Aromatized arborane/fernane hydrocarbons as biomarkers for cordaites.

Previous palaeobotanical and palynological studies on coals from Euramerican Pennsylvanian ( identical with Late Carboniferous) coal basins indicate a major change in coal-swamp floras, especially at the Westphalian-Stephanian ( approximately Kasimovian-Gzhelian, according to Geological Time Scale 2004) boundary. A flora dominated by arborescent lycophytes was replaced by a vegetation dominated by marattialean tree ferns in various Euramerican coal basins. Earlier combined palynological and organic geochemical studies on Westphalian/Stephanian coals and shales from the Saar-Nahe Basin (Germany) revealed that the distribution of aromatized arborane/fernane hydrocarbons in solvent extracts reflects the increasing importance of seed plants, especially cordaites (extinct group of gymnosperms), conifers and pteridosperms.