Record details

Title
    Geochemistry of Miocene lacustrine sediments from the Sokolov Coal Basin (Czech Republic)
Statement of responsibility
    Bohdan Kříbek, Mojmír Strnad, Zbyněk Boháček, Ivana Sýkorová, Jiří Čejka, Zdeněk Sobalík
Author
    Boháček, Zbyněk
    Čejka, Jiří
    Kříbek, Bohdan, 1946-
    Sobalík, Zdeněk
    Strnad, Mojmír
    Sýkorová, Ivana, 1969-
Language
    anglicky
Source title - serial
    International journal of coal geology
Vol./nr.
    Vol. 37, no. 3-4
Pages
    p. 207-233
Year
    1998
Notes
    3 obr., 10 diagr., 1 fot., 4 tab., 3 s.bibl.
    Zkr. název ser.: Int. J. Coal Geol.
Subject group
    biomarker
    bitumeny
    chemismus hornin
    jíl
    kerogen
    miocén
    sedimentace lakustrinní
    sedimenty bohaté organickým uhlíkem
    sokolovská pánev
    uhelný revír
    uhlík organický
Geographical name
    ČR-Čechy
    Sokolov
Keyword
    Basin
    Coal
    Czech
    Geochemistry
    Lacustrine
    Miocene
    Republic
    Sediments
    Sokolov
Abstract (in english)
   Sediments of the upper part of the Sokolov Formation Brown Coal Basin consist mostly of brown lacustrine clays and claystones enriched in organic matter (2-18% TOC). The lower portion of the stratigraphic profile is formed mostly by kaolinite-illite clays and claystones, while the montmorillonite content increases in the upper portion. The change in the lithology of sediments is caused by the gradual erosion of the weathering crust in the source areas of the clastic material. Inversion of the weathering profile during erosion is manifested geochemically in a decrease in the Al2 O3/Na2 O ratio and an increase in the SiO2/Al2 O3, Na2 O/K2 O and K2 O/TiO2 ratios from the base to the top of the studied part of the Sokolov Formation. The amounts of trace elements (La, Ce, Nb, Zr, Cr, V, Sn) also decrease in the same direction. On the other hand, the amounts of Rb and Sr increase. The organic matter of the upper part of the Sokolov Formation consists primarily of Types I and II kerogen.
   Only near the base of the studied part of the formation, i.e., in the coal stringer, kerogen of Type III prevails. The extremely low degree of thermal maturity permits determination of the source of the organic matter and characterization of its accumulation environment. The organic material in the sediments is predominantly of algae origin. Relatively high amount of pentacyclic triterpanes of the hopane series indicates either the occurrence of cyanobacteria as primary producers or bacterial reworking during sedimentation and diagenesis. Organic matter accumulated under the conditions of a fresh-water lake or lake with slightly elevated salinity, in a dysoxic aqueous environment. The alternation of organic carbon-rich layers with layers low in organic matter is explained in terms of changes in the degree of dysoxia of the aqueous environment and a variation in the intensity of oxidation and mineralization of the organic material
Contributor
    Česká geologická služba
Contributor code
    ČGS (UNM)
Source format
    U
Entered date
    24. 11. 2009
Import date
    8. 8. 2012