Organic Biomarker Record of Oceanographic and Environmental Changes off Central Peru During the Last 300 Years

On the Peru margin, high surface-water productivity and associated vertical fluxes and an intense Oxygen Minimum Zone (OMZ) favours the preservation of high resolution sedimentary records of climate signals and water column processes. In the framework of the PALEOPECES project, two box cores were collected in the central Peruvian margin, in the shelf off Callao (12°00'S, 72°42'S, 184 m) and in the upper slope off Pisco (14°07'S, 76°30'S, 299 m). On-going molecular organic geochemical studies and complementary mineralogical and organic elemental analyses aim to reconstruct climatic, environmental and ecosystem variability within the last 200 years on an interannual/decadal time scale. Alkenone-SST data show variability within the last 300 years which mainly mirrors ENSO phases, although changes in the SST signal are much attenuated, and permit to extend instrumental data records. Organic biomarkers diagnostic for major phytoplankton groups are used as a tool to assess changes in the productivity patterns as a response to changing upwelling intensity and to El Nino/El Nina phases. Furthermore, patterns of higher-plant lipids are linked to changes in the eolian forcing and/or in the intensity of transport processes.