Partitioning of eolian and hemipelagic sediment in eastern equatorial Pacific core TR 163-31B and the late Quaternary paleoclimate of the northern Andes

We apply simple eolian-hemipelagic mixing model to characterize the terrigenous sediment component in well-dated deepsea core TR163-31B raised from south of the Carnegie Ridge, 300 km west of the coast of Ecuador, The terrigenous component forms 11-19% of the sediment in this pelagic core. The relative amount of hemipelagic and eolian material was determined by comparison of the 1-30 mu m grain size distribution of the terrigenous fraction to that from a mixing model constructed from eolian and hemipelagic end members. Results indicate that hemipelagic deposition 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 than 15 ha. This depositional pattern generally matches the paleoclimatology of the northern Andes, specifically cooler and wetter conditions during stadials and warmer and drier conditions during interstadials and the Holocene.