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Wyszukujesz frazę "ichnofabric" wg kryterium: Temat


Wyświetlanie 1-3 z 3
Tytuł:
Ichnofabric characterization in cores : a method of digital image treatment
Autorzy:
Rodríguez-Tovar, F. J.
Dorador, J.
Powiązania:
https://bibliotekanauki.pl/articles/191872.pdf
Data publikacji:
2015
Wydawca:
Polskie Towarzystwo Geologiczne
Tematy:
trace fossils
image treatment
ichnofabric approach
ichnofabric attributes and representations
Opis:
Ichnofabric analysis, as a relatively young ichnological approach, has witnessed rapid growth, showing its usefulness in basin analysis, with special attention to palaeoenvironmental interpretations. The ichnofabric approach has evolved from the description of trace composition and the intensity of bioturbation to integrate detailed information on numerous ichnofabric features, such as primary sedimentary structures, ichnological diversity, ichnological features, cross-cutting relation ships or tiering structures. This development has been associated with its application to the study of deep-sea sediments, especially in research on cores, which is not easy, owing to the particular features of cores. Here a method for improving ichnofabric characterization in modern marine cores is presented, on the basis of digital high-resolution image treatment, with special emphasis on the quantification of ichnofabric attributes. The proposed methodology is based on the modification of three image adjustments (image adjustment), the estimation of the percentage of the area occupied by bioturbation (digital estimation), the lateral and vertical quantification and comparison of pixel values for the infill of the trace fossils and the host sediment (pixel counting), and the integration of the information obtained in the visual representations of ichnofabrics (the ichnofabric representation). The sequential application of these proposed steps allow, 1) better identification of trace fossils, together with cross-cutting relation ships and the characterization of trace-fossil assemblages, 2) estimation of the percent age of bioturbation associated to each ichnotaxon, the whole ichnocoenosis, or a complete ichnofabric, 3) differentiation between biodeformational structures and trace fossils, discrimination between ichnotaxa, distinction between passively and actively infilled structures, and 4) evaluation of the depth of penetration by particular tracemakers.
Źródło:
Annales Societatis Geologorum Poloniae; 2015, 85, 3; 465-471
0208-9068
Pojawia się w:
Annales Societatis Geologorum Poloniae
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Disappeared almost without a trace : Taphonomic pathways and the recognition of hidden bioturbation events in Eocene storm deposits (Paují Formation, Lake Maracaibo, Venezuela)
Autorzy:
Buatois, L. A.
Delgado, M.
Mángano, M. G.
Powiązania:
https://bibliotekanauki.pl/articles/191974.pdf
Data publikacji:
2015
Wydawca:
Polskie Towarzystwo Geologiczne
Tematy:
trace fossils
ichnofabric
taphonomic pathways
tempestites
shallow marine
Eocene
Opis:
Shallow-marine deposits, included in the “Basal Sands” of the Eocene Paují Formation of the Maracaibo Basin in western Venezuela, record deposition in fore shore to lower off shore settings. These deposits are stacked in coarsening-upward parasequences that reflect variable intensities and frequencies of storms. Of particular interest are sharp-based, amalgamated, hummocky cross-stratified and rippled, very fine-grained sandstone beds, observed in the core MOT-X from the Motatán Field. These beds record storm deposition, under purely oscillatory to combined flows in an offshore-transition setting. The amalgamated nature of the sand stone interval indicates repeated erosion, due to multiple storm events. The ichnofabrics in these tempestites result from a distinctive taphonomic pathway, reflecting the interplay between bioturbation events and storm erosion and deposition. The storm-related trace-fossil suite is represented by Diplocraterion parallelum and local occurrences of Palaeophycus tubularis, Bergaueria isp. and Thalassinoides isp., which is consistent with the relatively high energy of formation of these deposits. Fair-weather deposits are absent from the sand stone interval. However, high densities of Chondrites isp. are present in the infills of Diplocraterion parallelum and, more rarely, Thalassinoides isp. providing the sole evidence of the establishment of a resident fauna during inter-storm intervals. Deposits containing the fair-weather suites were erosionally removed during the subsequent storm. The deep-tier emplacement of Chondrites and the ability of its producer to rework other biogenic structures favour preservation, allowing recognition of a “hidden” bioturbation event that otherwise might have remained undetected.
Źródło:
Annales Societatis Geologorum Poloniae; 2015, 85, 3; 473-479
0208-9068
Pojawia się w:
Annales Societatis Geologorum Poloniae
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
The significance of mudstone fabric combined with palaeoecological evidence in determining sedimentary processes - an example from Middle Jurassic of southern Poland
Autorzy:
Leonowicz, P. M.
Powiązania:
https://bibliotekanauki.pl/articles/2059717.pdf
Data publikacji:
2013
Wydawca:
Państwowy Instytut Geologiczny – Państwowy Instytut Badawczy
Tematy:
black mudstones
parallel lamination
storm deposits
ichnofabric
bottom oxygenation
Ore-Bearing Częstochowa Clay Formation
Opis:
Analysis of the fabric of laminated black mudstones of the Ore-Bearing Częstochowa Clay Formation (Bathonian, southern Poland) is used for reconstruction of sedimentary processes and conditions. Small-scale sedimentary features indicate that ore-bearing clays were deposited below storm-wave base in a shallow epicontinental sea, but structures reflecting quiet settling from suspension are not common. Most of recognized lamina types record the activity of bottom currents generated by storms. The benthic faunal association indicates that suboxic conditions prevailed on the seafloor, restricting infaunal activity to cryptobioturbation. Recurrent short-lived reoxygenetion events, linked probably to storms, resulted in the development of dysoxic conditions, recorded by a more diverse trace fossil association (consisting of Chondrites, Trichichnus, pyritized burrows, Palaeophycus and Protovirgularia) and colonization of the seafloor by epifaunal bivalves (Bositra). Truly anoxic conditions might have been briefly established, leading to mass mortality of Bositra.
Źródło:
Geological Quarterly; 2013, 57, 2; 243--260
1641-7291
Pojawia się w:
Geological Quarterly
Dostawca treści:
Biblioteka Nauki
Artykuł
    Wyświetlanie 1-3 z 3

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