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Wyszukujesz frazę "shallow marine" wg kryterium: Temat


Wyświetlanie 1-4 z 4
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:
Coniacian-?Santonian paralic sedimentation in the Rakowice Małe area of the North Sudetic Basin, SW Poland: sedimentary facies, ichnological record and palaeogeographical reconstruction of an evolving marine embayment
Autorzy:
Leszczyński, S.
Powiązania:
https://bibliotekanauki.pl/articles/191916.pdf
Data publikacji:
2010
Wydawca:
Polskie Towarzystwo Geologiczne
Tematy:
shallow marine
paludal
lagoonal
brackish enironments
bioturbation
ichnofossils
Cretaceous
Lower Silesia
Polska
Opis:
The Coniacian-?Santonian siliciclastic succession outcropped in a sandstone quarry at Rakowice Małe (Żerkowice Member of the Rakowice Wielkie Formation, and the Czerna Formation including the Nowogrodziec Member; North Sudetic Basin, SW Poland) provides an interesting example of paralic deposits. Lithofacies and ichnofossil examination indicate coastal, lacustrine, paludal and lagoonal sedimentation. Valuable new data are supplied by trace fossils, a feature not considered yet in the literature on the Upper Cretaceous of the North Sudetic Basin. Trace fossils are overall abundant in the upper part of the Nowogrodziec Member and overlying part of the Czerna Formation. The following ichnogenera: Thalassinoides, Ophiomorpha, Asterosoma, Palaeophycus, Planolites, Skolithos, Teredolites, Chondrites, Cylindrichnus, Arenicolites, Rosselia, Teichichnus, Phycodes, Phycosiphon, and Schaubcylindrichnus are represented. The trace fossils represent the Skolithos, Teredolites and Cruziana ichnofacies. The Cruziana Ichnofacies is typified by the richest trace fossil assemblage characteristic of its archetypal, proximal and stressed expressions. An upper shoreface to foreshore origin of these sediments is documented using lithofacies and the ichnofossils Ophiomorpha and Thalassinoides in the exposed part of the Żerkowice Member. Dominance of kaolinite, lack of burrows and upward passage into paludal deposits is interpreted to indicate a lacustrine origin of variegated clayey mudstone at the base of the Nowogrodziec Member. The changes of depositional environments are interpreted as resulting from separation of the area from the open sea by a sand barrier formed due to the termination of the forced regression. Siltstones containing plant roots and fragments of drifted wood showing the trace fossil Teredolites clavatus, together with coal-seams containing Thalassinoides isp., are assigned to indicate a coastal plain, paludal deposition of the overlying part of the Nowogrodziec Member and incursion of marine waters. The fining upward sequence constituting the top part of the Nowogrodziec Member and showing almost archetypal Cruziana Ichnofacies substituted by its expression indicative of highly stressed, brackish conditions are shown to indicate extensive drowning of the area and lagoonal sedimentation. Termination of the drowning, embodied in a maximum flooding surface, is indicated in a bed of coaly mudstone at the top of the Nowogrodziec Member. Sedimentation on a periodically prograded brackish bay shoreface is inferred from lithofacies, ichnofossils and body fossils for the deposits overlying the Nowogrodziec Member and topping the examined succession. The trace fossils indicate Cruziana Ichnofacies and Skolithos Ichnofacies in the expression of slightly stressed environ- ments. The whole examined part of the Czerna Formation is interpreted as a fifth-order transgressive-regressive cycle.
Źródło:
Annales Societatis Geologorum Poloniae; 2010, 80, No 1; 1-24
0208-9068
Pojawia się w:
Annales Societatis Geologorum Poloniae
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Late Cretaceous palaeogeography of NE Bohemian Massif : diachronous sedimentary successions in the Wleń Graben and Krzeszów Brachysyncline (SW Poland)
Autorzy:
Kowalski, Aleksander
Powiązania:
https://bibliotekanauki.pl/articles/1836017.pdf
Data publikacji:
2021
Wydawca:
Polskie Towarzystwo Geologiczne
Tematy:
Sudetic epi-Variscan cover
shallow-marine palaeostrait
wave-dominated sedimentation
tidal currents
offshore transition
Opis:
This paper provides a new sedimentological and palaeogeographic interpretation of the Late Cretaceous (late Cenomanian to early Coniacian) shallow-marine succession exposed in the Wleń Graben and in the Krzeszów Brachysyncline (NE Bohemian Massif, Sudetic Block). These two tectonic subunits are outliers of the North Sudetic and Intra-Sudetic synclinoriums, respectively, and contain relics of the diachronous sedimentary succession of a seaway linking the Boreal and Tethyan marine provinces during the Late Cretaceous. Results of sedimentological study and facies analysis show that the late Cenomanian sedimentation within this corridor was dominated by strong in situ reworking of the pre-Cretaceous bedrock driven by storm waves and possibly tidal currents. In the latest Cenomanian, siliciclastic sedimentation was followed by the deposition of offshore-transition to offshore muddy calcareous facies in the Krzeszów area, while the deposition of coarse-grained siliciclastic facies continued in the Wleń area. The nearshore clastic belt in the latter area changed into a wider strait dominated by offshore sedimentation in the early Turonian, whereby the interconnected Wleń and Krzeszów passages evolved into a uniform strait of fully-marine sedimentation. In the middle Turonian, the southern part of the strait became progressively filled with coarse-grained siliciclastic material supplied from the east. At the end of the late Turonian and in the early Coniacian, the strait funnelled bi-directional tidal currents along its axis. The youngest Cretaceous strata in the Wleń area comprise erosional relics of the early Coniacian shoreface to offshore-transition deposits. The younger Cretaceous deposits are unpreserved, probably eroded during the post-Santonian(?) tectonic inversion of the Wleń–Krzeszów strait. Despite the relatively small distance between the two relic parts of the strait, the shallow-marine succession reveals distinct diachroneity on a regional scale, reflecting an interplay of eustatic changes, differential tectonic subsidence and clastic sediment supply. This paper presents the first detailed sedimentological logs from the two study areas, with new findings of fossil fauna and flora, proposes a new palaeogeographic interpretation and discusses the influence and development of the source areas for the Cretaceous Sudetic Wleń–Krzeszów marine strait at the NE fringe of the Bohemian Massif.
Źródło:
Annales Societatis Geologorum Poloniae; 2021, 91, 1; 1-26
0208-9068
Pojawia się w:
Annales Societatis Geologorum Poloniae
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Ichnology of the Cambrian Ociesęki Sandstone Formation (Holy Cross Mountains, Poland)
Autorzy:
Stachacz, M.
Powiązania:
https://bibliotekanauki.pl/articles/191282.pdf
Data publikacji:
2016
Wydawca:
Polskie Towarzystwo Geologiczne
Tematy:
Cambrian
trace fossils
shallow-water marine deposition
Holy Cross Mountains
Opis:
Quartz arenites and wackes with intercalations of silty shales of the Ociesęki Formation were analysed in small outcrops and one core. The succession contains about forty-three ichnogenera and seventy-four ichnospe- cies, among which thirty-three ichnogenera and fifty-three ichnospecies are described by present author. The formation belongs to the Schmidtiellus-Holmia Superzone and to the Protolenus-Issafeniella Zone. Most strata are totally bioturbated. The diverse and numerous trace fossils represent the Cruziana ichnofacies in the lower part of the formation and the Skolithos ichnofacies in the upper part. A few possibly new ichnospecies of different ichnogenera have been described in open nomenclature. Sedimentary structures and trace fossil assemblages indicate that the older part of this formation was deposited on the upper offshore to lower shoreface, while its younger part was deposited on the lower to middle shoreface, where storm episodes were the main factor controlling sedimentation and the activity of benthos. The trace fossil associations studied are similar to those from the lower Cambrian in many places around the world. The ichnoassociations from the Polish part of the East European Platform and from Sweden, which represent the Baltica palaeocontinent, display the closest similarity.
Źródło:
Annales Societatis Geologorum Poloniae; 2016, 86, 3; 291-328
0208-9068
Pojawia się w:
Annales Societatis Geologorum Poloniae
Dostawca treści:
Biblioteka Nauki
Artykuł
    Wyświetlanie 1-4 z 4

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