Late Quaternary paleoenvironmental history of Chile and the adjacent Southeast Pacific (ODP Leg 202 Sites 1233-1235).
The Chilean continental margin (Sites 1233 to 1235) is characterized by exceptionally high sedimentation-rates in the order of 1m/ka providing a huge potential for ultra-high resolution studies. Studies on short sediment cores from the region indicate that Holocene continental and ocean climate changes are intimately coupled and reveal linkages to both the tropics and high southern latitudes (Hebbeln et al., 2002; Lamy et al., 2001; Lamy et al., 2002). Detailed investigations were conducted on Site 1233 sediments within the framework of the German IODP/ODP Priority Program. We showed for example that the complete ~70-kyr-long alkenone SST record at Site 1233 closely follows millennial-scale sea surface temperature (SST) fluctuations as observed in Antarctic ice cores (Kaiser et al., 2005; Lamy et al., 2004). In addition, these millennial-scale SST variations parallel compositional changes in the terrigenous sediment input and paleosalinity variations, both of which reflecting Patagonian ice-shield variability (Kaiser et al., in press; Lamy et al., 2004). Currently, we are further increasing the resolution of our records and the density of 14C datings in order to further explore the exceptional potential of Site 1233 for paleoclimate reconstructions.
A major goal for the northern ODP Sites 1234 and 1235 is to follow the continental climate changes recorded at Site 1233 further north into Central Chile where the ice cover of the hinterland was restricted to mountain glaciers. Available data from short cores suggest that rainfall changes related to latitudinal shifts of the westerly wind belt play a crucial role in this region and further north (Lamy et al., 1998; Lamy et al., 1999). Oceanographically, Sites 1234/1235 are strongly influenced by coastal upwelling. Here, we are particularly interested in analysing changes in the terrigenous sediment supply. These data will be linked to our continental climate reconstructions and additional paleoceanographic proxy data provided by our collaborators, which will result in a comprehensive multi-proxy synopsis of continental and ocean climate changes at the southern end of the Peru-Chile Current system covering the last glacial-interglacial cycle.
Fig. 1: Sea surface temperature and sea surface salinity distribution off central Chile with locations of ODP Site 1233-1235.
Fig. 2: Antarctic timing of millennial-scale sea surface temperature patterns recorded at ODP Site 1233 (after Kaiser et al., 2005 and Lamy et al., 2004).
Fig. 3: Paleosalinity changes over the last deglaciation at ODP Site 1233. Note the pronounced decrease of salinities after the regional glacial maximum between ca. 17.5 and 18 kyr BP. (after Lamy et al., 2004).
AWI investigators
External Collaborators
Helge Arz (GFZ-Potsdam, Germany)
Ricardo de Pol-Holz, (WHOI, USA)
Dierk Hebbeln (MARUM-University of Bremen, Germany)
Jerome Kaiser (GFZ-Potsdam, Germany)
Ulysses Ninnemann (University of Bergen, Norway)
Philippe Martinez (University of Bordeaux, France)
Alan Mix (Oregon State University, USA)
Joseph Stoner (Oregon State University, USA)
Funding
IODP/ODP Priority Program of the DFG
Key Publications
Kaiser, J., Lamy, F. & Hebbeln, D., 2005. A 70-kyr sea surface temperature record off southern Chile (ODP Site 1233). Paleoceanography, 20: doi:10.1029/2005PA001146.
Kaiser, J., Lamy, F., Arz, H. W., Hebbeln, D.(2006).Variability of sea surface temperatures off Chile and the dynamics of the Patagonian Ice Sheet during the last glacial period based on ODP Site 1233., Quaternary International.
Lamy, F.(2006).Postglacial South Pacific., Encyclopedia of Quaternary Science,1856-1866.
Lamy, F., Kaiser, J., Ninnemann, U., Hebbeln, D., Arz, H. W.& Stoner, J. (2004). Antarctic Timing of Surface Water Changes off Chile and Patagonian Ice Sheet Response. Science 304 : 1959-1962 (2004). Lynch-Stieglitz, J. (2004). OCEAN SCIENCE: Hemispheric Asynchrony of Abrupt Climate Change. Science 304 : 1919-1920 (2004). Perspectives on Lamy et al., 2004