THE RELATION BETWEEN PRODUCTIVITY AND TEMPERATURE IN THE PLIOCENE NORTH-ATLANTIC AT THE ONSET OF NORTHERN-HEMISPHERE GLACIATION - A PALYNOLOGICAL STUDY

High resolution palynological analysis of DSDP Cores 607/607A shows fo r the interval between 2.8 and 2.2 Ma B.P. (which includes the onset o f major northern hemisphere glaciations) a 41 ka cyclicity characteris ed by much higher palynomorph concentrations for the cooler intervals than for the warmer ones. Variation in dilution and concentration of p alynomorphs can neither be explained by differential input of terrigen ous clastics or carbonate, nor by differences in sedimentation rate, s ediment density or selective preservation of palynomorphs. Subdivision of the palynomorph record in terms of autochthonous and allochthonous components, provides a way to detect changes in open ocean productivi ty and transport through time, It seems that a negative correlation be tween productivity and temperature in the latest Pleistocene open Atla ntic had already been established before the major onset of northern h emisphere glaciations. A conceptual model is proposed to explain the o bserved lead of the palynological record relative to the isotope and c arbonate records is proposed. This early response can result from chan ges in North Atlantic surface ocean circulation induced by changing at mospheric circulation.