COMPARISON OF MAGNETIC SUSCEPTIBILITY OF LATE QUATERNARY SEDIMENT DERIVED FROM SLOPES IN THE SOUTH CHINA SEA AND IMPLICATION FOR PALEOCEANOGRAPHY

Based on the comparison of the magnetic susceptibility variations of late Quaternary sediment derived from slopes neighboring the Xisha Trough,Dongsha Islands,and southern slope in the South China Sea,we preliminarily analyze the relationship between magnetic susceptibility and calcium carbonate percentage.According to the characteristics of magnetic susceptibility changes,the slope neighboring the Xisha Trough and southern slope should be regarded as one unit,and the slope neighboring the Dongsha Islands another unit.While the late Quaternary magnetic susceptibility curves from the former unit is characterized by peaks during the transitions from marine isotope odd stage to marine isotope even stage,and by valleys during the transitions from marine isotope even stage to marine isotope odd stage,the late Quaternary magnetic susceptibility curves from the latter unit is parallel with the foraminifera oxygen isotope curve.In each unit,the common characters of magnetic susceptibility can be used for stratigraphic division and correlation,but some magnetic susceptibility during the late Quaternary fluctuated locally,and therefore its curve is not a tool for regional stratigraphic correlation.There are two kinds of relationships between magnetic susceptibility and calcium carbonate percentage curves,i.e.,mirror type and parallel type,but the relationships do not mean a necessary link between magnetic susceptibility and calcium carbonate percentage.The causes of sediment susceptibility changes in the slopes seem related with the changes in terrigenous flux in the glacial-interglacial cycles.The sediment susceptibility in some local area is probably influenced severely by early diagenesis.