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Wyświetlanie 1-2 z 2
Tytuł:
Formation of calcite by chemolithoautotrophic bacteria – a new hypothesis, based on microcrystalline cave pisoids
Autorzy:
Gradziński, M.
Chmiel, M.J.
Motyka, J.
Powiązania:
https://bibliotekanauki.pl/articles/191736.pdf
Data publikacji:
2012
Wydawca:
Polskie Towarzystwo Geologiczne
Tematy:
microbial carbonates
biomineralization
biofilm
speleothems
Carpathians
Opis:
A new mechanism, stimulating the precipitation of calcite, is postulated. The supersaturation with respect to carbonate minerals is changed, as a result of CO2consumption by chemolithoautotrophic, hydrogen-oxidizing bacteria. This mechanism controls the growth of atypical, microcrystalline cave pisoids in Perlová Cave, in Slovakia. The pisoids grow under calm conditions in rimstone pools, where they are bathed continuously in stagnant water. The water is supersaturated, with respect to calcite and aragonite. The bacteria inhabit the outer parts of the pisoids, covered by biofilms. The biofilm influences the supply of the Ca2+ ion, slows down the precipitation rate, and favors calcite precipitation over that of aragonite. The calcite initially precipitates as bacterial replicas, which further act as seeds for the growing calcite crystals. This process leads to the obliteration of the primary, bacterial fabrics. Since hydrogen-oxidizing bacteria occur in a wide spectrum of natural habitats, the mechanism of calcification, postulated above, also may operate in other environments.
Źródło:
Annales Societatis Geologorum Poloniae; 2012, 82, 4; 361--369
0208-9068
Pojawia się w:
Annales Societatis Geologorum Poloniae
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Siliciclastic micro- stromatolites in a sandstone cave: role of trapping and binding of detrital particles in formation of cave deposits
Autorzy:
Gradziński, M.
Chmiel, M. J.
Lewandowska, A.
Michalska-Kasperkiewicz, B.
Powiązania:
https://bibliotekanauki.pl/articles/191880.pdf
Data publikacji:
2010
Wydawca:
Polskie Towarzystwo Geologiczne
Tematy:
bacteria
Actinomycetes
biofilm
speleothems
Outer Carpathians
Opis:
The article deals with finely laminated microstromatolites composed of detrital siliciclastic particles, mainly quartz, feldspars and clay minerals, lining the walls of W Sopotni Wielkiej Cave (Polish Outer Carpa- thians). Newly precipitated mineral phases do not contribute to their growth. The microstromatolites cover vertical and overhanging walls of the cave. They form subhorizontal ripples and tongue-shaped stepped microterracettes. The stromatolites are constructed by bacteria and Actinomycetes. Seven morphotypes of micro-organisms have been distinguished. Trapping and binding of detrital particles result in the microstromatolite growth. The growth is influenced by the relatively close distance to the soil cover which provides detrital mineral particles and by the presence of gravitationally widened fissures which guide the water transporting mineral particles down to the cave. The particles are transported only during wet periods. The episodic supply of the particles results in visible lamination of microstromatolites. The microterracettes form in zones of increased water-flow. The lack of auto- chthonous components most probably reflects too low saturation of water to precipitate any minerals.
Źródło:
Annales Societatis Geologorum Poloniae; 2010, 80, No 3; 303-314
0208-9068
Pojawia się w:
Annales Societatis Geologorum Poloniae
Dostawca treści:
Biblioteka Nauki
Artykuł
    Wyświetlanie 1-2 z 2

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