LATE QUATERNARY SEDIMENT DATING AND QUANTIFICATION OF LATERAL SEDIMENT REDISTRIBUTION APPLYING TH-230(EX) - A STUDY FROM THE EASTERN ATLANTIC SECTOR OF THE SOUTHERN-OCEAN

High-resolution records of the natural radionuclide Th-230 were measur ed in sediments from the eastern Atlantic sector of the Antarctic circ umpolar current to obtain a detailed reconstruction of the sedimentati on history of this key area for global climate change during the late Quaternary. High-resolution dating rests on the assumption that the Th -230(ex) flux to the sediments is constant. Short periods of drastical ly increased sediment accumulation rates (up to a factor of 8) were de termined in the sediments of the Antarctic zone during the climate opt ima at the beginning of the Holocene and the isotope stage 5e. By comp aring expected and measured accumulation rate of Th-230(ex), lateral s ediment redistribution was quantified and vertical particle rain rates originating from the surface water above were calculated. We show tha t lateral contributions locally were up to 6.5 times higher than the v ertical particle rain rates. At other locations only 15% of the expect ed vertical particle rain rate were deposited.