MOLECULAR INDICATORS FOR TAXODIUM DUBIUM AS COAL PROGENITOR OF "CHUKUROVO" LIGNITE, BULGARIA
(EN)
Stefanova, M.
The coal sediment under study was of Miocene/Pliocene geological age. The petrological data pointed to Tortonian/Sarmatian age, while the paleobotanical ones - to Middle Miocene. It was documented that "Chukurovo" basin was determined by coal fades indices as limnic ombrotrophic forester swamp. Fossilized trees predominated in "Chukurovo" lignites. Well preserved wood tissue of stems and twigs impregnated by clays and enriched in organic matter were macroscopically observed. Four types of phytocenosis - aquatic, swamp, flood plain, forests, i.e. mesophilous and mesohygrophilous were proposed. The composition of the last one confirmed the predominance of evergreen laurel and laurel-oaks communities during the Miocene. In the present investigation tools of organic geochemistry were applied. Extractable matter from Taxodium dubium (Sternb.) Heer was studied by a sequence of extraction, separation and chromatographic identifications. The molecular data confirmed botanical assignment of the macrofossil to conifer family Taxodiaceae. A lot of identified geolipids, i.e. alkanes, alcohols, fatty acids, and steranes/triterpanes were without chemosystematic value as ubiquitous in plant kingdom. Ferruginol, sugiol, totarol and products of their diagenetic transformations were identified as the dominant biomarkers. Ferruginol and its homologues were the most abundant phenols in Taxodium dubium (Sternb.) Heer. The biomarker composition of extractable matter strongly suggested that species of Cupressaceae /Taxodiaceae contributed in major amounts to "Chukurovo" paleoplant swamp.
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