Wyniki wyszukiwania - Biblioteka Nauki

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Foramineral biozonation of the early and middle jurasic in the Pieniny klippen belt (Carpathians)

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Tyszka J.

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tom Vol. 47, nr 1

27-46

EN

A new biozonation scheme here proposed is based on benthic foraminifers recovered from the Toarcian to Bajocian deposits in the Pieniny Klippen Belt, Carpathians (Poland and Slovakia). Four zones and two subzones are established and correlated to ammonite biostratigraphy. The marker species included here are those consideres to be the most important for local and regional (Franke), Lenticilinad'orbignyi (Roemer), and L.quenstendti (Gümbel) are valuable for global correlation purposes.

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Paleoclimatic analysis of Quaternary sediments associated with the floodplain deposits of a tropical estuary along the southwestern cost of India

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Murali D. , Reghunath R. , Prakash P. , Bhushan R. , Krishnan K. A. , Baby S. R.

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tom Vol. 41, Nr 1

13--21

EN

The coastal regions of southwest India which falls in the tropical regime, have witnessed many transgression-regression events and climatic extremes in the Quaternary Period. A core, 15 m long, was recovered from the floodplains associated with a typical backwater body (lake) in the southwestern coast of India. The granulometric analysis proved dominance of sand and silt fractions and extremely high energy conditions over the entire core. The TOC/TN ratio indicated a domination of the C4-type over the C3-type plants in the lower half of the core, suggesting a warm climate. The C3-type plants prevail in the upper part of the core, thus reflecting cool and wet environments. Extremely low values of TOC/TN ratio (0.33% to 10%) of the core indicate short periods of very high rainfall events and the rapid influx of nutrients to the basin and the eutrophication of the basin. The presence of slightly brackish, brackish/marine and marine benthic foraminifers at 12.5–9 m depth indicates episodes of transgression and regression. The derived AMS radiocarbon dates suggest the Marine Isotope Stage 3 for the lower part of the core.

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Impact of shelf-transformed waters (STW) on foraminiferal assemblages in the outwash and glacial fjords of Adventfjorden and Hornsund, Svalbard

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Szymańska N. , Pawłowska J. , Kucharska M. , Kujawa A. , Łącka M. , Zajączkowski M.

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tom No. 59 (4)

525--540

EN

A new dataset of benthic foraminiferal assemblages from Adventfjorden (tributary fjord of Isfjorden, West Spitsbergen) was compared with the results of a study conducted by Zajączkowski et al. (2010) in Hornsund (West Spitsbergen). According to Nilsen et al. (2016), Atlantic water inflow to the Isfjorden Trough occurs more readily than to anywhere else along the shelf of Spitsbergen; thus, we compared the foraminiferal assemblages of the outwash Adventfjorden fjord, located in the Isfjorden system, with glacial Hornsund, located in southwest Spitsbergen. Despite the juxtaposition of Adventfjorden and Hornsund the data revealed varying impacts of shelf-transformed water (STW) on the benthic foraminiferal assemblages. Outer and central Adventfjorden was dominated by Adercotryma glomerata, Recurvoides turbinata and Spiroplectammina sp., reflecting the presence of STW, while abundant Melonis barleeanus in the central area of the fjord indicated a large flux of unaltered organic matter. Only the head of the fjord was dominated by the glaciomarine taxa Cassidulina reniforme and Elphidium clavatum. Foraminiferal fauna characteristic of STW-influenced environments (i.e., Nonionellina labradorica and R. turbinata) were also observed in outer Hornsund. However, the glacier-proximal taxa E. clavatum and C. reniforme were dominant throughout the fjord, demonstrating the impacts of meltwater and high sedimentation. Therefore, it is likely that in Hornsund, glacial impact is a major environmental factor, which is stronger than the influence of STW.

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Cretaceous (Aptian/Albian-?Cenomanian) age of “black flysch” and adjacent deposits of the Grajcarek thrust-sheets in the Male Pieniny Mts. (Pieniny Klippen Belt, Polish Outer Carpathians)

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Oszczypko N. , Olszewska B. , Malata E.

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2012

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tom Vol. 56, No 3

411--440

EN

Several sections record the relation between the “black flysch” and Upper Cretaceous red shales in the Grajcarek thrust-sheets. In all the sections studied the “black flysch” appears in the core of imbricated folds or thrust-sheets, whereas the limbs are composed of Upper Cretaceous deposits. The transitional beds between the “ black flysch” and the Upper Cretaceous red shales are composed of green and black bituminous shales, green and red radiolarites and cherty limestones. Biostratigraphical investigations have revealed a similar type and sequence of microfauna assemblages in all the sections studied and significant redeposition of Jurassic calcareous benthic foraminifera, calcareous nannoplankton, molluscs, sponge spicules and crinoid elements. The Cretaceous age (Aptian/Albian-?Cenomanian) of the “black flysch” is shown by the presence of agglutinated foraminifera and microfacies data. These deposits are underlain by a Kimmeridgian-Aptian radiolarite/limestone condensed succession and overlain by Turonian-Campanian hemipelagic red shales and Maastrichtian/Lower Paleocene conglomerates and thick-bedded silicilastic turbidites of the Jarmuta Formation. Such a sequence of deposits is typical of the Outer Carpathian basins and records the global Mid/Late Cretaceous phenomena in the world ocean, followed by the Cretaceous Oceanic Red Beds.

5

Middle Devonian Foraminifera from the Holy Cross Mountains

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Gajewska M.

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tom Vol. 92, No. 4

411--424

EN

The Middle Devonian was an exceptional time for foraminiferal evolution because of the emergence of the first true calcareous multilocular taxa. Despite being key forms for an understanding of the origin of foraminiferal multilocularity, which is one of the most intriguing events in the evolutionary history of the group, they are largely unstudied. These unique foraminifera, including representatives of the genera Cremsia, Moravammina, Pseudopalmula, Semitextularia, and Vasicekia, are presented herein as well as foraminifer-like microfossils of uncertain biological position. The studied material comes from the Middle Givetian strata of the Miłoszów section and the Eifelian part of the Grzegorzowice-Skały section (Holy Cross Mountains, Poland). Described isolated specimens are in an exceptionally good state of preservation on a worldwide scale, which enabled the detailed analysis of test morphologies, complementing previous papers based on less well-preserved material. The suggested systematics of the foraminifera collected attempts to revise scarce taxonomic data that is still under debate, especially the classification of Moravammina, Cremsia, and Vasicekia. The Devonian foraminifers presented were prominent endobenthic and epibenthic inhabitants of common organic coral-stromatoporoid buildups. Palaeobiogeographical records show that during the Middle Devonian, the studied forms extended their exclusive European distribution into further Laurussian shelves and shallow seas, located in the northern and southeastern parts of the Rheic basin. This assumes that such assemblages may be used as palaeoenvironmental indicators. However, at present, their correlative potential is unknown.

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Palaeoenvironmental changes in the Transylvanian Basin during the Early Miocene revealed by the foraminifera assemblages

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Székely S. F. , Beldean C. , Bindiu R. , Filipescu S. , Săsăran E.

Geological Quarterly

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2016

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tom Vol. 60, No. 1

167--180

EN

The evolution of the Transylvanian Basin during the Early Miocene has been restored from the succession of palaeoenvironments inferred from the sedimentological trend and succession of specific foraminifera assemblages from Lower Miocene Tihău section in northwestern Transylvanian Basin. Planktonic foraminifera suggest a Burdigalian age and recorded sea-level changes, climatic and productivity events. Benthic foraminifera offered valuable data on the palaeoenvironmental evolution, with a large-scale progradational (coarsening up) sedimentary succession influenced by regional tectonics. The succession of depositional events include: i) transgressive coarse grained deposits with typical mediterranean assemblages of bivalves in beach environments; ii) the glauconitic facies which can be associated to the maximum flooding surface of the transgression; iii) the sedimentation continued on a narrow shelf influenced by deltas during the highstand; iv) influence of regional tectonics and subsequent filling with turbidites associated to fan deltas.

7

Plectoeratidus subarcticus, n.gen., n.sp., a new agglutinated foraminifer from the Upper Cretaceous of the western Barents Sea

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Kaminski M. A. , Setoyama E. , Tyszka J.

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tom Vol. 79, No 2

141-146

EN

We describe the new foraminiferal genus and species Plectoeratidus subarcticus n.gen. n.sp., from the Upper Cretaceous deep-water deposits of the Kviting and Kveite formations in the western Barents Sea. The genus is characterised by its planispiral-biserial-uniserial chamber arrangement, terminal aperture and lateral compre- ssion. The biometric analysis of test ontogenesis has been applied to document its dimorphism attributed to megalospheric and microspheric generations. This taxon may represent an evolutionary transition between the Cretaceous genera Spiroplectammina or Bolivinopsis and the Cenozoic genus Eratidus. The taxon appears to be endemic to the flysch-type agglutinated foraminiferal assemblages in the Norwegian Sea area.

8

Pliocene agglutinated benthic foraminifera from Site U1341 in the Bering Sea (IODP Expedition 323)

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Kaminski M. , Kender S. , Ciurej A. , Bălc R. , Setoyama E.

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tom Vol. 57, No. 2

335–-342

EN

We present the first record of benthic foraminiferal assemblages from 92 samples collected at approx. 3 m resolution in the bottom part of Hole U1341B drilled in the southern Bering Sea during Integrated Ocean Drilling Program (IODP) Expedition 323. Pliocene agglutinated foraminifera are generally rare within highly diatomaceous claystones occurring from the base of the hole at 601.87 m below sea floor (mbsf) to ~320 mbfs. The agglutinated foraminiferal assemblages are strongly dominated by the infaunal genera Eggerella, Karreriella, Martinottiella, and Spirosigmoilina. The calcareous-cemented Eggerella and Martinottiella are canaliculated with pores that are open to the test surface. Tubular agglutinated foraminifera are rare and are only found in isolated samples. The ecological information gained from this assemblage supports other proxy information indicating high levels of organic productivity and severely hypoxic conditions in the Bering Sea deep water during the Pliocene.

9

Palaeoecology of the Middle Miocene foraminifera of the Nowy Sącz Basin (Polish Outer Carpathians)

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Gonera M.

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2012

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tom Vol. 56, No 1

107-116

EN

Foraminifera from newly exposed outcrop sections located in a Middle Miocene piggyback basin of the Outer Carpathians Nowy Sącz Basin indicate an environment of normal saline waters on the inner shelf and a temperature not lower than 18oC. The area was ideal for the proliferation of: Miliolina spp., Elphidium crispum, Ammonia beccarii and Pararotalia. The habitat below the sediment surface was not colonised by foraminifera. Planktonic foraminifera are absent. The age of the population studied is referred based on the climate-related data, to the Orbulina suturalis Zone of the Miocene Climate Optimum.

10

Foraminiferal and calcareous nannoplankton biostratigraphy of the upper Badenian-lower Sarmatian strata in the SE Polish Carpathian Foredeep

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Peryt D. , Garecka M. , Peryt T. M.

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tom Vol. 65, No. 1

art. no. 18

EN

The Badenian/Sarmatian boundary in the Central Paratethys has been traditionally identified by the faunal turnover recording an important environmental change possibly controlled by the change from marine to brackish conditions. The strata below the Badenian/Sarmatian boundary in the northern Carpathian Foredeep are included into the Pecten beds, and those above it into the Syndesmya beds. Foraminiferal study of the Babczyn 2 borehole which is one of the crucial sections in the northern Carpathian Foredeep, well-known for the depositional age of rhyolite tuff within the Pecten beds dated by Śliwiński et al. (2012) at 13.06 ±0.11 Ma, indicated that in fact the boundary occurs within the Syndesmya beds. This conclusion is based upon the rapid change from a stenohaline foraminiferal fauna to a euryhaline one, and the appearance of the species Anomalinoides dividens, the taxon regarded as the marker for the Sarmatian. In the Babczyn 2 and Cieszanów 1 (located ~2.5 km basinward of Babczyn 2) boreholes, Anomalinoides dividens appears 3.1-3.8 m above the replacement of stenohaline by euryhaline foraminifers. The calcareous nannoplankton study shows that the upper Badenian and the lower Sarmatian strata in the studied sections represent the NN6, undivided NN6-NN7, and NN7 zones.

11

Carbon and oxygen isotope variability among foraminifera and ostracod carbonated shells

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Fourel F. , Martineau F. , Emoke Tóth E. , Görög A. , Escarguel G. , Lécuyer C.

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EN

This study investigates the effect of biological and environmental inter-individual variability on the meaning of d18O and d13C values acquired on small carbonated shells. First we present data obtained with a MultiPrep automated carbonate system on small sample sizes of a homogeneous carbonate material: Carrara marble. This demonstrates the capacities of the analytical system to reliably run small amounts of carbonates even down to 10 mg. Then we present two data sets obtained on real fossil samples of various size (sensu number of individual organisms) calibrated against the NBS19 carbonate standard. Both datasets evidence a clear trend of between-biological sample standard deviation increase for both d18O and d13C measurements when the number of pooled specimens per sample decreases. According to the results obtained from a systematic study of a geologically homogeneous sample of coeval fossil Elphidium foraminifera, we estimate that there is 95% of chances to reach between-biological sample standard deviation values higher than 1.02‰ (d18O) and 1.45‰ d13C) based on single-cell measurements. Such values are one order of magnitude higher than the instrumental standard deviations associated with these stable isotope ratios. Conversely, a minimum of 35 (d18O) and 44 (d13C) pooled specimens of Elphidium appears necessary to reach a between-sample standard deviation £ 0.25‰ with a probability of 95%. Such biological intrinsic and irreducible variability between coeval individuals, and thus samples, clearly questions the interest for single-cell analyses, more precisely, for coastal marine species, such as Elphidium, subject to many environmental changes during their life-time. Indeed, strong variations in salinity or temperature, as well as biogenic fractionation, could influence the isotopic composition of an individual specimen. Results might be less problematic for an average community including several tests. This paper underlines uncertainties linked to specific environments in which selected organisms live, especially for paleoceanographic or paleoclimatic reconstruction purposes where secular oxygen and carbon isotope variations typically range from 0.5 to 1.5‰.

12

Foraminiferal stratigraphy and palaeobathymetry of Paleocene-lowermost Oligocene deposits (Vezhany and Monastyrets nappes, Ukrainian Carpathians)

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Hnylko S. , Hnylko O.

Geological Quarterly

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2016

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tom Vol. 60, No. 1

77--105

EN

Mainly pelagic/hemipelagic deposits of the Vezhany Nappe (Paleocene-Lowermost Oligocene Metova Formation with a high content of planktonic foraminifera) and typical flysch deposits of the Monastyrets Nappe (Paleocene-Eocene Sushmanets Formation with common agglutinated foraminifera as well as the Eocene Drahovo Formation), of the southwestern inner part of the Ukrainian Carpathians have been studied. The Parvularugoglobigerina eugubina Zone (Lower Danian), Acarinina acarinata Zone (Upper Thanetian), Morozovella subbotinae Zone and Morozovella aragonensis Zone (Ypresian), Acarinina bullbrooki Zone and Acarinina rotundimarginata Zone (Lutetian), Subbotina corpulenta Zone and Subbotina vialovi Zone (Upper Priabonian – Lower Rupelian) based on planktonic foraminifera as well as the Rzehakina fissistomata sensu lato Zone (Paleocene), Glomospira charoides–Recurvoides smugarensis Zone (Ypresian), and an assemblage with Haplophragmoides parvulus (latest Mid Eocene-early Late Eocene) based on agglutinated foraminifera have been identified in these deposits. The deep-water agglutinated foraminifera of the “Rzehakina”, “Rhabdammina” and “Paratrochamminoides” assemblages found in the typical flysch deposits of the Sushmanets Formation indicate lower slope to abyssal environments below the CCD. The generic composition and morphological features of planktonic and benthic foraminifera recovered from marls of the Metova Formation suggest pelagic/hemipelagic conditions at bathyal depths above the foraminiferal lysocline.

13

Middle Miocene (Early Badenian) Amphistegina (Foraminiferida) from Olimpów (Central Paratethys, Poland)

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Gonera M.

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tom Vol. 82, No. 2

151–-159

EN

Specimens of Middle Miocene (Early Badenian) Amphistegina from the Polish Carpathians were examined. A section, sampled at the Olimpów quarry, displays chloralgal carbonates, rich in rhodolith nodules. Symbiont-bearing foraminifera (Amphistegina, Elphidium and Asterigerinata) constitute 15–57% of the total foraminifera assemblage. Amphistegina hauerina d’Orbigny, 1846 is the only species of the genus in the deposits studied. The sensitivity of larger foraminifera to water turbulence and light availability was applied in a reconstruction of the community habitat. The diameter and thickness of the Amphistegina tests indicate that the habitat was a zone of low light penetration and weak energy – a palaeoenvironment, similar to that of the modern A. radiata (Hottinger et al., 1993). Changes in the sphericity of the Amphistegina tests reflect a temporal drop of bathymetry in the middle part of the section. This is supported by other environmentally controlled features of the foraminiferal assemblage: the percentages of both planktonic and symbiont-bearing forms, as well as the proportions of robust and flat forms of Elphidium. It is possible that this variation in depth was due to eustatic changes in sea level, caused by Event Mi3 of the Middle Miocene climatic cooling. The spiral diameter of the test was at its lowest value then, indicating that maturity was reached at a faster rate. The period of shoaling offered the best life conditions for Amphistegina in this particular area.

14

Paleogene microfossils from the submarine debris flows in the Skole basin (Polish and Ukraine Outer Carpathians)

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Szydło A. , Garecka M. , Jankowski L. , Malata T.

Geology, Geophysics and Environment

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2014

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tom Vol. 40, no. 1

49--65

EN

Biostratigraphic analysis of fossils material has allowed the documentation of sediment gravity flows in the Skole basin during the Paleocene and Eocene times, and also in the Eocene-Oligocene transition. This most external basin of the NE Outer Carpathians was a marginal sea especially sensitive to geotectonic instability and relative sea-level change, favoring the development of down slope movements at these times. The dominance of calcareous forms in foraminifera, and a large share of redeposited species among the nanno- and microfossils indicate a close relationship of sediments containing them with the shelf environment and documents not too long transport. Additionally the recycled forms are often well preserved, indicating that the rock contained in flows were only plasticized and hydrated while the material itself was not a subject of significant mechanical processing in contrast to that one, which directly documented down slope moving. The latter forms are bad preserved and their fossil remains are usually corroded, partially dissolved and broken during this process. In addition, the planktonic forms including foraminifera, calcareous dinocysts and nannoplankton allow documenting the time of the final deposition of the sediment transported on slope.

15

Nowa metoda modelowania morfogenezy otwornic

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Tyszka J. , Topa P. , Łabaj P. , Alda W.

Przegląd Geologiczny

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2004

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tom Vol. 52, nr 1

80-83

EN

An overview of modeling methods of invertebrate shells as a background for modeling and visualization of mineral shells of foraminifera is presented. The recent authors propose more realistic methods of modeling. Our model introduces the moving reference approach to theoretical modeling of foraminiferal shells. This approach uses apertures as reference points, which move together with step-by-step growing chambers. Another important aspect of simulation is a random selection of parameters from the defined ranges of values. The resulted ``theoretical shells’’ closely mimic morphology and variability of recent and fossil foraminifera. The model is presented as an applet at http://www.icsr.agh.edu.pl/foraminifera . Future prospect includes an “emergent model”, gaining deeper insight into real morphogenetic processes.

16

Forainiferal biostratigraphy of the Egerian flysch sediments in the Silesian Nappe, Outer Carpathians, Polish part of the Bieszczady Mountains

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Bąk K.

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tom Vol. 75, No. 1

71--93

EN

Planktonic and benthic Foraminifera have been studied from the youngest deposits of the Krosno beds in the inner part of the Silesian Nappe (Outer Carpathians) in the Bieszczady Mountains. The studied part of the Krosno beds consists of Egerian (upper Oligocene–lower Miocene) flysch sediments, deposited within the Outer Carpathian Basin, a part of the Central Paratethys. Two interval zones: Tenuitella munda Zone and Globigeri- nelloides primordius Zone have been distinguished basing on the succession of planktonic Foraminifera. Additionally, Paragloborotalia inaequiconica Interval Subzone has been defined within the first one. Occurrence of calcareous nannoplankton, dinocyst assemblages and isochronous horizons of coccolith limestones (the Jasło Limestone and Zagórz Limestone) enabled correlation of the planktonic foraminiferal zones with chronostrati- graphy. The boundary between the two distinguished zones corresponds to the base of NN1 nannoplankton Zone (defined by the occurrence of Helicosphaera scissura) equivalent to the Oligocene/Miocene boundary. The base of the P. inaequiconica Subzone corresponds to the position of the Zagórz Limestone, refferred to NP 24 Zone (early Egerian). The benthic foraminiferal assemblages are dominated by bathyal, calcareous, hyaline, smooth-walled taxa, indicative of anoxic environment. The benthic assemblages remained relatively stable throughout the late Oligocene and were more diversified during the earliest Miocene, most probably in response to the oxygenation of bottom waters, due to the opening of new connections between the Central Paratethys and the Mediterranean region.

PL

W pracy przedstawiono zespoły otwornic egeru z najmłodszych utworów jednostki śląskiej w bieszczadzkiej części Karpat Zewnętrznych. Otwornice planktoniczne były podstawą do wydzielenia poziomów biostratygraficznych, których granice zostały porównane z danymi opartymi o wapienny nanoplankton (Garecka; w: Haczewski et al., A, B, oddane do druku) i dinocysty (Gedl; w: Haczewski et al., A, oddane do druku), a także odniesieniu ich do pozycji stratygraficznej dwóch chrohoryzontów - wapienia jasielskiego i wapienia z Zagórza. Praca niniejsza jest kontynuacją badań na tym obszarze (Bąk, 1999) i stanowi ich podsumowanie. Płaszczowina śląska jest na obszarze Bieszczadów zbudowana wyłącznie z warstw krośnieńskich (Fig. 1, 2) o miąższości ok. 3,5 km, w tym z ponad 1,3 km miąższości serią zawierającą gruboławicowe, grzbietotwórcze piaskowce otryckie. Ich obecność w warstwach krośnieńskich była podstawą do wyróżnienia w tej części jednostki śląskiej tzw. strefy bieszczadzkiej (lub strefy Otryt - Bitla), której długość wynosi ok. 150 km, a szerokość 15-20 km. W przekroju Bieszczadów strefa ta zbudowana jest z kilku łusek i fałdów, wśród których synklina Dźwiniacza Górnego zawiera bardzo miąższe i najmłodsze serie utworów fliszowych. Dotychczasowe prace stratygraficzne na tym obszarze (Haczewski et al., A, B oddane do druku) wskazywały na oligoceński wiek całej serii warstw krośnieńskich, w tym również warstw najmłodszych. W niniejszej pracy przedstawiono rezultaty opróbowania najmłodszej serii warstw krośnieńskich, tzw. warstw nadotryckich (oddział górny warstw krośnieńskich), które występują powyżej serii z piaskowcami otryckimi. Warstwy nadotryckie (maks. miąższość ok. 1050 m) tworzy seria silnie wapnistych, szarych i ciemnoszarych łupków marglistych, o charakterystycznej grubej (“mydlastej”) oddzielności, przeławicających się z wapnistymi, cienkoławicowymi, laminowanymi mułowcami i piaskowcami. Lokalnie wśród tej serii występują grube ławice piaskowców średnioziarnistych, bezstrukturalnych oraz pojedyncze, czarne serie z wirowcami (o miąższości 1-2 m). W najwyższej części warstw nadotryckich występuje jeden lub kilka soczewkowatych pakietów piaskowców średnioziarnistych, gruboławicowych, z laminacją równoległą, przekątną i konwolutną, o sumarycznej miąższości ok. 30 m. W niższej części warstw nadotryckich wykartowano ponadto 2 ważne dla stratygrafii horyzonty wapieni kokolitowych, tzw. wapień jasielski i wapień z Zagórza. W obrębie badanych utworów zostały one znalezione w obu skrzydłach synkliny Dźwiniacza Górnego. Wapienie te, znane z wielu miejsc w Karpatach Zewnętrznych są poziomami korelacyjnymi (Jucha, 1958; 1969, Koszarski & Żytko, 1959, 1961; Jucha & Kotlarczyk, 1961; Haczewski, 1984, 1989), a w niniejszej pracy są one ważnym elementem stratygrafii. Analizy mikropaleontologiczne wykorzystano na próbach pobranych z kilku profili w obrębie wspomnianej synkliny, tj.: w profilu Dźwiniacza Górnego (Fig. 3A, 4), w 2 profilach wokół Kiczery Dydiowskiej (Fig. 3B, 5) i w profilu Czereszni (Fig. 3C i 6). Ponadto wykorzystano dane z profilu Sanu w rejonie Dźwiniacza Górnego, będące wcześniej przedmiotem osobnej publikacji (Bąk, 1999). Zespoły otwornic opisano z kilku serii warstw nadotryckich, których granice stanowią horyzonty wapieni kokolitowych oraz wydzielono dodatkowo najwyższą część warstw nadotryckich, którą charakteryzuje odmienny zespół taksonów.

17

New data on middle and late Albian foraminifera and biostratigraphy of the northern palaeobiogeographical district of western Siberia

75%

Podobina V. M.

Geologos

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2015

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tom Vol. 21, No. 1

71--78

EN

The present paper discusses foraminiferal assemblages and biozones established on the basis of studies of samples from ten borehole sequences of the Khanty-Mansiysk Horizon in the Samotlor area of the northern palaeobiogeographical district of western Siberia (Russia). In this region, middle and late Albian foraminiferal assemblages were first distinguished in western Siberia. Levels from which these assemblages have been recovered, are here referred to the following foraminiferal zones, the Ammobaculites fragmentarius–Gaudryinopsis filiformis Zone (middle Albian) and the Ammotium braunsteini–Verneuilinoides borealis assanoviensis Zone (upper Albian). Zonal assemblages are dominated by representatives of the orders Ammodiscida, Textulariida and Ataxophragmiida. Species of the ataxophragmiid genera Verneuilinoides, Pseudoverneuilina and Gaudryinopsis are the most characteristic, inclusive of several key index forms. Foraminiferal tests consist of agglutinated quartz-silica, the wall microstructure being almost exclusively medium and coarse grained. In specific composition, the Albian assemblages from the Samotlor area are similar to those from Transuralia (Russia) and to the Canadian Province, which, together with West-Siberian Province, forms the Arctic palaeobiogeographical realm.

18

Modern agglutinated Foraminifera from the Hovgård Ridge, Fram Strait, west of Spitsbergen: evidence for a deep bottom current

75%

Kaminski M. A. , Niessen F.

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tom Vol. 85, No. 1

309--320

EN

Deep-water agglutinated foraminifera on the crest of the Hovgård Ridge, west of Spitsbergen, consist mostly of large tubular astrorhizids. At a boxcore station collected from the crest of Hovgård Ridge at a water depth of 1169 m, the sediment surface was covered with patches of large (1 mm diameter) tubular forms, belonging mostly to the species Astrorhiza crassatina Brady, with smaller numbers of Saccorhiza, Hyperammina, and Psammosiphonella. Non-tubular species consisted mainly of opportunistic forms, such as Psammosphaera and Reophax. The presence of large suspension-feeding tubular genera as well as opportunistic forms point to the presence of deep currents at this locality that are strong enough to disturb the benthic fauna. This is confirmed by data obtained from sediment echosounding, which exhibit lateral variation in relative sedimentation rates within the Pleistocene sedimentary drape covering the ridge, indicative of winnowing in a south-easterly direction.

19

Calibration of the Benthic Foraminiferal Oxygen Index in the Marmara Sea

75%

Kamiński M. A.

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2012

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tom Vol. 56, No. 4

757--764

EN

Benthic foraminifera (total assemblages) were studied from 30 sea-floor samples collected along a bathymetric transect on the southern shelf of the Marmara Sea from depths of 15–350 m. At each station, Kaiho’s Benthic Foraminiferal Oxygen Index (BFOI) was calculated based on species abundances using the methods outlined by Kaiho (1994). The calculated BFOI values were converted to analogue oxygen values, and calibrated to the dissolved oxygen values measured 1 m above the sea floor at each station. In the surface waters and central part of the Marmara Shelf transect, the BFOI values reproduce the measured dissolved oxygen values with a remarkable degree of accuracy. Beneath the pycnocline at depths of 30 to 75 m, the BFOI underestimated the measured oxygen values. This discrepancy is attributed to seasonally higher summer oxygen values within the chlorophyll maximum, corresponding to the position of the Mediterranean Inflow Water (MIW) present during summer. In the deeper part of the transect (below 140 m), BFOI values overestimated the measured oxygen values. This discrepancy is attributed to the presence of denser MIW that cascades down the submarine canyon beneath the Marmara ship channel during winter, ventilating the deep Marmara Sea. The BFOI accurately points out the seasonal differences in the position and depth of the MIW in the southwestern Marmara Sea. The BFOI likely reflects the longer-term oxygen values averaged over the span of many years.

20

The Pliensbachian/Toarcian boundary in the Almonacid de la Cuba section (Iberian Range, Spain)

75%

Goy A. , Comas-Rengifo J. , Gomez J. , Gonzales J. , Herrero C. , Palencia A. , Perilli N. , Rodrigo A.

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tom Vol. 4, no. 1

164-166

EN

The Almonacid de la Cuba section, representative of the Pliensbachian-Toarcian transition in the Iberian Range (Fig. 1), is reviewed. It is an expanded section where no important discontinuities have been detected. Four successive assemblages of ammonites, which are characterized by the presence of Pleuroceras (BH14-CU14), Canavaria (CU16-CU32), Dactylioceras (E.) (CU35.2-CU44) and Dactylioceras (O.) (CU44-CU87), are distinguished. The Pliensbachian/Toarcian boundary is located at the base of level CU35.2 with the first record of Dactylioceras (Fig. 2). These assemblages are mainly constituted by taxa typical of the NW European Province, such as Pleuroceras, Dactylioceras (O.) and P. paltum. However, frequent Mediterranean Province taxa such as Emaciaticeras, Canavaria, Lioceratoides, Neolioceratoides, Dactylioceras (E.) and P. madagascariense, are also recorded. In the Tenuicostatum Zone, dactylioceratidae are dominating with respect to harpoceratinae. In the Mirabile Subzone, species of Dactylioceras (E.) are coexisting with P. paltum. Brachiopods show two successive assemblages. The lower one is composed generally of the Pliensbachian taxa and the upper assemblage includes more endemic taxa. Coinciding with the Early Toarcian OAE, almost all these species disappeared at the end of the Tenuicostatum Chron. Foraminiferal assemblages are rich and diversified. Calcareous hyaline taxa are dominated by suborder Lagenina, agglutinated foraminifera are scarce, the suborders Spirillinina and Miliolina are represented by few specimens and taxa, and specimens of Robertinina have been recovered throughout the whole stratigraphic interval. The main biostratigraphical foraminiferal events can be recognized and compared with other sections of the Iberian Range and with another ones of selected NW European Basins. Ostracod assemblages of the Spinatum Zone are dominated by healdiids and cytheraceans, which decrease at the base of the Tenuicostatum Zone, where the cypridaceans are better represented. In the Semicelatum Subzone, coinciding with the disappearance of the healdiids, the cytheraceans become dominants.Calcareous nannofossils assemblages are rich and well preserved. This allowed locating precisely the biochronostratigraphical position of the main markers and events and comparing them with these recorded in other basins of Western Tethys. A magnetic polarity column for the Pliensbachian/Toarcian boundary has been constructed on the basis of the polarities of the 2C Component (Fig. 2). The lower boundary of the Toarcian is located within the R2 magnetozone. A relatively large magnetozone N3 of normal polarity is located within the Tenuicostatum Zone.