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Wyświetlanie 1-3 z 3
Tytuł:
Middle Weichselian Pleniglacial sedimentation in the Krasówka river palaeovalley, central Poland
Autorzy:
Wachecka-Kotkowska, L.
Krzyszkowski, D.
Klaczak, K.
Król, E.
Powiązania:
https://bibliotekanauki.pl/articles/191210.pdf
Data publikacji:
2014
Wydawca:
Polskie Towarzystwo Geologiczne
Tematy:
alluvial deposits
MIS 3
sedimentary petrology
AMS
palynology
radiocarbon dates
Bełchatów mine
Opis:
This study from the Szczerców field of the Bełchatów open-cast mining complex, central Poland, reveals the local geomorphic and stratigraphic history of the Krasówka river palaeovalley – a major western tributary of the river Widawka. The data are from the western flank of the N-trending palaeovalley and the study combines detailed lithofacies analysis of outcrop sections, sediment petrology, AMS measurements and palynological evidence. Radiocarbon dates are of crucial importance for the reconstruction of the palaeovalley history. The study contributes to a better understanding of the response of the Central European river systems to the Vistulian Pleniglacial conditions. The Vistulian Pleniglacial sedimentation in the study area commenced with the accumulation of the latest Eemian to earliest Weichselian (≥45 ka) deposits by sheetwash processes in a local karstic topographic depression. The Krasówka river then formed to the east and shifted farther eastwards, but later approached twice the study area with a net aggradation prior to 43 ka BP – flooding it with overbank deposits. The river subsequently incised by nearly 20 m around 40 ka BP and began to fill in its valley by aggradation around 35 ka BP, while migrating eastwards and markedly decreasing its flooding capacity from 33 to 24 ka BP. The fluvial system was rejuvenated around 21 ka BP, with some initial erosion, and kept filling its valley by aggradation while flooding the valley flank. The river after filling its valley continued to aggrade, but gradually ran out of vertical accommodation and migrated westwards. The fluvial activity at this stage was increasingly accompanied by aeolian sedimentation. Once the Mid-Weichselian Pleniglacial came to an end around 14.5 ka BP, the Krasówka river had re-incised by nearly 5 m and assumed its present-day altitude in response to the post-glacial regional isostatic rebound of crustal basement.
Źródło:
Annales Societatis Geologorum Poloniae; 2014, 84, 4; 323-340
0208-9068
Pojawia się w:
Annales Societatis Geologorum Poloniae
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Grain-size characteristics of deposits derived from different glacigenic environments of the Schirmacher Oasis, East Antarctica
Autorzy:
Srivastava, Ashok K.
Ingle, Pravin S.
Lunge, Harihar S.
Khare, Neloy
Powiązania:
https://bibliotekanauki.pl/articles/94496.pdf
Data publikacji:
2012
Wydawca:
Uniwersytet im. Adama Mickiewicza w Poznaniu
Tematy:
sedimentary petrology
granulometry
glacial sediments
Schirmacher Oasis
Antarctica
petrologia osadowa
granulometria
osad lodowcowy
Antarktyka
Opis:
Sediment samples have been collected from the Schirmacher Oasis and adjoining area in East Antarctica; these areas consist of polar ice, ice-free area, lakes and the coastal shelf area. The 37 samples have been analysed for their grain-size parameters and statistical relationships. The oasis is characterised by ongoing glacial processes, including deposition and erosion of the sediments by ice, meltwater and winds, thus influencing the sediments in various ways. Basic statistical grain-size parameters like graphic mean, standard deviation, skewness and kurtosis have been calculated for the four units. The sediments of all areas are almost all poorly to very poorly sorted, fine-skewed to near-symmetrical and platykurtic to leptokurtic in nature. Bivariate plots between the grain-size parameters have been interpreted. They do, apart from a few exceptions, not show any trend suggesting relationships between the sediments of the four landscape types. Both t- and F-tests have been applied on the samples, and the phi values and grain-size parameters have been analysed; these show that the group variances of the samples are not significant, but that the phi-values are significant.
Źródło:
Geologos; 2012, 18, 4; 251-266
1426-8981
2080-6574
Pojawia się w:
Geologos
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
The Pliocene Paludina Lake of Pannonian Basin : new evidence from northern Serbia
Autorzy:
Rundić, L.
Vasić, N.
Životić, D.
Bechtel, A.
Knežević, S.,
Cvetkov, V.
Powiązania:
https://bibliotekanauki.pl/articles/191318.pdf
Data publikacji:
2016
Wydawca:
Polskie Towarzystwo Geologiczne
Tematy:
flora
freshwater fauna
lacustrine palaeoenvironment
lignite petrology
organic geochemistry
sedimentary facies
Opis:
This study from the Sremski Karlovci clay pit in northern Serbia sheds new light on the physicochemical conditions, ecology and evolution of the Paludina Lake – the Pliocene successor of the late Miocene giant Lake Pannon hosted by the Pannonian Basin. The multidisciplinary study combines sedimentology, sequence stratigraphy, biostratigraphy, palaeontology, palaeobotany, coal petrology, organic geochemistry and magnetic mineralogy. The sedimentary succession studied represents the lake margin at the foot of the Fruška Gora ridge. Sedimentary facies reveal minor and major lake-level changes, including a forced regression with fluvial valley incision in the succession middle part and the ultimate emergence and covering of the lake floor by Pleistocene loess. Mollusc and ostracod fauna indicates an oligohaline shallow cool-water environment, no deeper than 5–6 m, with an active inflow of spring water. The lake local depth during transgression maxima did not exceed 20 m. Palynological and geochemical analyses indicate a rich and diversified assemblage of gymnosperm plants with a contribution of angiosperms, weeds and microbial biomass in the peat-forming suboxic to oxic coastal swamp environment. Maceral analysis of organic matter shows a prevalence of huminite, accompanied richly by inertinite in lignite and by liptinite in clay. The Pleistocene shift to terrestrial semiarid environment resulted in oxidizing groundwater conditions, with the reddening of sediments around a fluctuating groundwater table and the diagenetic transformation of bacteria-derived greigite into magnetite. In regional stratigraphy, the occurrence of Viviparus neumayri Brusina in the lower half of the succession indicates the Lower Paludina Beds of Dacian Stage (early Zanclean age). Other gastropods and certain ostracodes indicate transition to the Middle Paludina Beds of lower Romanian Stage (late Zanclean–early Piacenzian). The upper half of the succession lacks age-diagnostic fossils and is considered to represent Middle Paludina Beds with a possible relic of Upper Paludina Beds at the top.
Źródło:
Annales Societatis Geologorum Poloniae; 2016, 86, 2; 185-209
0208-9068
Pojawia się w:
Annales Societatis Geologorum Poloniae
Dostawca treści:
Biblioteka Nauki
Artykuł
    Wyświetlanie 1-3 z 3

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