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Wyszukujesz frazę "Holocene sediment" wg kryterium: Temat


Wyświetlanie 1-3 z 3
Tytuł:
Numeric de-compaction of Holocene sediments
Autorzy:
Schmedemann, N.
Schafmeister, M. T.
Hoffmann, G.
Powiązania:
https://bibliotekanauki.pl/articles/1204990.pdf
Data publikacji:
2008
Wydawca:
Państwowy Instytut Geologiczny – Państwowy Instytut Badawczy
Tematy:
peat
mud
sediment
compaction
de-compaction,
modelling
Holocene
Opis:
Sea-level development is often determined by the interpretation of Holocene sediments. To do this, sea-level curves are fixed by dating organic enriched sediments and measuring their depositional heights. Organic enriched sediments like organic mud or peat which are usually well dateable are also susceptible to compaction. To correct the layers for initial sediment thickness and consequently the depositional heights for dated sediments, it is necessary to de-compact the sediment sequence for the dated point. By this the correct paleo-surface at the time of deposition can be reconstructed. The software "DeLos" (Dekompaktion von Lockersedimenten) is written to perform the time consuming calculations in a fast way. The software assumes that sediments are composed of an incompactable solid part and compactable pore space. DeLos shows that the surface displacement could easily reach magnitudes of 50% within high compactable sediments. Especially such layers with large thicknesses of several meters are often used to get vertical profiles for time-depth correlation (Brown, 1975). Due to compaction processes the dated samples are remarkably displaced.
Źródło:
Polish Geological Institute Special Papers; 2008, 23; 87-94
1507-9791
Pojawia się w:
Polish Geological Institute Special Papers
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Sediment discharge and storage over the last deglacial highstand period on the central Vietnam shelf off Nha Trang
Autorzy:
Dung, Bui Viet
Stattegger, Karl
Kieu, Nguyen Van
Thanh, Nguyen Trung
Thong, Bui Xuan
Vu, Pham Nguyen Ha
Man, Ha Quang
Trang, Pham Hong
Powiązania:
https://bibliotekanauki.pl/articles/2058662.pdf
Data publikacji:
2019
Wydawca:
Państwowy Instytut Geologiczny – Państwowy Instytut Badawczy
Tematy:
sediment budget
Nha Trang shelf
central Vietnam
Holocene highstand
sequence stratigraphy
Opis:
A sediment budget for the central Vietnam shelf off Nha Trang over the last deglacial Holocene highstand period has been investigated on the basis of shallow seismic and sediment core data and empirical equations. The annual suspended sediment discharge to the Nha Trang shelf ranges from: 4.3 to 5.4 Mt/year. Estimates based on published empirical equations suggest that the sediment discharge by three main local mountainous rivers (the Cai, Dinh and Van Phong rivers) that enter the Nha Trang shelf ranges between 1.7 and 4 Mt/year, which implies that the local rivers discharge approximately 75% of the total annual sediment input to the shelf. The annual sediment supply of the Cai River is approximately 2 and 6 times higher than that of the Dinh and Van Phong rivers, respectively. The highstand sediment depocentre of the Nha Trang shelf is mostly attached to the local river outflows, indicating their importance as the principal sediment supply sources to the shelf. Additional sources of sediment supply to the Nha Trang shelf can probably be related to along-shore transport from the nearby shelves. Calculations based on seismic and sediment core data indicate that the net sediment volume storage on the Nha Trang shelf is approximately 2.15 Mt/year. Approximately 50% of the total sediment yield supplied to the shelf is probably transported along-shore to the south. The sediment budget model for highstand deposits on the Nha Trang shelf is typical for a small mountainous river basin, which is significantly different from that of the large river delta systems in Vietnam such as the Mekong and Red rivers where 90% of the river sediments are captured on the delta plain/subaqueous part and only 10% of the river sediments are transported to the nearby shelf. In contrast, most of the sediments supplied by small mountainous rivers off Nha Trang are transported to the mid-shelf, forming a shore-parallel mud depocentre.
Źródło:
Geological Quarterly; 2019, 63, 2; 395--406
1641-7291
Pojawia się w:
Geological Quarterly
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Mikrokonkrecje syderytowe w holoceńskich osadach ujścia rzeki Gwadiana w Portugalii : raport wstępny
Micro-scale sideritic concretions in Holocene sediments in the Guadiana estuary, Portugal : a preliminary report
Autorzy:
Wilamowski, A.
Boski, T.
Moura, D.
Powiązania:
https://bibliotekanauki.pl/articles/2075017.pdf
Data publikacji:
2013
Wydawca:
Państwowy Instytut Geologiczny – Państwowy Instytut Badawczy
Tematy:
siderite
concretions
estuarine sediment
Guadiana River
Holocene
syderyt
konkrecje
sedymentacja osadów
rzeka Gwadiana
holocen
Opis:
The authors described micro-scale carbonate concretions occurring at a depth of about 41 m within Holocene sandy sediments filling the Guadiana River paleovalley, representing the transitional fluvial- -estuarine facies. Despite their minute sizes, the micro-concretions show a complex internal structure. Regular distribution of Mg, Mn and Ca can be assigned to a chemical zoning, pointing to precipitation under varying chemical conditions. Based on morphological and chemical peculiarities, four types of concretions can be distinguished. Detrital Fe-Mg-carbonates form nuclei. At first, Mn-rich carbonate precipitated as a coating, which is coherent with the sequence of precipitation of carbonates associated with bacteria-mediated oxidation of organic matter. Subsequently, the main bodies of concretions precipitated as Fe-carbonate (siderite). The last precipitation episode is marked by enrichment in Ca. The XRD patterns show the presence of a mixture of discrete carbonate phases.
Źródło:
Przegląd Geologiczny; 2013, 61, 10; 568--575
0033-2151
Pojawia się w:
Przegląd Geologiczny
Dostawca treści:
Biblioteka Nauki
Artykuł
    Wyświetlanie 1-3 z 3

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