COMPARISON OF RESINITE-RELATED AROMATIC BIOMARKER DISTRIBUTIONS IN CRETACEOUS TERTIARY COALS FROM CANADA AND GERMANY

A set of 13 Cretaceous-Tertiary coals from western Canadian coal deposits and two Cretaceous coals from the southern part of the Lower Saxony Basin of Germany have been investigated using microscopical and organic geochemical methods. The coals are in the rank range of lignite to medium volatile bituminous (0.37-1.13% R(r)). Petrographically the coals are characterized by varying proportions in vitrinite, inertinite and liptinite groups. In most of the coals resinite constitutes the major liptinite component. Both of the German Wealden coals are composed exclusively of conifer needles. GC-MS analyses indicate differences in the composition of resin-related molecular biomarkers comparing samples from both deposits. In the Canadian coals of moderate rank (0.4-0.8% R(r)) resin-related naphthalene derivatives are associated with tricyclic aromatic hydrocarbons such as retene, abieta-6,8,11,13-tetraene, simonellite and C5-phenanthrene. Samples higher in rank (about 1.1% R(r)) provide fully aromatized and partly desalkylated phenanthrene homologues. Generation of 1-methylphenanthrene from retene during maturation affects molecular rank parameters like MPR and MPI 1. Additionally, an intra-seam homogenization of resin-derived aromatic hydrocarbon is observed. In comparison the German Wealden coal extracts are dominated by bicyclic aromatic hydrocarbons and they are poor in tricyclic hydrocarbons. Analyses of hand-picked macerals (resinites and cutinites) by thermodesorption coupled to GC-MS indicate the presence of two potential sources for the naphthalene derivatives: C4-tetralin is primarily associated with the resins of Abietites linkii. 1,2,5-Trimethylnaphthalene and 1,2,5,6-tetramethylnaphthalene are probably derived from the fluorinite filling of the conifer needles.