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Diagenetic Conditions |
Chemistry Department, Woods Hole Oceanographic Institution, Woods Hole, MA 02543, USA
1 Chevron Oil Field Research Company, PO Box 1627, Richmond, CA 94802, USA
Organic geochemists are currently developing new, molecular-based tools for studying the historical record of coastal upwelling. Several hundred biomarkers, organic compounds with known biological sources, have been identified in sediments underlying the world’s major upwelling systems. Studies completed over the last two decades show that the distribution of many biomarkers in sediments is heavily impacted by the oceanographic and ecological conditions that prevail at the time of sediment deposition. Therefore, these biomakers have the potential to serve as useful palaeoenvironmental indicators. In order to decipher the sedimentary record on the molecular level, a better understanding of early diagenesis, and the coupling between water column biology, chemistry and biomarker distribution in sediments, is needed. Upwelling environments provide excellent sites to conduct such studies. High sediment accumulation rates and good preservation of organic matter in sediments relative to other depositional environments permit high-resolution time-series studies. We summarize here some recent research on early diagenesis, the effect of dysaerobic conditions on biomarker preservation, and the impact of El Nino Southern Oscillation (ENSO) events on the organic geochemical record. We further suggest some specific areas of future research that could substantially enhance our understanding of upwelling environments.
