Developing an early to middle Miocene benthic foraminiferal isotope chronostratigraphy across the Pacific "paleoequator transect" (IODP PEAT Expedition 320/321)

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We propose to develop an early to middle Miocene (20-13 Ma) astronomically-calibrated benthic isotope chronostratigraphy in a „mega-splice“ constructed from sedimentary successions drilled across the Pacific equatorial age transect (PEAT) during IODP Expedition 320/321. We will especially focus on the enigmatic 16-20 Ma interval, which is not yet firmly anchored within the geological timescale and still requires major clarification. The PEAT Expedition 320/321 provided for the first time the opportunity to recover this time slice in one of the most climate sensitive regions of the world, where calcareous sediments have been preserved best. Our work will contribute to improving the Cenozoic timescale, and will supply an essential chronological framework for future studies of Miocene climate, paleoceanography and evolutionary patterns. Our stable isotope records will also provide important information about ice volume fluctuations, Pacific deep-water characteristics and re-organizations in deep-water circulation associated with major climatic events (including the Miocene Climatic Optimum and Mi-1-3 glaciations). Ultimately, we will integrate our research with other postcruise studies to comprehensively explore the relationships between equatorial Pacific paleoproductivity, carbon isotope signals and the carbon cycle.