Organic Geochemical Approach to Problems of Glacial-Interglacial Climatic Variability

摘要

The combined analyses of organic biomarker compounds, the concentration and carbon isotopic composition (delta (13)C) of sedimentary organic carbon (C(org)), and N/C ratios formed a basis from which to address problems of glacial-interglacial climatic variability in a Late Quaternary 208.7 m hydraulic piston core (Deep Sea Drilling Project Core 619) from the Pigmy Basin in the northern Gulf of Mexico. A study of selected organic biomarker compounds which could serve as tracers of terrigenous and marine sedimentary organic matter sources was performed by comparison with contemporaneous sedimentary organic carbon isotopic composition (delta (13)C-(org)). Organic carbon-normalized concentrations of total long chain (C37-C39) unsaturated alkenones (from Prymnesiophyte phytoplankton) and individual C27-C29 desmethyl sterols were determined to be useful proportional indicators of preserved marine and terrigenous organic carbon, respectively. The sedimentary records of both terrigenous and marine organic carbon-normalized biomarker compound concentrations appear to be systematically altered by the remineralization of sedimentary organic carbon, as indicated by a simple, first-order organic carbon decay model. (Copyright (c) John P. Jasper 1988.)