IODP Expedition 302, Arctic Coring Expedition (ACEX): A First Look at the Cenozoic Paleoceanography of the Central Arctic Ocean

Introduction The behavior and inf luence of the A rct ic Oceanthroughout the course of the global Cenozoic climateevolution have been virtually unknown. Only the uppermostfew meters of the Arctic’s sediment record, representingHolocene and late Pleistocene times, have been retrievedfrom ridges through a limited number of short piston,gravity, and box cores. Even less of the thick sedimentsequences, ~6 km in the Canada Basin and ~3 km in theNansen Basin(Grantz et al., 1990; Jokat et al., 1995), restingon the Arctic Ocean’s abyssal plains, have been cored.Prior to the Arctic Coring Expedition (ACEX), informationon Neogene or Paleogene conditions in the central Arcticwas limited to a 1.6-m interval in a 3.6-m-long T-3 gravitycore raised from the Alpha Ridge (Clark, 1974), providingthe sole evidence for marine conditions no older than themiddle Eocene in the central Arctic (Bukry, 1984)