Precambrian organic compounds from the Ketilidian of South-West Greenland. Part III

Abstract

Ketilidian sedimentary rocks nearly 2000 m.y. old and only slightly metamorphosed have been shown to contain fossils and organic compounds. Results of work on organic material from a 1-3 m thick coal-graphite layer from the Foselv Formation in the Sortis Group in Grænseland are presented. Aliphatic (straight chain, branched and cyclic) hydrocarbons are dominant in the extract from two coal-graphite samples weighing about 4 kg and 10 kg respectively. Further investigations of these compounds have revealed many saturated straight-chain hydrocarbons, with the n-C₁₅ alkane, the most abundant among the normal alkanes, ranging from C₁₂ to about C₂₁, and various isoalkanes and anteisoalkanes. Saturated cyclic hydrocarbons like alkyl cyclohexanes, and homologous series of alkyl benzenes and alkyl naphthalenes are also present. A series of monoterpenoid compounds is present. Six of them are fairly well characterized by their mass spectra. Fatty acids and methyl esters of fatty acids are present, notably a homologous series of straight-chain fatty acids. Branched acids are also present in minor amounts. The organic compounds further indicate that this Precambrian coal-graphite layer is the result of biological activity.