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EN
This paper deals with the lithostratigraphic correlation of the Ordovician-Silurian succession between the Baltic, Podlasie and Lublin basins, located on the SW slope of the East European Craton. The correlation is based on previous lithostratigraphic classifications, which are modified here to include the results of recent biostratigraphic and sedimentological work performed on several new wells. The authors propose to extend the Sasino Formation for the entire upper Darriwilian-lower Katian mudstone sheet that is traceable in all basins. It is recommended that the Jantar Bituminous Claystone Member (late Hirnantian-Aeronian) of the Pasłęk Formation be elevated to the rank of formation and the name Pasłęk Mudstone Formation be retained for the late Aeronian-Telychian, rhythmic alternations of black, laminated mudstones and greenish, bioturbated mudstones. Moreover, the authors suggest that the top of the Kociewie Formation (Sheinwoodian-Ludfordian) be placed at the upper boundary of the Reda Member (latest Ludfordian), which shows much wider lateral persistence than previously was thought.
EN
This paper deals with the graptolite biostratigraphy and age determination of the Ordovician and Silurian lithological successions of the Baltic, Podlasie and Lublin basins that existed during the early Palaeozoic on the SW slope of the East European Craton. The biostratigraphic research described was conducted on core material coming from old boreholes and cores from several new wells. Graptolite zones were identified and the chronostratigraphic succession was constrained, with the depths to the stratigraphic units, especially those considered prospective for petroleum, being determined in the individual borehole sections. Old local stratigraphic schemes of the Silurian used for many years in the Polish geological literature are correlated with the standard schemes. The most complete succession of graptolite zones, both in the Ordovician and the Silurian, is observed in the Baltic region. The number of stratigraphic gaps increases towards the east and southeast of the regions. The stratigraphic range of the Sasino Shale Formation decreases in this direction; in the Podlasie and Lublin regions, it comprises only the Katian Stage. The stratigraphic range of the Jantar Formation in the western part of the area spans not only the Rhuddanian but also part or the whole of the Aeronian. In the Podlasie and especially the Lublin regions, sedimentation of the Jantar Formation began in the latest Rhuddanian–Aeronian. A large stratigraphic gap, spanning part or the whole of the Llandovery and increasing eastwards, was documented in the Podlasie-Lublin region. The biostratigraphic research allowed a more precise constraint on the temporal and spatial extent of erosion of Pridoli deposits and the beginning of coarse-grained, siliciclastic sedimentation (Kociewie Formation) in the Baltic Basin.
3
Content available remote Ordovician seawater composition : evidence from fluid inclusions in halite
EN
Fluid inclusions in halite can directly record the major composition of evaporated seawater; however, Ordovician halite is very rare. The Ordovician is a key time during the evolution history because profound changes occurred in the planet’s ecosystems. Marine life was characterized by a major diversification, the Great Ordovician Biodiversification Event and the Late Ordovician Mass Extinction, the first of the “big five” mass extinctions. However, so far there is no data on the Ordovician seawater. Data from the Ordovician-Silurian boundary were available only. In this study, we report the major compositions from Middle Ordovician halite in China to give the exact composition of Ordovician seawater. The basic ion composition (K+, Mg2+, Ca2+, and SO42-) of inclusion brines was established with the use of ultramicrochemical analysis. The data on the chemical composition of the brines in the primary inclusions indicated that the brines were of Na-K-Mg-Ca-Cl (Ca-rich) type, and cover a huge gap in the evolution of seawater chemistry. The chemical composition of the primary inclusion brine in halite confirmed the earlier results for the Cambrian and Silurian halite originating from other salt basins and the previous speculation of “calcite sea” during the Ordovician, indicating a higher potassium content in the Lower Paleozoic seawater than in the seawater of other periods of the Phanerozoic.
EN
The Middle Ordovician Bukówka Formation, composed of fine-grained quartz sandstones with siltstone intercalations, belongs to the Kielce Region of the Holy Cross Mountains (peri-Baltic palaeogeographic position). It contains trace fossils of low diversity and poor preservation. Particularly noteworthy are the large Cruziana and Rusophycus, that are typical of peri-Gondwanan areas. They consist of casts of bilobate furrows showing diverse preservation. Other trace fossils include mostly horizontal pascichnia, cubichnia, and fodinichnia, but also vertical domichnia. The trace fossil assemblage is typical of the archetypal Cruziana and partly of the Skolithos ichnofacies. Some beds contain abundant orthid brachiopods. The trace fossils and sedimentary structures (horizontal, low-angle and wave ripple cross-laminations, hummocky cross-stratification) suggest deposition on the middle and lower shoreface with storm influence. The poor preservation and low diversity of the trace fossils are related to the homogeneous lithology, low accumulation rate, shallow burial of organic matter and strong bioturbation. Therefore, animals burrowed strongly but mostly in shallow tiers. Thus, the preservation potential of their traces was much lower than in many peri-Gondwanan sections but still higher than in Baltica sedimentary rocks. This explains the provincial differences in ichnofauna during the Ordovician, which at least partly were influenced by the preservation potential.
EN
This is the first report of encrusted cryptic surfaces in the Ordovician of Estonia. Only bryozoans and cornulitids occurred in nautiloids and trilobites. Bryozoans were the dominant encrusters, in terms of both the number of specimens and the encrustation area. Stalked echinoderms are common on the hardgrounds in the Middle and Upper Ordovician of Baltica, but the restricted space in nautiloid living chambers and trilobites probably prevented colonization by stalked echinoderms. Cryptic surfaces in nautiloids and trilobites usually are somewhat more encrusted than the open surfaces of hardgrounds in the Ordovician of Estonia. Encrusters presumably favoured cryptic surfaces, as these were less accessible for predators and grazers. Low encrustation densities, compared to North American hard substrates, seem to be characteristic for the Ordovician Baltic Basin.
6
Content available remote Nowe stanowisko unikatowej fauny z dolnego ordowiku Chin
EN
Majority of the palaeontological data are collectedfrom skeletonized specimens. As a result, our perception of biodiversity in the geological past is very incomplete since most organisms did not have a mineralized skeleton, and therefore had no chance to be preserved in rock. Butfortunately, there are also sporadic unusualfindings (known as taphonomic windows or Konservat-Lagerstätten) with exceptional preservation of fossils material, sometimes with preserved soft tissues. Such exceptional fauna was recently discovered in the Lower Ordovician Fenxiang Formation in Xingshan county of Hubei province in China. This important fauna is represented by linguloid brachiopods with remarkably preserved pedicle, the oldest traces of nematode life activities, the oldest reliable record of hydroids, the first fossil antipatharian corals, an enigmatic clonal organism probably of pterobranch affinity and conulariid Sphenothallus revealing serially arranged sets of septa-like structures. Our discovery support claim thatfamous Cambrian soft-bodiedfaunas of Burgess- or Chengjian-type did not vanish from thefossil record in post-Cambrian strata.
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 hill range of Vaivara Sinimäed in northeast Estonia consists of several narrow east- to northeast-trending glaciotectonic fold structures. The folds include tilted (dips 4-75°) Middle Ordovician (early Darriwilian) layered carbonate strata that were studied by mineralogical, palaeomagnetic, and rock magnetic methods in order to specify the postsedimentational history of the area and to obtain a better control over the palaeogeographic position of Baltica during the Ordovician. Mineralogical studies revealed that (titano)magnetite, hematite, and goethite are carriers of magnetization. Based on data from 5 sites that positively passed a DC tilt test, a south-easterly downward directed component A (Dref = 154.6°± 15.3°, Iref = 60.9°± 9.7°) was identified. The component is carried by (titano)magnetite, dates to the Middle Ordovician (Plat = 17.9°, Plon = 47.3°, K = 46.7, A95 = 11.3°), and places Baltica at mid-southerly latitudes. Observations suggest that in sites that do not pass the tilt test, the glaciotectonic event has caused some rotation of blocks around their vertical axis.
PL
Wykonano próby obliczania parametrów sprężystych dla łupków ilastych, będących potencjalnymi skałami macierzystymi dla węglowodorów. Wykorzystano w tym celu znane modele teoretyczne Biota–Gassmana i Kustera–Toksöza oraz autorski program Estymacja-TP. Przeprowadzono wstępną analizę wartości parametrów szkieletowych niezbędnych do obliczeń. Analiza została oparta na danych literaturowych oraz na pracach autorki. Zmiany parametrów sprężystych skał macierzystych, jak również ich wzajemne relacje dostarczają ważnych informacji o wielkościach generowanych węglowodorów i charakterystykach geomechanicznych skał, określanych na podstawie profilowań akustycznych i pomiarów sejsmicznych. Modele syntetyczne skał ilastych zawierają uśrednione wielkości charakterystyczne dla łupków gazonośnych Barnett Shale w Teksasie, łupków Green River w Colorado oraz łupków syluru i ordowiku z basenu bałtyckiego.
EN
Tests were carried out for calculating the elastic parameters for shales, which are potential hydrocarbons source rocks. For this purpose the Biot–Gassmann and Kuster–Tosköz theoretical models and original program ESTYMACJA TP were used. A preliminary analysis of the values of the matrix of the rocks were made, which are necessary for the calculations. The analysis were based on literature data and recent works by the author. Changes in elastic parameters of source rock and their relationships provide important information about the volumes of the generated hydrocarbons and geotechnical characteristics of rocks, determined on the basis of acoustic logs and seismic measurements. The developed synthetic shale rock models contain averaged values characteristic for the organic-rich Barnett Shale in Texas, Green River shale in Colorado and Silurian, and Ordovician shales of the Baltic Basin.
EN
In connection with the exploration of zones prospective for the occurrence of unconventional hydrocarbon deposits, numerous studies of source rocks have been conducted in Poland. Stratigraphic examinations are among the basic elements. The main group of fossils occurring in shale successions, being a potential source of hydrocarbons, is graptolites. This paper describes the assemblages of graptolites from Ordovician and Silurian deposits and shows their importance for the stratigraphy of shale complexes. Due to their abundance and rapid evolution, graptolites are an excellent tool for biostratigraphic dating, regional correlations and biozonation of rock successions in terms of the high-resolution sequence stratigraphy. The paper presents the significance of taphonomic research of graptolites to identify zones of increased accumulation of hydrocarbons in rocks. It has been found that graptolites are an equally important instrument, in addition to elevated TOC values or increased gamma ray radiation on well logs, that allows identification of potential source rocks for hydrocarbons, including shale gas.
EN
In connection with the exploration of zones prospective for the occurrence of unconventional hydrocarbon deposits, numerous studies of source rocks have been conducted in Poland. Stratigraphic examinations are among the basic elements. The main group of fossils occurring in shale successions, being a potential source of hydrocarbons, is graptolites. This paper describes the assemblages of graptolites from Ordovician and Silurian deposits and shows their importance for the stratigraphy of shale complexes. Due to their abundance and rapid evolution, graptolites are an excellent tool for biostratigraphic dating, regional correlations and biozonation of rock successions in terms of the high-resolution sequence stratigraphy. The paper presents the significance of taphonomic research of graptolites to identify zones of increased accumulation of hydrocarbons in rocks. It has been found that graptolites are an equally important instrument, in addition to elevated TOC values or increased gamma ray radiation on well logs, that allows identification of potential source rocks for hydrocarbons, including shale gas.
EN
Quantity, genetic type and maturity of organic matter dispersed in the Lower Palaeozoic sequence from the Lower Cambrian to Silurian strata of the Polish and Ukrainian parts of the Carpathian Foredeep basement in the Tarnogród–Stryi area were evaluated based on the results of geochemical analyses of 475 rock samples collected from 45 wells. The best source rocks were found in the Silurian strata where the present total organic carbon (TOC) content is up to 2.6 wt%. They occur in the vicinity of Wola Obszańska, where the median of the present and the initial total organic carbon (TOC) contents in the individual wells amount to 0.98 and 1.6 wt%, respectively. The Cambrian and Ordovician strata have a poorer hydrocarbon potential and their present TOC content never exceeds 1 wt%. In all of the investigated Lower Palaeozoic strata, organic matter is represented by the oil-prone Type-II kerogen deposited in anoxic or sub-oxic conditions. The maturity of source rocks ranges from early mature (the initial phase of the low-temperature thermogenic processes) in selected zones of the Silurian strata in the vicinity of Wola Obszańska, through the middle and the final phase of “oil window” in the Ordovician and Cambrian strata in the Polish part of the study area, to the overmature stage in the Ordovician strata in the south-eastern part of the study area (Ukraine).
EN
New biostratigraphic and lithostratigraphic data are presented for the tectonically reduced Ordovician succession at Pobroszyn in the Łysogóry region of the Holy Cross Mountains, central Poland. Only some of the chronostratigraphic units known from the Łysogóry region can be recognized in this section. However, based on lingulate brachiopods, conodonts, acritarchs and chitinozoa, the units present may be referred to the Late Tremadoc, Late Arenig, Early Lanvirn, Late Lanvirn, Early Caradoc and to the Middle Caradoc and Ashgill. New lithostratigraphic units are established in the lower part of the Ordovician of the Pobroszyn section: the Opatówka Mudstone/Sandstone Formation (?Late Tremadoc) and the Pobroszyn Sandstone Formation (Late Arenig). Three species of lingulate brachiopods are described, of which two are new: Myotreta anitae and Eoconulus lilianae. The conodonts and acritarchs are illustrated and briefly discussed.
EN
Determining kinetic parameters for oil generation from a source rock by hydrous pyrolysis requires a considerable amount of sample (kilograms) and laboratory time (several weeks). In an effort to circumvent these requirements, hydrous-pyrolysis (HP) kinetic parameters for oil generation from Upper Cambrian and Tremadocian source rocks of the Baltic region are estimated by two methods: (1) organic sulfur content in kerogen and (2) HP experiments conducted at 330 and 355°C for 72 h. Estimates for the Upper Cambrian source rocks based on organic sulfur contents gave activation energies from 47 to 56 kcal/mole and frequency factors from 1.156 ' 1025>/sup> to 1.078 ' 1028 m.y.-1 . Tremadocian source rocks based on organic sulfur content gave estimated activation energies from 60 to 62 kcal/mole and frequency factors from 1.790 ' 1029 to 1.104 ' 1030 m.y.-1 . The estimates for the Tremadocian source rocks were less affected by thermal maturation because their low kerogen S/(S + C) mole fractions (< 0.018) remained essentially constant. Conversely, the higher kerogen S/(S + C) mole fractions (>>gt; 0.018) of the Upper Cambrian source rocks decreased with thermal maturation and resulted in overestimation of the kinetic parameters. The second method was designed to estimate kinetic parameters based on two HP experiments. The assumption that the maximum yield in calculating the rate constant at 330°C (k330°C could be determined by a second hydrous pyrolysis experiment at 355°C for 72 h proved not to be valid. Instead, a previously established relationship between Rock-Eval hydrogen index and maximum HP yield for Type-II kerogen was used to calculate k330°C from oil yields generated by the HP experiment at 330°C for 72 h assuming a first-order reaction. HP kinetic parameters were determined from relationships between k330°C and the HP kinetic parameters previously reported. These estimated HP kinetic parameters were in agreement with those obtained by the first method for immature samples, but underestimated the kinetic parameters for samples at higher thermal maturities. Applying these estimated HP kinetic parameters to geological heating rates of 1 and 10°C/m.y. indicated that the Upper Cambrian source rocks would generate oil notably earlier than the overlying Tremadocian source rocks. This was confirmed in part by available data from two neighboring boreholes in the Polish sector of the Baltic.
EN
In Ordovician times the Łysogóry Region (northern Holy Cross Mts.) was located in the marginal part of Baltica, thus, the sea-level history reconstructed for this palaeocontinent appears to be a good background for discussing relationships between sea-level changes and the studied sedimentary record. However, some stratigraphic gaps, e.g. in the Lower and Middle Ordovician parts of the considered succession are probably due to regional tectonic activity. The upper Middle and Upper Ordovician sedimentary facies of the Łysogóry Region show good correlation with the Late Llanvirn-Caradoc Highstand Interval followed by the Ashgill Lowstand Interval in Baltica (Nielsen, 2004). The most conspicuous facies changes in the Ordovician of the considered region seem to be coeval with 3rd order eustatic events recognized on the sea-level curve from Baltoscandia.
EN
The paper presents the detailed plate tectonic, paleogeographic, paleoenvironment and plaeolithofacies maps for eight Early Paleozoic time intervals. Forty maps, generated using PLATES and PALEOMAP programs, contain information about plate tectonics, paleoenvironment, and plaeolithofacies during Cambrian, Ordovician and Silurian. Disintegration of supercontinent Pannotia and origin of Gondwana, Laurentia and Baltica occur during Early Cambrian. Oceans spreading continued during Late Cambrian and Early Ordovician; vast platform flooded by shallow seas existed on the continents. The plate tectonic reorganization happened during Middle Ordovician. Silurian was a time of Caledonian orogeny, closing of Early Paleozoic oceans and origin of supercontinent Laurussia as a result of Laurentia and Baltica collision. Information contained within global and regional papers were posted on the maps and the detailed paleoenvironment and plaeolithofacies zones were distinguished within the platforms, basins and ridges.
PL
Artykuł przedstawia szczegółowe mapy paleogeograficzne dla ośmiu przedziałów czasowych w obrębie wczesnego paleozoiku. Czterdzieści map, skonstruowanych przy użyciu programów PLATES i PALEOMAP, zawiera informacje dotyczące tektoniki płyt, paleośrodowiska i paleolitofacji w czasie kambru, ordowiku i syluru. We wczesnym kambrze nastąpił rozpad superkontynentu Pannotia i utworzyły się kontynenty: Gondwana, Laurencja, Bałtyka i Syberia. W późnym kambrze i wczesnym ordowiku w dalszym ciągu ma miejsce spreding oceanów, istnieją też w tym czasie rozległe platformy zalane przez płytkie morza na kontynentach. Reorganizacja płyt litosfery nastąpiła w środkowym ordowiku. Sylur był okresem orogenezy kaledońskiej, zamknięciem wczesno- paleozoicznych oceanów i powstania superkontynentu Laurosji z połączenia Laurencji i Bałtyki. Informacje zawarte w szeregu globalnych i regionalnych prac zostały naniesione na mapy, a w obrębie platform, basenów i grzbietów wydzielono poszczególne strefy paleośrodowiskowe i paleolitofacjalne
EN
The Middle Ordovician (Dapingian) of the northern Holy Cross Mountains (central Poland) is represented by condensed limestones that make up the Pobroszyn Formation. They reveal a complex stratification reflecting alternating depositional conditions. The basal limestones were deposited in open-marine conditions during the early Middle Ordovician sea level rise (navis Zone) correlated with the Baltoscandian Gärdlosa drowning. Periods of non-deposition associated with this transgression favoured precipitation of authigenic Fe minerals close to the sediment-water interface. The upper part of this succession appears to representa succeeding depositional phase associated with a second transgressive event, which probably involved reworking of the underlying lithified substrate. High energy events were interrupted by periods of non-deposition favouring development of benthic microbial communities contributing to Fe authigenesis. The Pobroszyn Formation reveals features suggesting an early diagenetic alteration of the parent carbonate sediment in a shallow ma rine setting (e.g., beach shoreface) or even was influenced by meteoric diagenesis, which probably took place during a sea level fall preceding the second transgressive event.
PL
W artykule zaprezentowano sformalizowany schemat podziału litostratygraficznego osadów klastyczno-węglanowych ordowiku polskiego fragmentu obniżenia podlaskiego (wschodnia Polska) oraz podłoża niecki płocko-warszawskiej. W sekwencji litologicznej systemu wyróżniono, opierając się na makroskopowej zmienności cech sedymentacyjnych i sedymentacyjno-diastroficznych osadów, 18 formalnych jednostek litostratygraficznych, w tym: 15 o randze formacji oraz 3 w randze ogniwa. Z proponowanych formacji 11 wyróżniono w obniżeniu podlaskim, pozostałe 4 w podłożu niecki płocko-warszawskiej. Część ustanowionych jednostek jest ograniczona regionalnymi powierzchniami nieciągłości sedymentacyjnych lub sedymentacyjno-erozyjnych i spełnia kryteria właściwe kategoriom Iitostratygraficznym o charakterze allostratygraficznym (allostratigraphic units). Przedstawiono zasięg stratygraficzny, zgeneralizowaną litologię, miąższość i charakter granic poszczególnych jednostek litostratygraficznych, ich następstwo pionowe i wzajemne relacje przestrzenne. Zespoły skalne poszczególnych formacji skorelowano z ich litostratygraficznymi i genetycznymi odpowiednikami w profilach obszarów sąsiednich: Polski, Białorusi, Ukrainy, Litwy i Rosji (Obwód Kaliningradzki).
EN
Investigations of Ordovician rocks of the Podlasie Depression and Płock-Warsaw Trough (eastern Poland) have resulted in establishing and defining of 18 new formal Iithostratigraphical units, including 15 formations and 3 members. Out of the units of formation rank four units have been established within the basement of the Płock-Warsaw Trough, and 11 units in the Podlasie Depression. Some of them show features of allostratigraphic units sensu "North American..." (1983) because they are bordered by sedimentary or sedimentary-erosional unconformities. The units have been defined in accordance with the rules of the Polish stratigraphic nomenclature. The description includes as follows: name, history, subdivision, type section, other sections, boundaries, lithology, organic remains and age, sedimentary environment, thickness and age equivalents. The lithology, stratigraphical position, thickness, palaeontological data and spatial relation of the particular units are presented in this paper. Rock sequences of different formations have been correlated with lithostratigraphic and genetic equivalents from the adjacent regions of Poland, Belarus, Ukraine, Lithuania and Russia (Kaliningrad District).
20
Content available remote Litostratygrafia ordowiku w Górach Świętokrzyskich
EN
The study of the Ordovician conducted in the Holy Cross Mts. during the last two decades provided new data concerning lithology and stratigraphy of this system. Thus, the revised Ordovician lithostratigaphy of the Holy Cross Mts., presenting a complex temporal stratigraphic and lithofacies pattern is needed. The lithostratigraphic proposal, presented in this paper, includes seventeen formations defined in accordance with formal requirements. They are characterized by macroscopically identified sets of lithologic features, which differentiate one unit from another.
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