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    Wyświetlanie 1-5 z 5
    Tytuł:
    Adjustment coefficients for planimetric analysis of the granulometry of coarse-grained sediments
    Autorzy:
    Pisarska-Jamroży, Małgorzata
    Kossowski, Tomasz
    Jamroży, Jerzy
    Powiązania:
    https://bibliotekanauki.pl/articles/94642.pdf
    Data publikacji:
    2011
    Wydawca:
    Uniwersytet im. Adama Mickiewicza w Poznaniu
    Tematy:
    grain-size distribution
    planimetric analysis
    coarse-grained sediments
    skład granulometryczny
    analiza planimetryczna
    osady gruboziarniste
    Opis:
    The relationship between results from granulometric analyses of by sieving and by planimetry was investigated by numerical simulation of cubes filled with boulders, cobbles and pebbles. Cross-sections through the sediment were simulated and compared with photos of an actual outcrop wall. Volumes estimated on the basis of planimetric analysis using the cross-sections were compared with sieve analyses, thus allowing to determine adjustment coefficients. The coefficients for pebbles and cobbles have a small standard error, but are larger for boulders, which might be a consequence of too small areas formed by the cross-sections.
    Źródło:
    Geologos; 2011, 17, 4; 221-226
    1426-8981
    2080-6574
    Pojawia się w:
    Geologos
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Alternative interpretations of grain-size data from Quaternary deposits
    Autorzy:
    Mycielska-Dowgiałło, Elżbieta
    Ludwikowska-Kędzia, Małgorzata
    Powiązania:
    https://bibliotekanauki.pl/articles/94466.pdf
    Data publikacji:
    2011
    Wydawca:
    Uniwersytet im. Adama Mickiewicza w Poznaniu
    Tematy:
    Quaternary deposits
    grain-size distribution
    cumulative curve
    frequency curves
    textural parameters
    osady czwartorzędowe
    skład granulometryczny
    parametry teksturale
    Opis:
    Several possibilities to present and to interpret the results of granulometric analyses of Quaternary fluvial, aeolian, glacial and wash-out slope deposits were investigated. Attention is paid particularly to the cumulative curves at a probability scale and the frequency curves, and it is shown how these curves can help to determine the sedimentary environment. The inclination of the cumulative curves in the part of the maximum proportion of a particular grain size appears significant. It appears possible to obtain information on the density and dynamics of the transporting medium from the course of the cumulative curves (inclination and spread of grain size). The examination of textural parameters allows to draw regression lines characteristic of both deposits from various sedimentary environments and deposits from one single environment but with different histories as to their transport dynamics.
    Źródło:
    Geologos; 2011, 17, 4; 189-203
    1426-8981
    2080-6574
    Pojawia się w:
    Geologos
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Granulometric and facies analysis of Middle–Upper Jurassic rocks of Ler Dome, Kachchh, western India: an attempt to reconstruct the depositional environment
    Autorzy:
    Ghaznavi, Asma A.
    Quasim, M. A.
    Ahmad, A. H. M.
    Ghosh, Sumit K.
    Powiązania:
    https://bibliotekanauki.pl/articles/94565.pdf
    Data publikacji:
    2019
    Wydawca:
    Uniwersytet im. Adama Mickiewicza w Poznaniu
    Tematy:
    grain size analysis
    hydrodynamic conditions
    microtexture
    sedimentation
    marine environment
    analiza wielkości ziarna
    warunki hydrodynamiczne
    mikrotekstura
    sedymentacja
    środowisko morskie
    Opis:
    Grain size analysis is an important sedimentological tool used to unravel hydrodynamic conditions, mode of transportation and deposition of detrital sediments. For the present study, detailed grain size analysis was carried out in order to decipher the palaeodepositional environment of Middle–Upper Jurassic rocks of the Ler Dome (Kachchh, western India), which is further reinforced by facies analysis. Microtextures were identified as grooves, straight steps and V-shaped pits, curved steps and solution pits suggesting the predominance of chemical solution activity. Grain size statistical parameters (Graphic and Moment parameters) were used to document depositional processes, sedimentation mechanisms and conditions of hydrodynamic energy, as well as to discriminate between various depositional environments. The grain size parameters show that most of the sandstones are medium- to coarse-grained, moderately to well sorted, strongly fine skewed to fine skewed and mesokurtic to platykurtic in nature. The abundance of medium- to coarse-grained sandstones indicates fluctuating energy levels of the deposition medium and sediment type of the source area. The bivariate plots show that the samples are mostly grouped, except for some samples that show a scattered trend, which is either due to a mixture of two modes in equal proportion in bimodal sediments or good sorting in unimodal sediments. The linear discriminant function analysis is predominantly indicative of turbidity current deposits under shallow-marine conditions. The C-M plots indicate that the sediments formed mainly by rolling to bottom suspension and rolling condition in a beach subenvironment. Log probability curves show that the mixing between the suspension and saltation populations is related to variable energy conditions.
    Źródło:
    Geologos; 2019, 25, 1; 51-73
    1426-8981
    2080-6574
    Pojawia się w:
    Geologos
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Textural characteristics, mode of transportation and depositional environment of the Stormberg Group in the Eastern Cape, South Africa: evidence from grain size and lithofacies analyses
    Autorzy:
    Chima, Priscilla
    Baiyegunhi, Christopher
    Powiązania:
    https://bibliotekanauki.pl/articles/2204351.pdf
    Data publikacji:
    2022
    Wydawca:
    Uniwersytet im. Adama Mickiewicza w Poznaniu
    Tematy:
    grain size distribution
    textural parameters
    lithofacies classification
    hydrodynamic energy conditions
    Triassic
    Jurassic
    rozkład wielkości ziarna
    parametry teksturalne
    klasyfikacja litofacji
    warunki hydrodynamiczne
    warunki energetyczne
    trias
    jura
    Opis:
    The Stormberg Group comprises the Molteno, Elliot and Clarens formations and is one of four stratigraphical groups that make up the Karoo Supergroup in South Africa. The group is the highest unit in the Karoo Basin, representing the final phase of preserved sedimentation. The major problem with the Stromberg Group is that the mode of transport, hydrodynamic energy conditions and depositional environment are still poorly understood. For the present paper, grain size and lithofacies studies on selected sandstones from the Molteno, Elliot and Clarens formations were performed so as to elucidate their textural characteristics, depositional processes, sedimentation mechanisms and hydrodynamic energy conditions and to discriminate different depositional environments. The statistical parameters of grain size distribution (mean grain size, standard deviation, skewness and kurtosis) show that the sandstones are predominantly unimodal, fine grained, moderately well sorted, mesokurtic and near symmetrical. The bivariate diagrams of the aforementioned statistical parameters demonstrate that river and aeolian dune had the greatest impact on the depositional environments. Likewise, the C-M pattern (Passega diagram) shows that the sandstones were mostly deposited through tractive current process. Furthermore, the C-M diagram reveals the prevalence of rolling, suspension and graded suspension modes of sediment transportation. Seventeen sedimentary lithofacies were identified and grouped into seven lithofacies associations. These lithofacies associations indicate braided channel, overbank and swamp deposits for the Molteno Formation, alluvial fan/floodplain and playa deposits for the Elliot Formation and aeolian deposits for the Clarens Formation.
    Źródło:
    Geologos; 2022, 28, 1; 61--78
    1426-8981
    2080-6574
    Pojawia się w:
    Geologos
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Texture and composition of the Rosa Marina beach sands (Adriatic coast, southern Italy): a sedimentological/ecological approach
    Autorzy:
    Moretti, M.
    Tropeano, M.
    van Loon, A. J.
    Acquafredda, P.
    Baldacconi, R.
    Festa, V.
    Lisco, S.
    Mastronuzzi, G.
    Moretti, V.
    Scotti, R.
    Powiązania:
    https://bibliotekanauki.pl/articles/94295.pdf
    Data publikacji:
    2016
    Wydawca:
    Uniwersytet im. Adama Mickiewicza w Poznaniu
    Tematy:
    source-area reconstruction
    grain-size analysis
    mineralogical composition
    image analysis
    coastal erosion
    texture
    composition
    beach sands
    Rosa Marina
    Adriatic coast
    southern Italy
    rekonstrukcja obszaru źródłowego
    analiza wielkości ziarna
    skład mineralogiczny
    analiza obrazu
    erozja wybrzeża
    tekstura
    skład
    piasek plażowy
    wybrzeże Adriatyku
    południowe Włochy
    Opis:
    Beach sands from the Rosa Marina locality (Adriatic coast, southern Italy) were analysed mainly microscopically in order to trace the source areas of their lithoclastic and bioclastic components. The main cropping out sedimentary units were also studied with the objective to identify the potential source areas of lithoclasts. This allowed to establish how the various rock units contribute to the formation of beach sands. The analysis of the bioclastic components allows to estimate the actual role of organisms regarding the supply of this material to the beach. Identification of taxa that are present in the beach sands as shell fragments or other remains was carried out at the genus or family level. Ecological investigation of the same beach and the recognition of sub-environments (mainly distinguished on the basis of the nature of the substrate and of the water depth) was the key topic that allowed to establish the actual source areas of bioclasts in the Rosa Marina beach sands. The sedimentological analysis (including a physical study of the beach and the calculation of some statistical parameters concerning the grain-size curves) shows that the Rosa Marina beach is nowadays subject to erosion.
    Źródło:
    Geologos; 2016, 22, 2; 87-103
    1426-8981
    2080-6574
    Pojawia się w:
    Geologos
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
      Wyświetlanie 1-5 z 5

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