Geochemical characteristics of sediments from the middle Okinawa Trough since the latest pleniglacial period and periodic characteristics of its sediment sources

Chemical compositions of 21 sediment samples from Core DGKS9603 taken in the middle Okinawa Trough are analyzed by ICP-AES.The characteristics of 18 elements are analyzed.By means of correlation analysis and factor analysis,five factors(F₁,F₂,F₃,F₄,F₅)are acquired and sorted into three major factors.The first factor(F₁),which includes the elements of Fe,Al,V and K,Mg,Rb,etc.,stands for the sediments or iginated from the continent source(for example:the Huanghe River or continental shelf).The second factor(F₂,F₃)is biogenetic derivation factor,including Ca,Sr,Ba,Mn and P.The third factor(F₄,F₅)indicates that sediment compositions are contr olled by volcanism and hydrothermal fluid in the trough,and the element combination of this factor is Na,Co and Ni.Core DGKS9603 can be divided into four sections based on the factor scores of the samples.In Section A the score of the second factor is high and biogenetic sediments are the major source of this section,and also a little material maybe comes from land source.In Section Bthe contents of Na,Co and Ni are higher than those in other sections and the sediments of this section are derived from volcanic activities,including volcanism eruption and hydrothermal activities.In Section C the variety of element contents is small.Terrigenous and biogenetic compositions comprise the sediments.Section Dischiefly composed of terrigenous material that may come from the continental shelf exposed to the air during the latest pleniglacial.These four parts with different sediment sources in this core are coincident with the change of paleoclimate and paleoenvironments,the periodic change of material source corresponds the change of paleoclimate and paleoenvir onments.