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Wyszukujesz frazę "Quaternary" wg kryterium: Temat


Wyświetlanie 1-7 z 7
Tytuł:
The nature of the Pleistocene-Holocene palaeosols in the Gaza Strip, Palestine
Autorzy:
Ubeid, Khalid F.
Powiązania:
https://bibliotekanauki.pl/articles/94360.pdf
Data publikacji:
2011
Wydawca:
Uniwersytet im. Adama Mickiewicza w Poznaniu
Tematy:
hamra
palaeosols
palaeoclimate
Quaternary
Gaza
gleby kopalne
paleoklimat
czwartorzęd
Opis:
The Pleistocene to Holocene succession in the Gaza Strip, Palestine, consists of an alternation of calcareous sandstones and reddish fine-grained deposits (palaeosols). The palaeosols can be subdivided into two main groups based on the sand-sized versus clay- to silt-sized grains: (1) the sandy hamra palaeosols, and (2) the loess and loess-derived palaeosols. The hamra palaeosols can, in turn, also be subdivided into two main types according to their colour and grain size: (1) light brown loamy to sandy hamra palaeosols, and (2) dark brown sandy clay hamra palaeosols. The hamra palaeosols are polygenetic and originated in humid environments. Their red colour results from ferric oxides coating the sand grains, but also by illuviation. The various pedogenitic units and their gradual transition to loess palaeosols are due to different phases of dust accretion. Both groups of palaeosols developed during the last glacial. They are considered to represent different climate environments: hamra palaeosols represent humid climates, whereas the loess and loess-derived palaeosols represent dry and semi-dry climates.
Źródło:
Geologos; 2011, 17, 3; 163-173
1426-8981
2080-6574
Pojawia się w:
Geologos
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Quaternary deposits and weathered bedrock material as a source of dangerous radon emissions in Estonia
Autorzy:
Petersell, V.
Jüriado, K.
Raukas, A.
Shtokalenko, M.
Täht-Kok, K.
Powiązania:
https://bibliotekanauki.pl/articles/94608.pdf
Data publikacji:
2015
Wydawca:
Uniwersytet im. Adama Mickiewicza w Poznaniu
Tematy:
radon
uranium
klint
graptolite argillite
Quaternary deposits
till
uran
argilit
osady czwartorzędowe
Opis:
The risk of dangerous radon emissions in Estonia is high, being among the highest in Europe. In almost 33 per cent of Estonian land area, the content of radon in soil-contained air exceeds the safe limit for unrestricted construction (50 kBq/m3). In such high radon-risk areas the concentration of radon in soil-contained air ranges from 50 to 400 kBq/m3, in a few cases reaching up to 2,100 kBq/m3 exceeding the permitted level for residential areas. The situation is particularly serious in the northernmost part of the country, where uranium-rich graptolite argillite (Dictyonema shale) and the Obolus phosphorite are close to ground surface and their particles are constituent parts of Quaternary deposits. Radon emissions from bedrock have been investigated in detail, but to date Quaternary strata as a source of radon emissions are poorly studied. According to our measurements the highest concentrations of radon are related to tills containing clasts and fines of graptolite argillite and phosphorite. Glacial deposits include also granitoidal material, containing U, Th and K, which have been transported by glaciers from the outcrop areas of crystalline basement rocks in Finland and the Gulf of Finland. Due to weathering, outwash and repeated redeposition other genetic types are poorer in radioactive elements and they are weaker sources of radon.
Źródło:
Geologos; 2015, 21, 2; 139-147
1426-8981
2080-6574
Pojawia się w:
Geologos
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
The assemblages of transparent heavy minerals in Quaternary sediments of the Kielce-Łagów Valley (Holy Cross Mountains, Poland)
Autorzy:
Ludwikowska-Kędzia, Małgorzata
Powiązania:
https://bibliotekanauki.pl/articles/94365.pdf
Data publikacji:
2013
Wydawca:
Uniwersytet im. Adama Mickiewicza w Poznaniu
Tematy:
heavy mineral analysis
Quaternary deposits
Holy Cross Mountains
analiza ciężkich minerałów
złoża czwartorzędowe
Góry Świętokrzyskie
Opis:
The composition of the transparent heavy-mineral assemblages (0.25-0.1 mm) in Quaternary slope, karst, glacial, fluvioglacial and fluvial deposits with different parent material was investigated in the Kielce-Łagów Valley (the central part of the Palaeozoic core of the Holy Cross Mountains). For the purpose, 93 samples of mostly sandy sediments were examined. Some marker and some supporting minerals can be distinguished. Slope and karst deposits are dominated by the abrasion-resistant minerals zircon, tourmaline, staurolite and rutile. This assemblage points at a source consisting of strongly weathered pre-Quaternary bedrock. Glacial and fluvioglacial deposits are dominated by medium-resistant and non-resistant minerals (garnet, amphibole, pyroxene and biotite). The two types of parent material of the heavy minerals are typical of the Quaternary deposits in the Polish uplands. The two sources are most clear in the younger (Vistulian and Holocene), mostly fluvial sediments. The results of the analysis imply that the impact of Pleistocene glaciers on the central part of the Holy Cross Mountains was neither large enough to hide the local mineralogical background, nor sufficient to dominate over the main processes transforming the mineral composition under the variable climatic conditions of the Quaternary, including aeolian processes and chemical weathering.
Źródło:
Geologos; 2013, 19, No. 1-2; 95-129
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:
Grain-size distribution analysis of Quaternary sediments from the southern part of the Lodz region in Poland: a computational-methods approach
Autorzy:
Wachecka-Kotkowska, Lucyna
Kotkowski, Paweł
Powiązania:
https://bibliotekanauki.pl/articles/94333.pdf
Data publikacji:
2011
Wydawca:
Uniwersytet im. Adama Mickiewicza w Poznaniu
Tematy:
granulometric analysis
skewness
kurtosis
computational methods
Quaternary sediments
central Poland
analiza granulometryczna
skośność
kurtoza
metody komputerowe
osady czwartorzędowe
Polska
Opis:
Eighteen samples of Quaternary unconsolidated sediments from the Piotrków Plateau and the Radomsko Hills in central Poland have been analysed for their average grain size, sorting, skewness and kurtosis. The analysis was carried out by seven computational methods of interpolation and nine extrapolation methods. It appears that linear interpolation, the traditional method (DOS), and the Josek and Gradistat Programs give comparable results, but that quadratic interpolation and the method of moments should not be applied since they yield unreliable results. The method of moments gives unduly high or unduly low parameter values because of the application of different, i.e. incomparable measures in the applied formulae. It should be stressed that only extrapolation provides, if performed under the right conditions, the possibility to determine some parameters, in particular skewness values.
Źródło:
Geologos; 2011, 17, 4; 205-219
1426-8981
2080-6574
Pojawia się w:
Geologos
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Evolution of Early Pleistocene fluvial systems in central Poland prior to the first ice sheet advance – a case study from the Bełchatów lignite mine
Autorzy:
Goździk, J.
Zieliński, T.
Powiązania:
https://bibliotekanauki.pl/articles/94398.pdf
Data publikacji:
2017
Wydawca:
Uniwersytet im. Adama Mickiewicza w Poznaniu
Tematy:
Quaternary
preglacial
fluvial-aeolian interaction
heavy minerals
quartz grain morphology
sedimentology
palaeoclimate
Czwartorzęd
preglacjał
minerały ciężkie
morfologia ziarna kwarcu
sedymentologia
paleoklimat
Opis:
Deposits formed between the Neogene/Pleistocene transition and into the Early Pleistocene have been studied, mainly on the basis of drillings and at rare, small outcrops in the lowland part of Polish territory. At the Bełchatów lignite mine (Kleszczów Graben, central Poland), one of the largest opencast pits in Europe, strata of this age have long been exposed in extensive outcrops. The present paper is based on our field studies and laboratory analyses, as well as on research data presented by other authors. For that reason, it can be seen as an overview of current knowledge of lowermost Pleistocene deposits at Bełchatów, where exploitation of the Quaternary overburden has just been completed. The results of cartographic work, sedimentological, mineralogical and palynological analyses as well as assessment of sand grain morphology have been considered. All of these studies have allowed the distinction of three Lower Pleistocene series, i.e., the Łękińsko, Faustynów and Krzaki series. These were laid down in fluvial environments between the end of the Pliocene up to the advance of the first Scandinavian ice sheet on central Poland. The following environmental features have been interpreted: phases of river incision and aggradation, changes of river channel patterns, source sediments for alluvia, rates of aeolian supply to rivers and roles of fluvial systems in morphological and geological development of the area. The two older series studied, i.e., Łękińsko and Faustynów, share common characteristics. They were formed by sinuous rivers in boreal forest and open forest environments. The Neogene substratum was the source of the alluvium. The younger series (Krzaki) formed mainly in a braided river setting, under conditions of progressive climatic cooling. Over time, a gradual increase of aeolian supply to the fluvial system can be noted; initially, silt and sand were laid down, followed by sand only during cold desert conditions. These fluvio-periglacial conditions are identified in the foreground of the advance of the oldest ice sheet into this part of central Poland. The series studied have been compared with other fluvial successions which accumulated in the Kleszczów Graben during subsequent glaciations so as to document general changes in fluvial systems as reactions to climatic evolution. Thus, a palaeoenvironmental scenario has emerged which could be considered to be characteristic of central Poland during the Early Pleistocene.
Źródło:
Geologos; 2017, 23, 2; 89-107
1426-8981
2080-6574
Pojawia się w:
Geologos
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
River response to climate and sea level changes during the Late Saalian/Early Eemian in northern Poland – a case study of meandering river deposits in the Chłapowo cliff section
Autorzy:
Moskalewicz, D.
Sokołowski, R. J.
Fedorowicz, S.
Powiązania:
https://bibliotekanauki.pl/articles/94416.pdf
Data publikacji:
2016
Wydawca:
Uniwersytet im. Adama Mickiewicza w Poznaniu
Tematy:
point-bar succession
meandering fluvial system
Quaternary geology
fluvial sedimentology
Eemian Sea
następstwo odsypu meandrowego
meandrujący system rzeczny
geologia czwartorzędu
sedymentologia rzeczna
morze eemskie
Opis:
Fluvial sediments in the Chłapowo cliff section were studied in order to reconstruct their palaeoflow conditions and stratigraphical position. Lithofacies, textural and palaeohydraulic analyses as well as luminescence dating were performed so as to achieve the aim of study. Sedimentary successions were identified as a record of point bar cycles. The fluvial environment probably functioned during the latest Saalian, shortly after the retreat of the Scandinavian Ice Sheet. Discharge outflow was directed to the northwest. The river used the older fluvioglacial valley and probably was directly connected to the Eem Sea. Good preservation and strong aggradation of point-bar cycles were related to a rapid relative base level rise. The meandering river sediments recognised showed responses to climate and sea level changes as illustrated by stratigraphical, morphological and sedimentological features of the strata described. The present study also revealed several insights into proper interpretation of meandering fluvial successions, in which the most important were: specific lithofacies assemblage of GSt (St, Sp) → Sl → SFrc → Fm (SFr) and related architectural elements: channel/sandy bedforms CH/SB → lateral accretion deposits LA → floodplain fines with crevasse splays FF (CS); upward-fining grain size and decreasing content of denser heavy minerals; estimated low-energy flow regime with a mean depth of 1.6–3.3 m, a Froude number of 0.2–0.4 and a sinuosity of 1.5.
Źródło:
Geologos; 2016, 22, 1; 1-14
1426-8981
2080-6574
Pojawia się w:
Geologos
Dostawca treści:
Biblioteka Nauki
Artykuł
    Wyświetlanie 1-7 z 7

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