CHEMICAL-SPECTRA SIMILARITIES AND DIFFERE NCES IN A CLIMATIC SEDIMENTARY CYCLE - EXAMPLE OF THE UPPER PLEISTOCENE FROM THE SITE ODP-852C

Spectrochemical analyses of Upper Pleistocene sediments from the Easte rn Equatorial Pacific show a great variability of sedimentary signal i n an upwelling equatorial zone where the climatic fluctuations are wea kly contrasted. The chemical composition of these carbonate pelagic oo zes characterizes the importance of biogenic and terrigenous fluxes. C omparative analysis of geochemical assemblages of sediments deposited during glacial and interglacial periods emphasizes the different behav iour of Silicon and magnesium. The depletion of nutrient supplies and the occurrence of biolimiting metals during glacial events reduce the siliceous and carbonate biogenic productivity.