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Wyświetlanie 1-2 z 2
Tytuł:
The Early Kimmeridgian succession at Kodrąb (Radomsko elevation, central Poland) and its palaeogeographical and palaeotectonic implications
Autorzy:
Wierzbowski, A.
Głowniak, E.
Powiązania:
https://bibliotekanauki.pl/articles/2060417.pdf
Data publikacji:
2018
Wydawca:
Państwowy Instytut Geologiczny – Państwowy Instytut Badawczy
Tematy:
Radomsko elevation
Early Kimmeridgian
ammonite stratigraphy
palaeogeography
synsedimentary tectonics
Opis:
The Early Kimmeridgian succession in the Rogaszyn Quarry at Kodrąb (Radomsko elevation) represents mostly shallow-water carbonate platform deposits that, over wide areas of central Poland were controlled by the activity of the tectonic zone being the prolongation of the Holy Cross lineament. The ammonites collected enable precise recognition of ammonite zones – the Platynota and the Hypselocyclum zones, some subzones and horizons. The precise dating enables detailed correlation of the particular units of the succession with those recognized at the eastern and northern borders of the Wieluń Upland and the NW margin of the Holy Cross Mts. The deposits at Kodrąb from the top of the Planula Zone, through the Platynota Zone, up to the lower part of the Hypselocyclum Zone, reveal markedly smaller thicknesses equaling ~15–20% of those of coeval deposits from the adjoining areas. The differences in sedimentary evolution at Kodrąb during the Early Kimmeridgian resulted mostly from local synsedimentary tectonic movements of fault blocks. Beginning from the late Hypselocyclum Chron, these differences markedly diminished, which resulted from the uniform subsidence of a wider area, and disappearance of the shallow-water deposits of the carbonate platforms, being replaced by deeper-water deposits of the Burzenin Formation.
Źródło:
Geological Quarterly; 2018, 62, 3; 509--521
1641-7291
Pojawia się w:
Geological Quarterly
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
A potential stratotype for the Oxfordian/Kimmeridgian boundary: Staffin Bay, Isle of Skye, UK
Autorzy:
Wierzbowski, A.
Coe, A.
Hounslow, M.
Matyja, B.
Ogg, J.
Page, K.
Wierzbowski, H.
Wright, J.
Powiązania:
https://bibliotekanauki.pl/articles/2061313.pdf
Data publikacji:
2006
Wydawca:
Państwowy Instytut Geologiczny – Państwowy Instytut Badawczy
Tematy:
ammonite succession
Oxfordian/Kimmeridgian boundary
microfossils
isotope stratigraphy
magnetostratigraphy
Opis:
A coastal exposure of the Staffin Shale Formation at Flodigarry, Staffin Bay, Isle of Skye, Scotland, UK fulfils the criteria for definition as the Global Stratotype Section and Point (GSSP) for the base of the Kimmeridgian Stage (Upper Jurassic). This marine shale succession was deposited during a long-term transgression, and is part of a complete, relatively well-expanded stratigraphic succession. A rich fauna of ammonites above and below the Oxfordian/Kimmeridgian boundary allows recognition of the Evoluta Subzone (Pseudocordata Zone) and Rosenkrantzi Subzone (Rosenkrantzi Zone) of the Subboreal and Boreal uppermost Oxfordian, and the Densicostata Subzone (Baylei Zone) and the Bauhini Zone of the Subboreal and Boreal lowermost Kimmeridgian). A suitable level for the boundary is thus marked by the replacement of the Subboreal Ringsteadia (M)/Microbiplices (m) by Pictonia (M)/Prorasenia (m), and by the first appearance of Boreal Amoeboceras (Plasmatites). Detailed study of the microfossils reveals an excellent dinoflagellate succession. A variety of stratigraphically important dinoflagellates are found, the assemblages being intermediate in character between Boreal and Subboreal ones. The magnetostratigraphic data, though rather troublesome to extract, shows a polarity pattern which can be confidently correlated to other UK boundary sections. The upper boundary of a normal magnetozone falls at, or very near, the proposed Oxfordian/Kimmeridgian boundary. The 87Sr/86Sr ratio at the boundary, based on an analysis of belemnites, lies between 0,70689 and 0,70697, averaging 0.70693. Matching worldwide trends, no distinct change in the ratio is seen across the boundary. A lack of variations in the carbon isotope composition of belemnites across the Oxfordian/Kimmeridgian boundary does not indicate perturbation in the global carbon cycle. However, high ?13C values and their scatter suggest the influence of local fractionation affecting isotope composition of dissolved inorganic carbon (DIC) in the partly isolated Boreal sea. A fall in the belemnite ?18O values in the Upper Oxfordian and Lower Kimmeridgian compared to the Mid Oxfordian suggests a slight rise in seawater temperature.
Źródło:
Volumina Jurassica; 2006, 4, 1; 17-33
1896-7876
1731-3708
Pojawia się w:
Volumina Jurassica
Dostawca treści:
Biblioteka Nauki
Artykuł
    Wyświetlanie 1-2 z 2

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