PARTITIONING OF EOLIAN AND HEMIPELAGIC SEDIMENT IN EASTERN EQUATORIALPACIFIC CORE TR 163-31B AND THE LATE QUATERNARY PALEOCLIMATE OF THE NORTHERN ANDES

We apply simple eolian-hemipelagic mixing model to characterize the te rrigenous sediment component in well-dated deepsea core TR163-31B rais ed from south of the Carnegie Ridge, 300 km west of the coast of Ecuad or, The terrigenous component forms 11-19% of the sediment in this pel agic core. The relative amount of hemipelagic and eolian material was determined by comparison of the 1-30 mu m grain size distribution of t he terrigenous fraction to that from a mixing model constructed from e olian and hemipelagic end members. Results indicate that hemipelagic d eposition dominated this region from approximately 21.5 to 28 ha (C-14 age) and 15 to 17.5 ha, that both components are important from 17.5 to 21.5 ha, and that the eolian component dominated sediment younger t han 15 ha. This depositional pattern generally matches the paleoclimat ology of the northern Andes, specifically cooler and wetter conditions during stadials and warmer and drier conditions during interstadials and the Holocene.