BIOMARKER ASSEMBLAGE OF SOME MIOCENE-AGED BULGARIAN LIGNITE LITHOTYPES

Two homogeneous (humovitrain and xylain) and one heterogeneous (humocl arain) lithotype macerals, separated from a lignite, were subjected to mild reductive treatment by NaH. The extensive chromatographic separa tion of the decalin-soluble fraction revealed some structural peculiar ities. A strong predominance of alpha-phyllocladane was characteristic for all macerals. Series of n-, iso-, and anteiso-alkanes, regular is oprenoids, alkylbenzenes and 1-methyl-4-n-alkylcyclohexanes were ident ified by mass spectrometry. An angiosperm source input was represented by friedelane, lupane and seco-hopane structures. Products of des-A a nd des-E-ring cleavages and C-10 demethylation were registered by mass spectrometry. The main difference was in the hopane distribution patt ern. A strong prevalence of extended beta beta-hopanes was found in th e humoclarain sample. The mass spectral data revealed the existence of a basic difference in hopane precursors-diploptene or diplopterol for the homogeneous lithotypes and bacteriohopanetetrol for the heterogen eous lithotype. (C) 1996 Elsevier Science Ltd.