2-methylretene in sedimentary material: a new higher plant biomarker

2-Methylretene has been synthesised, characterised and identified in sedime ntary material from a range of locations, source types and ages. 2-Methylre tene was observed only in samples of Permian to Tertiary age and can be ass ociated with specific higher plant precursors that also yield retene. Labor atory dehydrogenation of simonellite yielded 2-methylretene as the major pr oduct. Based on this we suggest that 2-methylretene forms from the aromatis ation of diterpenoid type natural products with the abietane and phylloclad ane skeletons, similar to those that form simonellite and suggest it can be used as a biomarker for higher plant input. (C) 2001 Elsevier Science Ltd. All rights reserved.