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    Wyświetlanie 1-7 z 7
    Tytuł:
    Micromorphology of modern tills in southwestern Spitsbergen – insights into depositional and post-depositional processes
    Autorzy:
    Skolasińska, Katarzyna
    Rachlewicz, Grzegorz
    Szczuciński, Witold
    Powiązania:
    https://bibliotekanauki.pl/articles/2046798.pdf
    Data publikacji:
    2016
    Wydawca:
    Polska Akademia Nauk. Czytelnia Czasopism PAN
    Tematy:
    Arctic
    microstructures
    postdepositional changes
    subglacial till
    supraglacial till
    Svalbard
    Źródło:
    Polish Polar Research; 2016, 37, 4; 435-456
    0138-0338
    2081-8262
    Pojawia się w:
    Polish Polar Research
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Elsterian ice sheet dynamics in a topographically varied area (southern part of the Racibórz–Oświęcim Basin and its vicinity, southern Poland)
    Autorzy:
    Salamon, T.
    Powiązania:
    https://bibliotekanauki.pl/articles/2060370.pdf
    Data publikacji:
    2017
    Wydawca:
    Państwowy Instytut Geologiczny – Państwowy Instytut Badawczy
    Tematy:
    ice sheet dynamic
    fore-mountain area
    subglacial till
    Elsterian Glaciation
    Ostrava Basin
    Opis:
    During the Elsterian Glaciation, the Scandinavian Ice Sheet, before reaching its maximum extent, advanced over the mountainous foreland of Southern Poland, which was characterized by a substrate of increasingly varied relief. One such area was the hilly Rybnik Plateau of the southern part of the Racibórz–Oświęcim Basin, located directly north of the Ostrava Basin and Moravian Gate, where the ice sheet advanced far south and formed a large lobe. In this study, till from the Łaziska site, located in southern part of the Rybnik Plateau, was analysed and interpreted. The till was deposited at the top of an W–E oriented ridge composed of Neogene clays. The study indicates that a high basal water pressure occurred at the base of the ice sheet, favouring a basal mechanism of ice sheet movement. Till fabric and kinematic structures indicate that ice flowed easily from the west over the ridge, parallel to its axis. Reconstructed patterns of ice flow direction reflect an ice sheet that was characterized by a strong spatially varied dynamics. The Odra Valley was the main corridor of fast flowing ice to the Ostrava Basin, from where ice was distributed radially in different directions. The second corridor of actively flowing ice was probably located in the Ruda palaeovalley to the north of the Rybnik Plateau. In the central part of the Rybnik Plateau, ice flow was restricted. This less dynamic ice sheet behaviour resulted mostly from the much higher location of the area. This study indicates that the large morphological and lithological variations of the ice sheet substrate induced varied frictional resistance, producing a spatially varied stress field within the ice sheet. This generated active zones of streaming ice adjacent to more passive zones. Potential switching between neighbouring active zones transporting ice towards the ice sheet margin is postulated.
    Źródło:
    Geological Quarterly; 2017, 61, 2; 465--479
    1641-7291
    Pojawia się w:
    Geological Quarterly
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Mikromorfologia glin lodowcowych jako narzędzie w rekonstrukcji procesów subglacjalnych
    Micromorphology of tills as a tool in reconstructing subglacial processes
    Autorzy:
    Narloch, W.
    Piotrowski, J. A.
    Powiązania:
    https://bibliotekanauki.pl/articles/2075061.pdf
    Data publikacji:
    2013
    Wydawca:
    Państwowy Instytut Geologiczny – Państwowy Instytut Badawczy
    Tematy:
    micromorphology
    S-matrix microstructures
    subglacial till
    subglacial processes
    mikromorfologia
    mikrostruktura S-matrix
    glina lodowcowa
    proces zlodowacenia
    Opis:
    Micromorphology has become an important tool in investigations of glacial tills. Structure and texture of tills studied in thin sections can be used to decipher the origin of tills, in particular their depositional and deformational history, but also to shed light on the nature of subglacial erosion, transport and deposition processes in general. In combination with laboratory experiments on till shearing under controlled conditions, micromorphology yields useful, quantitative data on till rheology that helps understanding the processes of ice movement over soft, deformable beds.This paper is a review of micromorphology applications to the study of subglacial tills as reported in the leading modern literature and presentation of a case study from Obórki site in north-central Poland that illustrates the potential of this method in the context of the last Scandinavian Ice Sheet.
    Źródło:
    Przegląd Geologiczny; 2013, 61, 5; 294--303
    0033-2151
    Pojawia się w:
    Przegląd Geologiczny
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Zróżnicowanie facjalne glin jako wskaźnik fluktuacji ciśnienia wód subglacjalnych na kontakcie lodu i podłoża podczas zlodowacenia wisły w północnej części Pojezierza Dobrzyńskiego
    Till facies diversity as an indicator of subglacial water pressure fluctuations at the ice/bed interface during Weichselian glaciation in N part of Dobrzyń Lakeland
    Autorzy:
    Narloch, W.
    Wojciechowska, J. M.
    Osowicka, A.
    Wysota, W.
    Piotrowski, J.A.
    Sobiech, M.
    Powiązania:
    https://bibliotekanauki.pl/articles/294428.pdf
    Data publikacji:
    2013
    Wydawca:
    Stowarzyszenie Geomorfologów Polskich
    Tematy:
    glina subglacjalna
    poślizg bazalny
    deformacja podłoża
    Pojezierze Dobrzyńskie
    subglacial till
    basal sliding
    bed deformation
    Dobrzyń Lakeland
    Opis:
    Badaniom sedymentologicznym poddano gliny lodowcowe fazy poznańskiej zlodowacenia wisły na dwóch stanowiskach terenowych (Przeszkoda i Obórki), zlokalizowanych w północnej części Pojezierza Dobrzyńskiego. Podczas ostatniego zlodowacenia obszar ten był pokryty lobem lodowcowym Wisły, którego rozwój był najprawdopodobniej determinowany przez wiślany strumień lodowy. W rekonstrukcji procesów formowania glin oraz mechanizmów ruchu lodu została zastosowana kompleksowa analiza glin, w tym: cech sedymentacyjnych, uziarnienia, składu petrograficznego, orientacji dłuższej osi głazików oraz analiza mikromorfologiczna. Analizowane gliny są masywne i warstwowane. Badania sugerują występowanie złożonych i czasowo zmiennych warunków pod lobem Wisły, prawdopodobnie spowodowanych przez fluktuacje ciśnienia wód subglacjalnych. Ruch lodu był wynikiem kombinacji deformacji podłoża i poślizgu bazalnego.
    Sedimentological analyses were performed on glacial till of the Weichselian glaciation in two field sites (Przeszkoda and Obórki) which are located in northern part of the Dobrzyń Lakeland. During the last glaciation this area was covered by the Vistula ice lobe which development has been determined by the Vistula Ice Stream. A multi-proxy approach including a study of sedimentary features, grain size, petrographic composition, till fabric and till micromorphology was used in reconstruction of till formation and ice movement mechanisms. Analysed tills are massive and stratified. We suggest existing of complex and temporally variable conditions under the Vistula ice lobe, probably caused by subglacial water fluctuations. Ice movement was caused by a combination of bed deformation and basal sliding.
    Źródło:
    Landform Analysis; 2013, 25; 125-133
    1429-799X
    Pojawia się w:
    Landform Analysis
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Basal till and subglacial conditions at the base of the Upper Odra Lobe (southern Poland) during the Odranian Glaciation
    Autorzy:
    Salamon, T.
    Powiązania:
    https://bibliotekanauki.pl/articles/2060468.pdf
    Data publikacji:
    2014
    Wydawca:
    Państwowy Instytut Geologiczny – Państwowy Instytut Badawczy
    Tematy:
    till
    subglacial conditions
    ice-sheet dynamics
    Upper Odra Lobe
    Pleistocene
    Southern Poland
    Opis:
    The objective of this contribution is detail characteristics of the basal till and the conditions in the base of Upper Odra Lobe. The lobe was formed in a foremountain area. Its central part was a Niemodlin Plain and the W part of the Racibórz Basin, surrounded by areas that have a much more varied relief.Particular attention is paid to the conditions at the ice sheet base, generatingthe dynamics ofglaciermovement. The study is based on analysis of the basal till. Three sites with basal till lying on different types of substratum (more typical for the study area) are presented. The basal till of the Upper Odra Lobe is characterized by spatial variations. Different intensities of its deformation indicate that large lateral differences in conditions occurred in the lobe substratum. The lithology controlled the rate of basal water pressure, and thus the strength of both the subglacial sediments and the ice-bed coupling. Various strain rates in the till profiles indicate that the conditions at the ice-sheet base also changed with time. The ice sheet was highly mobile, even on the coarse-grained substratum. The low permeability of the Quaternary substratum, and the relatively small thickness of the Quaternary sands and gravels resulted in a high water pressure at the ice-sheet base. The movement of the Upper Odra Lobe was concentrated in the basal zone of the ice sheet. The main mechanism of basal motion was sliding and deformation of the subglacial sediments. Deformation probably occurred in restricted areas and did not have a pervasive character.
    Źródło:
    Geological Quarterly; 2014, 58, 4; 779--794
    1641-7291
    Pojawia się w:
    Geological Quarterly
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Unravelling the complex nature of the Upper Weichselian till section at Gdynia Babie Doły, northern Poland
    Autorzy:
    Woźniak, P. P.
    Czubla, P.
    Powiązania:
    https://bibliotekanauki.pl/articles/94576.pdf
    Data publikacji:
    2016
    Wydawca:
    Uniwersytet im. Adama Mickiewicza w Poznaniu
    Tematy:
    subglacial processes
    till fabric
    till petrography
    Gulf of Gdańsk
    Pleistocene
    Fennoscandian Ice Sheet
    procesy podlodowcowe
    Zatoka Gdańska
    Pleistocen
    pokrywa lodowa
    Opis:
    The complexity of glacial sequences may increase when these formed underneath ice sheets despite subsequent changes in their extent that are accompanied by alterations in the direction of the ice flow. Our aim was to determine whether or not changes in ice sheet dynamics during the Late Weichselian are also recorded in sediments formed north of the area of its fluctuating margin (i.e., where the ice sheet prevailed independent of such fluctuations). It is shown that in these areas such a record could have occurred, as documented by results of till studies at Babie Doły. The examination was carried out using several analyses: lithofacies properties of sediments, petrographic till composition (fine gravel fraction, indicator erratics), till matrix CaCO3 content, till fabric, as well as orientation of striae on the top surfaces of large clasts. In parallel, datings of sub- and supra-till sediments using the TL method were carried out. The basal till at Babie Doły represents almost the entire Upper Weichselian, but it can be divided into subunits whose features indicate different ice flow directions and debris supply. The lower subunit developed as a result of the palaeo-ice stream along the main axis of the Baltic Sea (from the north), expanding to areas adjacent to the depression of the Gulf of Gdańsk. The upper subunit developed when the influence of the palaeo-ice stream in the study area decreased, the main role having been taken over by the ice flowing from the northwest. The till analysed also shows considerable lateral variation, indicative of the mosaic nature of subglacial sedimentation. We consider the diversity of permeability of deposits over which the ice sheet extended to be the prime factor that determined such a situation.
    Źródło:
    Geologos; 2016, 22, 1; 15-32
    1426-8981
    2080-6574
    Pojawia się w:
    Geologos
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Zastosowanie mikrotomografii komputerowej do badania orientacji klastów w glinach lodowcowych
    Application of computed microtomography in clast orientation studies in glacial tills
    Autorzy:
    Hermanowski, Piotr
    Duda, Piotr
    Powiązania:
    https://bibliotekanauki.pl/articles/2075992.pdf
    Data publikacji:
    2019
    Wydawca:
    Państwowy Instytut Geologiczny – Państwowy Instytut Badawczy
    Tematy:
    mikrotomografia
    gliny lodowcowe
    drumlin
    procesy subglacjalne
    stargardzkie pole drumlinowe
    microtomography
    glacial till
    subglacial processes
    Stargard drumlin field
    Opis:
    Limitations of macroscopic measurements and observations of glacial tills, no matter how informative they are, have contributed to the development of micromorphological analysis first in thin sections, since the 80’s using X-ray computed tomography, and recently X-ray computed microtomography (μ-CT). The цCT has found wide applications in science including earth sciences where is used for imagining various geological samples in the 3D view. The sampling procedure and preparation of samples do not generate much effort, and eventually, allow analysis of samples with a preserved undisturbed structure. Herein, we present a short review and methodology of μCT as well as its application to the study of glacial tills. For example, we analyzed a subglacial till sample from the lee side of a drumlin located in the Stargard drumlin field area, NW Poland. The results show a distinctive bimodal pattern of clast fabrics which is interpreted as a result of subglacial till squeezing. Smaller clasts are obliquely oriented to the major direction of the ice flow whereas the larger clasts orientation is approximately in accordance with the major shear stress direction. Overall, our data emphasize the potential of the μ-CT in glacial till studies.
    Źródło:
    Przegląd Geologiczny; 2019, 67, 8; 653--661
    0033-2151
    Pojawia się w:
    Przegląd Geologiczny
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
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