HR: 13:40h
AN: GC53A-01 INVITED     [Abstracts]
TI: Late Quaternary Paleoenvironmental History of the Peru-Chile Current System and Adjacent Continental Chile
AU: * Lamy, F
EM: flamy@gfz-potsdam.de
AF: GeoForschungsZentrum-Potsdam, Telegrafenberg, Potsdam, 14473 Germany
AU: Hebbeln, D
EM: dhebbeln@uni-bremen.de
AF: Research Center for Ocean Margins, Universitaet Bremen, Klagenfurter Strasse, Bremen, 28359 Germany
AU: Kaiser, J
EM: kaiserj@uni-bremen.de
AF: Research Center for Ocean Margins, Universitaet Bremen, Klagenfurter Strasse, Bremen, 28359 Germany
AU: Mohtadi, M
EM: mohtadi@uni-bremen.de
AF: Research Center for Ocean Margins, Universitaet Bremen, Klagenfurter Strasse, Bremen, 28359 Germany
AU: Ninnemann, U
EM: ulysses@uib.no
AF: Department of Earth Sciences and Bjerknes Center for Climate Research, University of Bergen, Allegaten 41, Bergen, 5007 Norway
AB: A combined analysis of terrigenous and biogenic compounds in marine sediments from the Chilean continental margin allows detailed reconstructions of the paleoclimatic and paleoceanographic history of this region during the last ca. 120,000 years. Based on several sediment cores recovered during two German cruises and ODP Leg 202 (Site 1233), we found evidence for changes both in continental rainfall, most likely induced by latitudinal shifts of the Southern Westerlies, and marine productivity as well as sea surface temperature and salinity changes within the Peru-Chile Current system on time scales ranging from Milankovitch to centennial-scale. On Milankovitch time-scales, we found strong evidence for precession-controlled shifts of the Southern Westerlies implying for example generally more humid conditions during the LGM and a trend towards more arid climates during the deglaciation culminating in the early Holocene. These shifts are paralleled by paleoceanographic changes indicating generally higher productivity during the LGM mainly caused by increased advection of nutrients from the south through an enhanced Peru-Chile current. North of 33øS, these general productivity patterns are complicated by additional impacts from the tropics resulting in maximum paleoproductivity during the deglaciation and prior to the LGM. On shorter time-scales, extremely high resolution sediment cores from the southern Chilean margin provide evidence of significant short-term Holocene climate variability with bands of variability centred at ca. 900 and 1500 years, periodicities also well known from Northern Hemisphere records. Recently drilled ODP Site 1233 allowed to prolong these records into the last glacial. The available data show millennial-scale SST changes that closely follow the temperature pattern known from Antarctic ice-cores. Including other records from the Southern Hemisphere mid-latitudes, our data suggest a quasi-hemisphere-wide response that is consistent with the bipolar see-saw mechanism but may also imply a more prominent role of the Southern Hemisphere in the origin and transfer of millennial-scale climate variations during the last glacial. In addtion, Site 1233 offers the excellent opportunity to compare continental and marine paleoenvironmental signals within the same well-dated archive suggesting a lagged response of the terrestrial signal most likely related to climate inertia of the Patagonian ice-sheet.
DE: 9355 Pacific Ocean
DE: 9360 South America
DE: 3344 Paleoclimatology
DE: 4267 Paleoceanography
SC: Global Climate Change [GC]
MN: 2004 AGU Fall Meeting