Paleoceanography: Geochemical tracers of past Oceans

Group GSI.IR
Location International Geological Congress,oslo 2008
Author Delaney, Margaret; Scher, Howie; Chun, Cecily
Holding Date 03 September 2008

The interplay of oceanic biogeochemical cycles with climatic events and trends, tectonic drivers, and weathering and sedimentary burial fluxes affects global carbon cycling. Paleoceanography seeks to reconstruct past ocean conditions over all timescales and at all temporal resolutions, and understanding carbon cycle forcing and responsein the ocean is critical to defining the likely outcomes of anthropogenically forced changes. We rely on records of Earth and ocean history buried in marine sediments to reconstruct the past, and my focus has been especially on geochemical trends and events of the past 65 myr of the Cenozoic. We use geochemical tracers of ocean history to investigate oceanic sediment paleo-redox changes, nutrient cycles changes, and weathering and circulation changes. Deciphering the history encoded in the marine sedimentary record has benefited enormously from the international scientific ocean drilling programs (the Deep Sea Drilling Project [DSDP, 1968-1983], the Ocean Drilling Program [ODP, 1985-2003], and the Integrated Ocean Drilling Program [IODP, 2003-]). Using examples from specific climatic events (e.g., the Eocene-Oligocene bounday, the Paleocene-Eocene Thermal Maximum), specific regions (e.g., the Southern Ocean), I will discuss the applications of phosphorus geochemistry and burial, redox-sensitive metals, and neodymium isotopes to demonstrate the challenges and rewards of using geochemical tracers