HR: 0800h
AN: PP51A-1328    [Abstracts]
TI: Duration of Pliocene Ice-Rafting Events Offshore of Prydz Bay, Antarctica, Derived From Extraterrestrial Helium-3
AU: * McAuley, A
EM: mic832@aol.com
AF: Lamont-Doherty Earth Observatory, 61 Route 9W, Palisades, NY 10964 United States
AU: Williams, T
EM: trevor@ldeo.columbia.edu
AF: Lamont-Doherty Earth Observatory, 61 Route 9W, Palisades, NY 10964 United States
AU: Winckler, G
EM: winckler@ldeo.columbia.edu
AF: Lamont-Doherty Earth Observatory, 61 Route 9W, Palisades, NY 10964 United States
AB: The sediment record of ODP Site 1165, located 400 km offshore of Prydz Bay, Antarctica, contains layers rich in ice-rafted debris (IRD) dating from the Early Miocene to the present. The IRD represents pulses of icebergs from the Lambert Glacier and the Antarctic coast west of the site. If the duration of the ice-rafting events is short, they are likely to represent relatively rapid deglaciations of the continent. Alternatively, the IRD could be concentrated in these layers by winnowing or a reduced sedimentation rate. In order to distinguish between these possibilities we have measured helium isotopes across two of the layers. Interplanetary dust particles (IDPs) are enriched in helium-3 compared to terrestrial materials and they are deposited at a relatively constant rate, thus providing a means of determining the (relative) duration of the ice-rafting event. IDPs and helium-3 are diluted one of the Pliocene IRD-rich layers, indicating relatively fast deposition and increased iceberg flux, probably during deglaciation.
DE: 9310 Antarctica
DE: 9604 Cenozoic
DE: 2129 Interplanetary dust
DE: 3022 Marine sediments--processes and transport
DE: 1040 Isotopic composition/chemistry
SC: Paleoceanography and Paleoclimatology [PP]
MN: 2004 AGU Fall Meeting