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    Wyświetlanie 1-9 z 9
    Tytuł:
    Sferule z granicy Kreda-Paleogen (Lechówka, Polska) – wstępne dane
    Spherules from the Cretaceous–Paleogene boundary (Lechówka, Polska) – preliminary data
    Autorzy:
    Brachaniec, Tomasz
    Szopa, Krzysztof
    Karwowski, Łukasz
    Krzykawski, Tomasz
    Salamon, Mariusz
    Brom, Krzysztof
    Powiązania:
    https://bibliotekanauki.pl/articles/1033022.pdf
    Data publikacji:
    2015
    Wydawca:
    Polskie Towarzystwo Meteorytowe
    Tematy:
    Cretaceous–Paleogene boundary
    impact origin
    smectite
    spherule
    spinel
    Opis:
    Samples of boundary clay from Cretaceous–Paleogene deposits from Lechówka, Poland were examined for spherules to confirm the impact origin of the sediment. The chemical composition of investigated spherules show similarities to material from the K–Pg boundary from Stevns Klint. The impact genesis of the spherules is confirmed by the presence of nickel-rich spinel grains on their surfaces. The deposits with spherules are built by smectite with Al and Mg enrichment. This cheto smectite is forming as a result of the weathering of the impact glass.
    Źródło:
    Acta Societatis Metheoriticae Polonorum; 2015, 6; 17-22
    2080-5497
    Pojawia się w:
    Acta Societatis Metheoriticae Polonorum
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Dinoflagellate cysts and palynofacies across the Cretaceous-Paleogene boundary interval of the Vrancea Nappe (Eastern Carpathians, Romania)
    Autorzy:
    Țabără, D.
    Slimani, H.
    Powiązania:
    https://bibliotekanauki.pl/articles/2060343.pdf
    Data publikacji:
    2017
    Wydawca:
    Państwowy Instytut Geologiczny – Państwowy Instytut Badawczy
    Tematy:
    Vrancea Nappe
    dinoflagellate cyst biostratigraphy
    palynofacies
    Cretaceous-Paleogene boundary interval
    Opis:
    A palynological study of uppermost Maastrichtian to Lower Paleocene depos i ts from a stratigraphic section of the Vrancea Nappe (Eastern Carpathians), reveals the presence of diverse and well-preserved dinoflagellate cyst assemblages. The biostratigraphic interpretation of these dinocyst assemblages suggests that (1) the Cretaceous-Paleogene boundary lies within a ~8 m thick sedimentary interval, between the Lepşa Formation (uppermost Maastrichtian) and Putna-Piatra Uscată Formation (Lower Danian), based on the Last Appearance Datum of latest Maastrichtian markers such as Pterodinium cretaceum and Palynodinium cf. grallator and on the First Appearance Datum of Danian markers such as Senoniasphaera inornata, Xenicodinium lubricum, Tectatodinium rugulatum and Eisenackia circumtabulata, and (2) a discontinuity between the two formations. The palynofacies analysis from this geological section indicates an abundance of continental organic matter (mainly opaque phytoclasts), deposited in a distal setting of the sedimentary basin. The occurtences in the palynological assemblage of some oceanic dinocyst taxa such as Impagidinium and Pterodinium suggest the same depositional environment for the geological formations analysed.
    Źródło:
    Geological Quarterly; 2017, 61, 1; 39--52
    1641-7291
    Pojawia się w:
    Geological Quarterly
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Fragmenty kopalnego meteorytu z Lechówki: charakterystyka mineralogiczna i geochemiczna
    Fragments of strongly weathered meteorite from Lechówka: mineralogical and geochemical characterisation
    Autorzy:
    Szopa, Krzysztof
    Karwowski, Łukasz
    Krzykawski, Tomasz
    Brachaniec, Tomasz
    Powiązania:
    https://bibliotekanauki.pl/articles/1033087.pdf
    Data publikacji:
    2017
    Wydawca:
    Polskie Towarzystwo Meteorytowe
    Tematy:
    Cretaceous-Paleogene boundary
    Lechówka
    fossil iron meteorites
    kamacite
    meteorites
    paleometeorite
    schreibersite
    taenite
    Opis:
    Fossil iron meteorites are extremely rare in the geological sedimentary record. In the boundary clay from the outcrop at the Lechówka quarry (Poland), fragments of the paleometeorite were found in the Cretaceous-Paleogene boundary clay layer. The fragments of meteorite (2–6 mm in size) and meteoritic dust are metallic-grey in colour. Analyses of the meteorite from Lechówka reveal the presence of Ni-rich minerals with a total Ni amount of 2–3 wt%. They are represented by: taenite, kamacite, schreibersite, Ni-rich magnetite, and Ni-rich goethite. The investigated remnants of paleometeorite apparently represent an independent fall and does not seem to be derived from the K-Pg impactor.
    Źródło:
    Acta Societatis Metheoriticae Polonorum; 2017, 8; 100-109
    2080-5497
    Pojawia się w:
    Acta Societatis Metheoriticae Polonorum
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Upper Cretaceous (Maastrichtian) charophyte gyrogonites from the Lameta Formation of Jabalpur, Central India: palaeobiogeographic and palaeoecological implications
    Autorzy:
    Khosla, A.
    Powiązania:
    https://bibliotekanauki.pl/articles/138589.pdf
    Data publikacji:
    2014
    Wydawca:
    Polska Akademia Nauk. Czytelnia Czasopism PAN
    Tematy:
    charophyta
    palaeobotany
    palaeogeography
    biogeography
    Cretaceous-Paleogene boundary
    Charophyta
    paleobotanika
    paleogeografia
    biogeografia
    kreda
    paleogen
    granica
    Opis:
    A charophyte gyrogonite assemblage consisting of Platychara cf. sahnii, Nemegtichara grambastii and Microchara sp. is reported herein from two localities (Bara Simla Hill and Chui Hill sections) of the Lameta Formation at Jabalpur. The Lameta Formation locally underlying the Deccan traps has been shown to be pedogenically modified alluvial plain deposits containing one of the most extensive dinosaur nesting sites in the world. They are associated with dinosaur bones and freshwater ostracod assemblages that suggest a Late Cretaceous (Maastrichtian) age. This is the first detailed systematic account of charophyte gyrogonites from the Lameta Formation. This charophyte assemblage is compatible with the biostratigraphic attribution provided by the ostracods. From a biogeographic viewpoint, it exhibits considerable similarity to other infratrappean assemblages of the Nand, Dongargaon, and Dhamni-Pavna sections (Maharashtra), and some intertrappean assemblages of Kora in Gujarat, Rangapur in Andhra Pradesh and Gurmatkal in South India. Globally, the genus Microchara is well distributed throughout Eurasia, whereas the genus Platychara occurs richly in the Upper Cretaceous deposits of Europe, Asia, America and Africa. However, at the specific level, Platychara cf. sahnii shows close affinities with charophytes from the Maastrichtian of Iran whilst Nemegtichara grambastii shows distinct affinities with two species of Early Palaeogene deposits of China and Mongolia. The presence of charophyte gyrogonites in the Lameta sediments is attributed to local lacustrine and palustrine conditions within a flood plain environment.
    Źródło:
    Acta Geologica Polonica; 2014, 64, 3; 311-323
    0001-5709
    Pojawia się w:
    Acta Geologica Polonica
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Sedimentary development and isotope analysis of deposits at the Cretaceous/Palaeogene transition in the Paraíba Basin, NE Brazil
    Autorzy:
    Neumann, Virgínio Henrique
    Barbosa, José Antônio
    Nascimento-Silva, Valberlândia Maria
    Sial, Alcides Nobrega
    Filho, Mario
    Powiązania:
    https://bibliotekanauki.pl/articles/94597.pdf
    Data publikacji:
    2009
    Wydawca:
    Uniwersytet im. Adama Mickiewicza w Poznaniu
    Tematy:
    NE Brazil
    Cretaceous-Paleogene boundary
    carbon isotopes
    oxygen isotopes
    Brazylia
    izotop węgla
    izotop tlenu
    Opis:
    New data are presented for three formations (Itamaracá, Gramame and Maria Farinha) and two boundaries (Campanian/Maastrichtian and Maastrichtian/Danian) in the Olinda Sub-basin of the Paraíba Basin. Currently accepted facies models, sequence stratigraphy characterizations, and stable-isotope data of carbon and oxygen are reviewed. The carbonate cement of the Itamaracá Formation sandstones shows carbon- and oxygen-isotope ratios consistent with a shallow-marine depositional environment: δ18O ranges from -0.8 to -2.7‰ PDB, and δ13C ranges from +1 to +2‰ PDB. Within the Itamaracá Formation, a maximum flooding surface at the Campanian/Maastrichtian transition has been identified. During the Maastrichtian, a Highstand System Tract was deposited, which shows an increase in temperature and marine bioproductivity as recorded by stable-isotope values (δ18O from -3 to -5‰ PDB, and δ13C values of -1.2, -0.3, 0.1 and +2.3‰ PDB). Just below the K/Pg boundary, the O-isotope signal indicates three warming phases, alternating with four cooling phases.
    Źródło:
    Geologos; 2009, 15, 2; 103-113
    1426-8981
    2080-6574
    Pojawia się w:
    Geologos
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Spherules associated with the Cretaceous–Paleogene boundary in Poland
    Autorzy:
    Brachaniec, T.
    Karwowski, Ł.
    Szopa, K.
    Powiązania:
    https://bibliotekanauki.pl/articles/139277.pdf
    Data publikacji:
    2014
    Wydawca:
    Polska Akademia Nauk. Czytelnia Czasopism PAN
    Tematy:
    Cretaceous-Paleogene boundary
    Polska
    Spherule
    microkrystites
    impact origin
    Ni-rich spinels
    smectite
    kreda
    paleogen
    granica
    Polska
    geneza uderzeniowa
    smektyty
    Opis:
    The succession of the Lechówka section near Chełm in south-eastern Poland presents the first complete record of the Cretaceous–Paleogene (K–Pg) boundary in Poland. Samples of the boundary clay were examined for microtektites and shocked minerals to confirm the impact origin of the sediment. The spheroidal fraction reveals morphological and mineralogical features, e.g., spherules, similar to material from the K–Pg boundary as described from elsewhere. The impact genesis of the spherules is confirmed by the presence of nickel-rich spinel grains on their surfaces. The spinels are considered to be primary microlites and, thus, the spherules at Lechówka can be classified as microkrystites. No shocked minerals were noted. The deposits with spherules comprise Aland Mg-rich smectite (Cheto smectite). This almost pure Mg-rich smectite, forming up to 100% of the clay fraction, derived from the weathering of the impact glass. It is proposed that the spherules isolated from the Cretaceous-Paleogene boundary clay at Lechówka come from the Chicxulub crater in Mexico.
    Źródło:
    Acta Geologica Polonica; 2014, 64, 1; 99-108
    0001-5709
    Pojawia się w:
    Acta Geologica Polonica
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Dinoflagellate cysts, palynofacies and organic geochemistry of the Cretaceous-Palaeogene (K–Pg) boundary transition at the Ellès section, northeastern Tunisia
    Autorzy:
    M’Hamdi, A.
    Slimani, H.
    Ismail-Lattrache, K. B.
    Ali, W. B.
    Powiązania:
    https://bibliotekanauki.pl/articles/191365.pdf
    Data publikacji:
    2014
    Wydawca:
    Polskie Towarzystwo Geologiczne
    Tematy:
    Cretaceous-Paleogene (K-Pg) boundary
    dinoflagellate cysts
    palynofacies
    organic matter
    EllÀs section
    Tunisia
    Opis:
    A palynofacies study carried out across the Cretaceous–Palaeogene (K–Pg) boundary in the El Haria Formation at Ellès, northeastern Tunisia, revealed the presence of organic matter dominated by marine palynomorphs, mainly dinoflagellate cyst assemblages. Continental palynomorphs (sporomorphs) and amorphous organic matter (AOM) are also present in all samples. The total organic carbon (TOC) content is generally less than 0.7 wt.%. The Rock-Eval S1 parameters vary from 0.01 to 0.3 mgHC/g rock. The Rock-Eval S2 parameters vary from 0.15 to 0.57 mgHC/g rock. The hydrogen index (HI) and oxygen index (OI) values range from 61 to 214 mgHC/g TOC and 149 to 638 mgHC/g TOC, respectively. The Tmax values range from 420 to 440°C. The TOC, Rock-Eval pyrolysis and palynofacies analyses indicate that the El Haria Formation is characterized by immature organic matter type II and III and a low thermal alteration index (TAI). Also, the authors present in this paper the biostratigraphic, palaeoenvironmentl and palaeobiogeographic framework for the dinoflagellate cyst assemblages below and above the Cretaceous–Palaeogene boundary in the Ellès section.
    Źródło:
    Annales Societatis Geologorum Poloniae; 2014, 84, 3; 185-212
    0208-9068
    Pojawia się w:
    Annales Societatis Geologorum Poloniae
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Short-term survival of ammonites in New Jersey after the end-Cretaceous bolide impact
    Autorzy:
    Landman, N.H.
    Garb, M.P.
    Rovelli, R.
    Ebel, D.S.
    Edwards, L.E.
    Powiązania:
    https://bibliotekanauki.pl/articles/22198.pdf
    Data publikacji:
    2012
    Wydawca:
    Polska Akademia Nauk. Instytut Paleobiologii PAN
    Tematy:
    short-term survival
    ammonite
    New Jersey
    Cretaceous
    bolide impact
    Ammonoidea
    biostratigraphy
    extinction
    Paleogene
    boundary
    Opis:
    A section containing the Cretaceous/Paleogene (= Cretaceous/Tertiary) boundary in Monmouth County, New Jersey, preserves a record of ammonites extending from the end of the Cretaceous into possibly the beginning of the Danian. The section includes the upper part of the Tinton Formation and lower part of the Hornerstown Formation. The top of the Tinton Formation is represented by a richly fossiliferous unit (the Pinna Layer) that contains many bivalves in life position as well as ammonite jaws preserved inside body chambers. Ammonites include Pachydiscus (Neodesmoceras) mokotibensis, Sphenodiscus lobatus, Eubaculites carinatus, E. latecarinatus, Discoscaphites iris, D. sphaeroidalis, D. minardi, and D. jerseyensis. The Pinna Layer probably represents a relatively short interval of time lasting tens to hundreds of years; it is conformably overlain by the Burrowed Unit, which contains a single fragment of Discoscaphites sp. and several fragments of E. latecarinatus, as well as several isolated specimens of ammonite jaws including two of Eubaculites. Examination of the mode of preservation of the ammonites and jaws suggests that they were fossilized during deposition of the Burrowed Unit and were not reworked from older deposits. Based on the ammonites and dinoflagellates in the Pinna Layer and the Burrowed Unit, these strata traditionally would be assigned to the uppermost Maastrichtian, corresponding to calcareous nannofossil Subzone CC26b. However, a weak iridium anomaly (500–600 pg/g) is present at the base of the Pinna Layer, which presumably represents the record of the bolide impact. Correlation with the iridium layer at the Global Stratotype Section and Point at El Kef, Tunisia, would, therefore, imply that these assemblages are actually Danian, provided that the iridium anomaly is in place and the ammonites and dinoflagellates are not reworked. If the iridium anomaly is in place, or even if it has migrated downward from the top of the Pinna Layer, the ammonites would have survived the impact at this site for a brief interval of time lasting from a few days to hundreds of years.
    Źródło:
    Acta Palaeontologica Polonica; 2012, 57, 4
    0567-7920
    Pojawia się w:
    Acta Palaeontologica Polonica
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    The Alvarez impact theory of mass extinction; limits to its applicability and the "great expectations syndrome"
    Autorzy:
    Racki, G.
    Powiązania:
    https://bibliotekanauki.pl/articles/20155.pdf
    Data publikacji:
    2012
    Wydawca:
    Polska Akademia Nauk. Instytut Paleobiologii PAN
    Tematy:
    Alvarez impact theory
    mass extinction
    great expectation syndrome
    bolide impact
    extraterrestrial marker
    impact crater
    Cretaceous
    Paleogene
    Triassic
    Jurassic
    Frasnian
    Famennian
    boundary
    Opis:
    For the past three decades, the Alvarez impact theory of mass extinction, causally related to catastrophic meteorite impacts, has been recurrently applied to multiple extinction boundaries. However, these multidisciplinary research efforts across the globe have been largely unsuccessful to date, with one outstanding exception: the Cretaceous–Paleogene boundary. The unicausal impact scenario as a leading explanation, when applied to the complex fossil record, has resulted in force−fitting of data and interpretations (“great expectations syndrome”). The misunderstandings can be grouped at three successive levels of the testing process, and involve the unreflective application of the impact paradigm: (i) factual misidentification, i.e., an erroneous or indefinite recognition of the extraterrestrial record in sedimentological, physical and geochemical contexts, (ii) correlative misinterpretation of the adequately documented impact signals due to their incorrect dating, and (iii) causal overestimation when the proved impact characteristics are doubtful as a sufficient trigger of a contemporaneous global cosmic catastrophe. Examples of uncritical belief in the simple cause−effect scenario for the Frasnian–Famennian, Permian–Triassic, and Triassic–Jurassic (and the Eifelian–Givetian and Paleocene–Eocene as well) global events include mostly item−1 pitfalls (factual misidentification), with Ir enrichments and shocked minerals frequently misidentified. Therefore, these mass extinctions are still at the first test level, and only the F–F extinction is potentially seen in the context of item−2, the interpretative step, because of the possible causative link with the Siljan Ring crater (53 km in diameter). The erratically recognized cratering signature is often marked by large timing and size uncertainties, and item−3, the advanced causal inference, is in fact limited to clustered impacts that clearly predate major mass extinctions. The multi−impact lag−time pattern is particularly clear in the Late Triassic, when the largest (100 km diameter) Manicouagan crater was possibly concurrent with the end−Carnian extinction (or with the late Norian tetrapod turnover on an alternative time scale). The relatively small crater sizes and cratonic (crystalline rock basement) setting of these two craters further suggest the strongly insufficient extraterrestrial trigger of worldwide environmental traumas. However, to discuss the kill potential of impact events in a more robust fashion, their location and timing, vulnerability factors, especially target geology and palaeogeography in the context of associated climate−active volatile fluxes, should to be rigorously assessed. The current lack of conclusive impact evidence synchronous with most mass extinctions may still be somewhat misleading due to the predicted large set of undiscovered craters, particularly in light of the obscured record of oceanic impact events.
    Źródło:
    Acta Palaeontologica Polonica; 2012, 57, 4
    0567-7920
    Pojawia się w:
    Acta Palaeontologica Polonica
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
      Wyświetlanie 1-9 z 9

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