The Chukchi Borderland,including the Northwind Ridge area,is undergoing significant changes in sea ice melting(Stroeve et al.,2012),as well as fresh water storage and biological productivity in recent climate warming(Rabe et al.,2011; Arrigo et al.,2008).To better understand these recent trends,it is necessary to examine the effects of past climate changes in this region using sediment core proxy records.Foraminiferal assemblage and planktonic foraminiferal stable oxygen and carbon isotopes have been investigated on core ARC3-P37,retrieved from the Northwind Ridge,in order to reconstruct the water column structure and circulation changes in response to climate variation.The abrupt increase of foraminiferal abundance may indicate warm intervals with pacific inflow to the Western Arctic Ocean.Planktonic species Neogloboquadrina pachyderma(sin.)(Nps)dominates the foraminiferal assemblage by over 90%.Benthic assemblage mainly comprises of deep water dwellers Cibicidoides wuellerstorfi and Oridorsalis umbonatus.The occurrence of Atlantic species Cassidulina neoteretis during cold periods indicates the deepening of Arctic intermediate water.Nps-δ13C is generally heavy during warm intervals,reflecting good ventilation and high productivity.Nps-δ18O variation is complicated and affected by its habitat,water temperature,halocline depth,meltwater etc.,and generally showing heavy values during cold periods,while light values corresponding to meltwater input.Above the brown layer B2b in Marine Isotopic Stage(MIS)3,light Nps-δ18O is affected by warm sea water and meltwater discharge; while below B2b,the heavy Nps-δ18O during warm intervals may suggest shallowing of the halocline and the migration of Nps habitat to deeper layers.