PETROLOGICAL AND ORGANIC GEOCHEMICAL CHARACTERISTICS OF LIGNITES FROM THE CZECH REPUBLIC

10th International Multidisciplinary Scientific GeoConference - SGEM2010, www.sgem.org, SGEM2010 Conference Proceedings/ ISBN 10: 954-91818-1-2, June 20-26, 2010, Vol. 1, 129-136 pp

ABSTRACT

Organic matter of lignites from five Tertiary deposits in the Czech Republic was studied
and the general goal was to characterize a series of different coal lithotypes in relation
to depositional environment from the viewpoint of organic petrology and geochemistry.
Coal samples were chosen to cover various lithotypes: xylite rich coals, matrix coals,
liptobioliths, and sapropelic coals. The samples differ in ash, sulphur, carbon, hydrogen,
oxygen and volatile matter contents, and calorific values. Xylite rich and matrix coals
are characterized by higher ulminite, densinite and lower textinite and resinite contents.
Sapropelic coal from the North Bohemian and Žitava basins are formed by large amount
of huminite macerals and high portion of liptodetrinite, sporinite and alginite. Different
composition was found in clayey sapropelic coal from the Uhelná relic that contains
more liptodetrinite, alginite and sporinite, and lower content of huminite macerals.
Fundamental essential difference between sapropelic coal and liptobioliths consists in
high contents of liptodetrinite, bituminite, resinite, inertinite, and lower contents of clay
minerals in liptobioliths. Representation of n-alkanes according to coal lithotypes was
interesting because identical trends in distribution were found. Long n-alkanes were
dominant in liptobioliths and sapropelic coals. The middle-chain n-alkanes prevailed in
xylite rich coals. The short-chain n-alkanes were intensive in matrix coals. The fossil
pattern of biomarkers is indicative of their derivation from natural products:
sesquiterpenoids of cadalene group and the diterpenoid α-phyllocladane were the most
abundant compounds found in lignite samples.

Keywords: organic geochemistry, lignite, biomarkers, terpenoids