Origin of perylene in ancient sediments and its geological significance

The distributions of polycyclic aromatic hydrocarbons (PAHs) in sediments o f three Upper Triassic to Middle Jurassic sedimentary sequences from the No rthern Carnarvon Basin, Australia have been investigated. Perylene was foun d to be a major PAH component in the top Lower to base Middle Jurassic sedi ments that are immature or at low maturity. Its depth/ age profiles are not related to the combustion-derived PAHs that have been believed to be produ ced during ancient vegetation fires before deposition. This suggests a diag enetic origin for perylene. The concentration of perylene in the sediments is proportional to the amount of terrestrial input, decreasing with distanc e from the source of land sediments. Its carbon isotope composition is slig htly heavier than higher-plant derived PAHs, but still in the range of the terrestrially sourced PAHs including higher-plant PAHs and combustion-deriv ed PAHs as suggested previously. Fungi are proposed to be the major precurs or carriers for perylene in sediments based on the facts that (1) peryleneq uinone structures have been previously suggested to be the natural precurso rs for perylene; (2) perylenequinone pigments exist in many fungal bodies; (3) fungi have played an important role during geological processes. (C) 20 00 Published by Elsevier Science Ltd. All rights reserved.