This project addresses important topics concerning ocean productivity in the equatorial Pacific (EP), atmospheric paleo-CO2 and the global carbon cycle over the past 26 Ma period as inferred from paleontological and geochemical analyses of sediment cores collected from the IODP PEAT expedition, leg 320. This expedition was highly successful at retrieving the first complete Cenozoic record from the equator. Although a highly productive region, the high nutrient load of the EP makes it an inefficient ecosystem, thus making it susceptible to rapid changes in cycling rates and serving an important role in ocean biogeochemical cycles. Major changes in biogenic sedimentation in the EP throughout the Cenozoic is believed to reflect past changes in this cycling and in productivity. Sedimentary diatom assemblages will be analyzed from cores of leg 320 as indicators of productivity, bio-Ba and bio-Si will be used as indicators of export production, and organic carbon and CaCO3 measurements will be made to understand the past changes in carbon cycling. This comprehensive multi-proxy approach and micropaleontological analyses will increase our understanding of paleoproductivity, carbon export and burial, and biogeochemical cycling in the equatorial regions during the middle to late Miocene.
Broader impacts: Atmospheric CO2 levels are strongly regulated by ocean productivity. Understanding past changes in ocean productivity during warm earth conditions from analysis of the sedimentary record provides insights into natural variations of paleo-atmospheric CO2 levels and the biogeochemical influences of this. This study will provide fundamental information for better understanding global climate. The project provides financial assistance for undergraduate students and will support and train a graduate student. The project takes good advantage of a large investment previously made in an IODP expedition and strengthens international collaborations within the IODP community.
