Paleoproductivity and Oceanic Nutrient Budgets

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This project will address two questions concerning the long-term relationships between ocean production and nutrient cycles. (1) How do changes in export production affect nutrient burial? (2) What are the relative roles of nutrient supply from continental weathering and nutrient recycling from the sediments? Two Cenozoic time intervals will be studied: 38-20 Ma, incorporating periods of rapid variation in 13 C and climate, to determine the effect of varying production upon organic burial and CO2 drawdown, and 64-50 Ma, incorporating a sustained maximum in 13 C during a climatic warm phase, to determine how large-scale changes in the C cycle are related to production and nutrient burial. Analyses will include barite (as a tracer of production), reactive P (as tracer of nutrient burial), 13 C in bulk calcite, and %CaCO3, opal and organic C, using ODP cores from a variety of oceanic settings.