HR: 14:00h
AN: PP43D-02 INVITED    [Abstracts]
TI: The Cenozoic Arctic Ocean Unveiled through Scientific Ocean Drilling
AU: * Mayer, L
EM: larry@unh.edu
AF: Center for Coastal and Ocean Mapping, University of New Hampshire, 24 Colovos Road, Durham, NH 03824, United States
AU: Moran, K
EM: kate.moran@uri.edu
AF: Graduate School of Oceanography & Dept. of Ocean Engineering, University of Rhode Island, Narragansett Bay Campus, Narragansett, RI 02882, United States
AU: Backman, J
EM: backman@geo.su.se
AF: Department of Geology & Geochemistry, Stockholm University, Stockholm, 10691, Sweden
AB: In late summer 2004, the Integrated Ocean Drilling Program (IODP) conducted one of the most transformational missions in the almost 40 year history of scientific ocean drilling: the Arctic Coring Expedition (ACEX). This technically-challenging expedition recovered the first Cenozoic sediment record from the Arctic Ocean-extending previous records from ~1.5 Ma to an unprecedented ~56 Ma. Glimpses of the breadth of this transformation were even seen during ACEX when the massulae from fresh water ferns were found and the presence of Apectodinium augustum confirmed that the Paleocene-Eocene Thermal Maximum (PETM) was unexpectedly recovered. Soon after the expedition, when the cores were opened and analyzed, ice-rafted debris was found to have occurred much earlier than previously thought-in the Eocene in an environment of high organic carbon content. The initial analyses also revealed an extensive hiatus that occurred between several of the most spectacular sediment cores in terms of color, e.g. turquoise, and structure, starkly contrasting black and white crossbedding that is now dubbed the "zebra" core. The exciting early results attracted other investigators that expanded the scientific investigating team to more than 40 people. This, in turn, extended the analyses to include new studies that revealed surprisingly high Arctic Ocean surface water temperatures and a hydrologically active system during the PETM. Although the hiatus is a lost window in time for the Arctic paleoclimate record, it spawned other studies that integrated the regional tectonic history with ACEX results revealing a major oceanographic reorganization at 17.5 Ma-ventilation of the Arctic Ocean to the North Atlantic through the Fram Strait. In this overview, recent results from the large ACEX scientific "family" are summarized and include: a new age model; detailed analyses of the middle Eocene that document a unique brackish water environment; sea ice and iceberg history reconstructions and provenance from the Eocene to present; evolution of depositional environments that are linked to broader tectonic & subsidence histories; times of isolation and connection to the global ocean; geochemical analyses of the organic carbon-rich sediments; and unique applications of high resolution proxies and cyclostratigraphy.
DE: 4900 PALEOCEANOGRAPHY (0473, 3344)
DE: 9604 Cenozoic
SC: Paleoceanography and Paleoclimatology [PP]
MN: 2007 Fall Meeting