Occurrence of Fatty Acids and Aliphatic Hydrocarbons in a 3.4 Billion-year-old Sediment

Abstract

THE existence and composition of organic compounds of possible biological origin in Pre-Cambrian rocks provide clues for the understanding of biological evolution and the origin of life. It is known that, after a sufficient length of time, all organic material in sediments tends to be reduced either to aromatic condensates resembling graphite or to aliphatic hydrocarbons. Elevated temperatures accelerate this process. Most biological compounds have low thermal stability, so that they will not be preserved through geological time. Some of the biogenic compounds, for example, porphyrins, amino-acids, fatty acids, ethers and ketones, are somewhat more stable, however, and diagenesis occurs slowly enough for some of the original material to be preserved. Porphyrins^1,2 and amino-acids³ have been investigated by others and, recently, fatty acids in ancient sediments have been reported by Van Hoeven et al.⁴.