Characteristic Of Magnetic Susceptibility And Its Primarily Interpretation Of Late Cenozoic Sediments Of Liaodong Peninsula

Deposit magnetic susceptibility index mainly depends upon the characteristics of content,variety and granularity of the magnetic mineral, this could recorded and reflected thecomposite information of regional environment variation. In this paper, two types ofsediments which are slope deposit （S1^S4sections）and red weathered crust（S5^S6sections）were chosen from Liaodong Peninsula for magnetic susceptibility measurement.Results showed us the vertical variation characteristics and spatial distribution characteristicsof sediments magnetic susceptibility since late Cenozoic in study area. The authors tried togive a preliminary interpretation for the sedimentary environment and palaeoclimate variationinformation by studying the magnetic susceptibility result. It is concluded that:（1） The slope deposit sections S1^S4chosen from Liaodong Peninsula, its average valueof mass magnetic susceptibility are71.75×10^-8m³/kg,65.81×10^-8m³/kg,68.17×10^-8m³/kg,151.70×10^-8m³/kg, vertical coefficients of variation are23.84%、30.92%、16.50%、39.76%,and frequency-dependent magnetic susceptibility are10.77%,9.67%,9.46%,10.36%, verticalcoefficients of variation are9.82%、14.10%、12.27%、9.46%. The red weathered crust sectionsS5^S6also chosen from Liaodong Peninsula, its average value of mass magneticsusceptibility are305.06×10^-8m³/kg,473.26×10^-8m³/kg, vertical coefficients of variation are26.71%、31.23%and frequency-dependent magnetic susceptibility are14.44%,14.95%,vertical coefficients of variation are9.06%、6.55%.（2） The average value of mass magnetic susceptibility and frequency-dependentmagnetic susceptibility of S1-S6sections in Liaodong Peninsula are obviously different andhave spatial differentiation phenomenon. It reflects that there are almost the same contents ofmagnetic mineral and super paramagnetic ferromagnetic and mineral ultra fine grain in thesediment of the slope deposit （S1-S3sections）. The deposit time, sediment source,depositional environment are approximately consistent. While the content of magneticmineral is high in slope deposit S4section, the deposit time and depositional environment aredifferent from the S1-S3sections. The content of magnetic mineral and super paramagneticferromagnetic and mineral ultra fine grain is very high in the sediment of the red weatheredcrust （S5-S6）, it is significantly different from slope deposit （S1-S4sections）. （3） Much of the Liaodong Peninsula slope deposit were developed during the differenttimes of Quaternary Period, such as S1-S3section were developed during the post latePleistocene which had a arid-cold palaeoclimate environment, but S4section were developedduring the earlier period of Medio-Pleistocene which had a warm and wet palaeoclimateenvironment. However, red weathered crust of Liaodong Peninsula was developed during lateTertiary Period which had a hot and damp climate. It could be reflected that the climatedevelopment of Liaodong Peninsula since late Cenozoic era had such a tendency from wetand warm climate of monsoon late Tertiary Period to semi-humid and semi-dry climate andarid-cold climate of monsoon Quaternary Period.（4） The variation characteristics of slope deposit’s mass magnetic susceptibility,variation characteristics of slope deposit and red weathered crust’s frequency-dependentmagnetic susceptibility can reflect the palaeoclimate variation information to some extent, soit can be used to indicate the palaeoclimate variation in Liaodong Peninsula.