The PACHIDERME oceanographic cruise is organized within the framework of Chilean-French-German-Norwegian collaborations based on the Southeastern Pacific paleoceanographic studies. It will be lead by the chief Scientist : Catherine KISSEL, from the French Laboratoire des Sciences de l’Environnement et du Climat, based in Gif-sur-Yvette, France.

The Chilean Principal Investigator of the cruise will be Carina Lange.

Objectives of the cruise

The objective of the cruise is to obtain high sedimentation rate long cores in key areas along the southern Chilean coast to reconstruct past changes of the climatic regimes of the Southeastern Pacific. The location of this area is critical with respect to the high southern latitudes, the Antarctic Peninsula, the Drake passage and the tropical Pacific.

Coring sites have been chosen in areas with high deposition rate and offer promising targets for high resolution paleoclimate studies. They are distributed from the inland waterways to off the bounding islands along the outer continental shelf and slope. Distributed both in latitude and along these longitudinal transects from the mainland to the open ocean, they will allow the scientists to study the interplay between oceanic dynamics and glacial response in Antarctica and the Southern South American ice sheets/caps.

The main goals of the cruise are :

1) to determine the thermocline and intermediate water ventilation in the far Southeastern Pacific ;

2) to study the past latitudinal intensity variability of the westerly wind belt ;

3) to establish the chronology for the retreat of the major Patagonian/Cordillera Darwin glaciers since the LGM to address questions concerning inter-hemispheric synchronism of climate change ;

4) to establish the climatic variability around the mean state at decadal periods.

In order to achieve these goals, multi proxy chronological, isotopic, geochemical, micropaleontological, sedimentological and magnetic investigations are planned in a collaborative effort between the different Chilean, French, German and Norwegian groups involved.

These multi-proxy analyses will help reconstructing past changes in the temperature, salinity and density of waters at different depths. The detrital fraction will also be analyzed in detail in order to define the changes in the sedimentary supply depending on the time periods. The stratigraphic aspect will be studied using both oxygen isotopes, radiocarbon dating, radiometric dating of tephra layers (Ar/Ar) and analysis of the geomagnetic vector field, a stratigraphic tool independent of climatic conditions.