One of the most challenging problems in the field of organic geochemistry is the determination of the chemical and physical structure of fossil organic macromolecules -- that is, macromolecules originating from living organisms but no longer contained in them. These 'geopolymers' are often of exceedingly high-molecular weight and so highly cross-linked that they are difficult to work with in the laboratory. Coal, peat, and kerogen are important examples. While technological developments in chemical instrumentation over past three decades have allowed us to penetrate the structures of a great many macromolecules in living organisms (e.g., proteins, nucleic acids), the intractable nature of geopolymers has severely limited extension of the same technology to the study of coal, peat, kerogen, and other high molecular weight geopolymeric substances. In this study, the principal investigators will attempt to make inroads into this problem by studying the fossil organic matter in two sediments: a relatively young marine sediment from the Peru continental margin, and a Miocene shale from the Monterey Formation. To keep this difficult task manageable, their approach will concentrate primarily on just one class of organic constituents that make up the organic matrix in these sediments - lipids. Using a series of chemical degradation and solvent extraction steps (chemolysis), the macromolecular structure will be broken apart and the pieces, especially lipid fragments, will be indentified and quantified. By carrying out the chemolysis in a methodological, stepwise fashion, the investigators hope to be able to draw inferences about the overall polymeric structure, the processes involved in its formative history, and its reactivity.
