Experimental diagenetic study of a modern lipid-rich sediment

Abstract

Holocene organic-rich sediments were subjected to a series of laboratory experiments in order to evaluate the relative importance of temperature, pressure, the presence/absence of soluble lipids and nascent atmospheric conditions on generated products. Samples were heated at 80, 160 and 240°C for 50 h and the hexane-, benzene- and chloroform-soluble fractions were determined at the conclusion of each experiment. C 12C 30 aliphatic fatty acids and C 15C 32 n-paraffins were analyzed individually. Maximum n-paraffin yields occurred at the highest temperatures; these paraffins were derived from the insoluble organic material (kerogen) as well as decarboxylation of fatty acids. The odd-C dominance of paraffins from the original sediments disappears as a function of temperature thus laboratory studies parallel observations made by Philippi on natural diagenesis. Fatty acids from both lipid-extracted and unextracted samples retain an even-C dominance at 240°C. At 160°C, fatty acids are released from the kerogen matrix at rates exceeding their degradation. An analysis of variance (ANOVA) was conducted. The ANOVA indicated that, for conditions employed in the study, the only factors which affected variation in components measured at the end of each experiment were: (1) organic matrix (presence/absence of soluble lipids); (2) temperature; and (3) the organic matrix—temperature interaction.