HR: 0800h
AN: GP21A-0020    [Abstracts]
TI: IODP Expedition 303 (North Atlantic): Excursions and Reversals in the Brunhes and Matuyama Chrons
AU: * Channell, J E
EM: jetc@geology.ufl.edu
AF: University of Florida, Dept. Geological Sciences, POB 112120, Gainesville, FL 32611 United States
AU: Mazaud, A
EM: mazaud@lsce.cnrs-gif.fr
AF: Laboratoire des Sciences du Climat et de l'Environnement, Avenue de la Terrasse, Gif-sur-Yvette, 91198 France
AU: Stoner, J S
EM: jstoner@coas.oregonstate.edu
AF: Oregon State University, College of Oceanic and Atmospheric Sciences (COAS), Corvallis, OR 97331 United States
AB: The primary objective of IODP Expedition 303 (Sept.-Nov., 2004) was to recover complete and continuous records of Pliocene-Quaternary millennial-scale environmental and geomagnetic variability, and place these records into high-resolution isotopic and magnetic stratigraphies (including relative paleointensity). Some of the Exp. 303 site locations (Orphan Knoll, Eirik and Gardar Drifts, and DSDP Site 609) have already been instrumental in developing marine records of suborbital climate variability for the last climate cycle, and the goal of Exp. 303 was to extend the records back through the Quaternary and into the Pliocene. High mean sedimentation rates (15-20 cm/ky) at sites located on Orphan Knoll (Site U1302/3), Eirik Drift (Sites U1305 and U1306) and Gardar Drift (Site U1304) have resulted in shipboard records of excursions and reversals in the Brunhes and Matuyama Chrons. Site U1308 (DSDP Site 609) has lower mean sedimentation rate (7.9 cm/kyr) and extends the record into the Gauss Chron to ~3.1 Ma. Initial u-channel magnetic data support the existence of a number of polarity excursions in the Matuyama Chron, but only a single polarity excursion (Iceland Basin Event) has so far been observed in the Brunhes Chron. The Matuyama-Brunhes (M-B) polarity reversal yields virtual geomagnetic polar (VGP) paths that are reminiscent of those recovered from the northern Gardar and Bjorn drifts during ODP Leg 162. VGP clusters in the South Atlantic and off NE Asia accompany a Pacific loop, in what appears to be a repetitive but complex pattern for the M-B transition recorded in 9 holes from three Exp. 303 North Atlantic sites.
DE: 1513 Geomagnetic excursions
DE: 1520 Magnetostratigraphy
DE: 1535 Reversals: process, timescale, magnetostratigraphy
SC: Geomagnetism and Paleomagnetism [GP]
MN: Fall Meeting 2005