Role of Biological Production in Pleistocene Atmospheric Carbon DioxideVariations and the Nitrogen Isotope Dynamics of the Southern Ocean

摘要

This dissertation contributes to the search for a cause of glacial/interglacialvariations in atmospheric carbon dioxide. The hypotheses addressed involve changes in low and high-latitude biological export production. A modelling exercise demonstrates that the paleoceanographic record of calcite preservation places constraints on hypothesized changes in low latitude biological production. The model results indicate that large, production-driven changes in the depth of the calcite saturation horizon during the last ice age would have caused a similar deepening of the calcite lysocline, even when the effect of sediment respiration-driven dissolution is considered. Such a large glacial lysocline deepening is not evident on an ocean-average basis. The results indicate very few mechanisms by which low latitude production could have driven Pleisotocene carbon dioxide variations, generally arguing against a low latitude cause for these variations.