Molecular palaeontology of marine sediments

Abstract

This reports summarises the scientific achievements of the PIONIER project entitled "Molecular palaeontology of marine sediments", which was funded through a grant of almost two million Dutch guilders by the Netherlands Organisation for Scientific Research (NWO). The project was performed both at the Netherlands Institute for Sea Research and Utrecht University and lasted somewhat more than 5 years (1993-1998). The research in this project focussed on the application of new methods to obtain additional information from molecular fossils (biomarkers) to better reconstruct marine depositional conditions through geological time. Besides the carbon skeleton, biochemicals are also characterised by their functional groups and stable carbon isotopic composition. The PIONIER research has revealed that these two latter types of information, in addition to the classical carbon skeleton type of information, can also become preserved in their sedimentary derivatives, enabling a much more detailed reconstruction of palaeoenvironments. Decoding of this information is, however, complicated by a range of processes, from the biosynthesis of biochemicals to diagenetic and catagenetic reactions taking place in sediment. Detailed knowledge on such processes was obtained. The research performed in this project has culminated in over hundred scientific papers; their contents is summarised in this report. Various groups of specific biomarkers are discussed first. Some of these have been identified for the first time, in other cases their application in reconstruction of palaeoenvironments has been significantly improved. Thereafter, a number of important processes in the context of the present study; isotopic controls on the stable carbon isotopic compositions of biomarkers, natural sulfurisation of organic matter, kerogen formation, postdepositional oxidation, and effects of dia- and catagenesis upon sulfur sequestration of biolipids, are summarised. Finally, results from biogeochemical investigations of organic matter-rich sediments from specific depositional settings using the novel analytical approaches are outlined, which in some cases provide a completely new perspective on the conditions of their formation.