Geolipids in the oil shale from Aleksinac (Yugoslavia)

Most of the geolipids so far identified in the oil shale from Aleksinac represent well known /eta/ and ubiquitous constituents of sediments: /eta/-alkanes, aliphatic and cyclic isoprenoid alkanes including steranes, triterpanes and tetraterpanes and aliphatic and aromatic mono- and dicarboxylic acids. Moreover, several classes of compounds were identified which were also known as constituents of some ancient sediments but were not found to be ubiquitous, such as aliphatic isoprenoid ketones C/sub 13/ and C/sub 18/, aliphatic methyl ketones C/sub 13/-C/sub 24/ and the triterpenoid ketone adiantone. However, in the Aleksinac shale bitumen geolipid constituents were identified which had not been found earlier in ancient sediments: a homologous C/sub 7/-C/sub 15/ series of aliphatic /tau/homologous series of 4 members of sigma-lactones, two cyclic ..gamma..-lactones (dihydro- and tetrahydroactinidiolide), as well as a homologous series of methyl esters of fatty acids (C/sub 4/-C/sub 25/). The composition and distribution of identified geolipids suggest: a) that the Aleksinac oil shale is a non-mature sediment (relatively high content of oxygen compounds with unchanged biolipid molecules, high /eta/-alkane CPI values, relatively high amount of unstable stereoisomers in the fraction of steranes and triterpanes) and b) that the organic matter of Aleksinac shale is of mixed origin; themore » following precursors of the organic substance were incorporated in this lacustrine sediment: residues of continental plants, ferns and algae, as well as residues of micro-organisms, most probably of those which took part in early diagenetic changes of sedimented organic matter.« less