Organic geochemistry of the marl slate and other organic rich sediments

Abstract

Several samples from the Permian Marl Slate of County Durham and their lateral equivalents in Nottinghamshire and beneath the North Sea have been analysed quantitatively and qualitatively for their geolipid content. Results have shown that a series of normal paraffins ranging in carbon number from C₁₂ to C₃₂and a series of isoprenoid hydrocarbons C₁₅ ' C₁₆ ' c₁₈ ' C₁₉ and C₂₀ are present. Metalloporphyrins were shown to be present in all of these samples other than those from the North Sea area. A homologous series of etio and phyllo type porphyrins chelated with nickel and vanadium were identified in a concentration of 37 parts per million per unit weight of sample. The presence of fatty acids in some of the samples was shown to be very low with respect for other shales, e.g. Colorado Green River Shale. A series of normal and isoprenoid fatty acids were identified and shown to be similar to the distribution of alkanes. Hydrogenolysis experiments of Marl Slate kerogen have shown that mild thermal treatment in the presence of hydrogen and catalyst generates hydrocarbons with a distribution similar to that obtained from the soluble lipid fraction of Marl Slate. The Miocene Bovey Tracey Lignite of Devon has been analysed and shown to contain a homologous series of normal paraffins and alkanoic fatty acids. Isoprenoid cyclic hydrocarbons are present and triterpenoids previously identified in lignites by other workers have been identified and confirmed.