DISTRIBUTION AND ORIGIN OF CYCLOALKANE AND MONOCYCLICAROMATIC IN SEEP-CARBONATES FROM LOWER SLOPES OF GULF OF MEXICO

Reported in this paper are the composition and distribution of alkyl cyclopentanes, alkyl cyclohexanes, linear alkylbenzenes and phenylalkanes in the seep carbonate from AC 645 (Sample AC-E) at the lower slope of Gulf of Mexico, where the water depth is 2 200 m. The distribution of alkyl cyclopentanes and alkyl cyclohexanes is similar to normal alkanes, which are dominated by low molecular weight compounds and maximized at C₁₄,C₁₅, respectively, suggesting that the alkyl cyclopentanes and alkyl cyclohexanes are mainly originated from bacteria and phytoplankton. The carbon number of alkylbenzenes are C₁₃-C₂₃, obviously dominated by even-numbered carbon and maximized at C₁₆, which are probably originated from halophilic bacteria or bacterium or sulfate-reducing bacteria in seep site, and the three group phenylalkanes are likely originated from blue green microalgae and planktonic organisms.