithofacies (C).
EN
The identification of depositional conditions and stratigraphical position of glacigenic deposits in the Napęków area is important for the genetic and stratigraphical interpretation of Quaternary deposits in the central part of the Holy Cross Mountains, as well as for a revision of the course and extent of Middle Polish (Saalian) glaciations. These deposits comprise a series of diamictons which occur between sandy-gravelly deposits. Based on results of macro- and microscopic sedimentological investigations, analysis of heavy mineral composition, roundness and frosting of quartz grains, as well as OSL dating, this complex must have formed during the Odranian Glaciation (Drenthe, Saalian, MIS 6). Sandy-gravelly deposits are of fluvioglacial and melt-out origin. Diamictons represent subglacial traction till. Their facies diversity is a result of variations in time and space, complex processes of deposition and deformation, responsible for their formation at the base of the active ice sheet. This glacigenic depositional complex was transformed by erosion-denudation and aeolian processes in a periglacial environment during the Vistulian (Weichselian, MIS 5d-2).
EN
Silurian strata, stretching along the western margin of the East European Platform from the Baltic to the Black Sea, represent a potential target for both conventional and unconventional hydrocarbon exploration. Distribution of the black shale facies, prospective for shale gas, and the reef facies, prospective for oil, has been studied in respect of palaeoenvironments. The Silurian sequence has been investigated in the territory of Ukraine (Volyn-Podillyan Plate, Dobrogean Foredeep) and correlated with the data on Moldova and Romania (Moldovian Platform). The occurrence of Silurian strata, their thickness, and petrographic and lithological characteristics allowed reconstructing the distribution of open-shelf, reef and lagoonal facies. The reef facies migrated during the Wenlock–Middle Pridoli, shifting towards the open sea and back towards the shore, and therefore has been termed a migrating reef facies. Correspondingly, the boundary between the open-shelf and reef facies was shifting. The facies distribution was controlled by the transgressive-regressive cycles, which caused the fluctuations of the shelf water depth in different time intervals of the Silurian. The shelf water depth of about 100 m, where the top of the oxygen-minimum layer impinged on the sea bottom, was the boundary between the open-shelf facies, represented by organic-rich sediments, and the reef buildups.
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The Orava-Nowy Targ Basin is an intramontane depression located at the border of the Inner and Outer Carpathians. It is filled mostly with fine-grained terrestrial and fresh-water deposits of Neogene and Quaternary age, which record the structural evolution and denudation processes of the surrounding regions: Orava, Podhale, and the Tatra Mts. The Orava-Nowy Targ Basin fill was studied in the Oravica River section, which reveals 90 m thick Neogene deposits and allows observation of their lateral diversity. Fifteen lithofacies and seven facies associations distinguished here document the depositional evolution of the basin fill, starting from hill-slope debris flow through silt turbidite-bearing lake, to flood-dominated fluvial plain, swamp and alluvial fan deposits, as well as a pyroclastic event. The palaeorelief was low during deposition and the Orava-Nowy Targ Basin could have spread significantly more to the south.
EN
Ground-penetrating radar (GPR) surveys and sedimentological outcrop analyses were combined in order to determine the reflection patterns and internal architecture of terrace deposits of the Vistula River at Kępa Zawadowska in the southern part of Warsaw (central Poland). The sedimentary analyses concerned the granulometric composition and lithofacies analysis. The 34 GPR profiles, which were obtained in two outcrops, using a Malå RAMAC/GPR system with 500-MHz and 250-MHz shielded antennas, were up to 100 m long. The most characteristic ground-penetrating radar profiles are presented; they show a high-resolution data set of radar facies. The GPR data suggest the presence of three geophysically different units, namely with high-angle inclined reflections (radar facies 1), with discontinuous undulating or trough-shaped reflections (radar facies 2), and with low-angle reflections (radar facies 3). The internal structure of the fluvial deposits was obtained by integration of the GPR and sedimentological data, which combination provides a more accurate visualisation of sedimentary units than do reconstructions that are based only on standard lithologic point data.
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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.
EN
Turbidite sandstones deposited in rift settings are currently among the main targets of hydrocarbon exploration. However, the impact of style of sedimentation, cyclicity and diagenesis on reservoir quality of such sandstones is relatively poorly explored in the literature. The sedimentology, stratigraphic architecture, and diagenetic alterations of deep marine sandstones of the Mocene Nutaysh member of the Burqan Formation in the Midyan area (Saudi Arabia) are described based on number of measured sedimentologic sections, lithofacies identification in the field and laboratory studies. Three lithofacies types are here identified in the measured sections. These are from bottom to top: (1) “Lithofacies A” consisting of massive to thickly-bedded, coarse-to-very coarse-grained sandstone and conglomerates; (2) “Lithofacies B” consisting of well-bedded, coarse-to-medium-grained, well-sorted sandstone, and (3) “Lithofacies C” consisting of thin-bedded, fine to very fine-grained, current-rippled sandstone, bioturbated shaley siltstone and marl. The main diagenetic processes in the sandstones include the formation of grain-coating smectite and rhombic dolomite. Small amounts of cements include the formation of authigenic kaolinite and calcite. The reservoir quality is anticipated to have been preserved under the transformation of smectite to deep burial illite, which is believed to prevent formation of quartz cements.
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