Did change of deep water source amplify or diminish the climate fluctuation?: oceanic event stratigraphy of sulfur isotopes

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Initial purpose of this project is to capture a rapid switch of oceanic deep water sources and to understand how the climate responds to it. After introduction of a mass spectrometer, preparation and analytical techniques for sulfur isotope analysis of carbonate associated sulfate were developed. However, we found that sulfur isotope data do not provide good data for the discussion of our purpose. We abandoned sulfur isotope method and switched our methods to that based on high resolution carbon isotope stratigraphy and theoretical analyses. Then we could estimated time scale of deep water circulation during mid-Cretaceous. A model for evaluating sensitivity of the oceanic environment against CO2 increase in the atmosphere was constructed.