中国东部海域表层沉积物磁化率空间分布特征

Distribution Characteristics of Magnetic Susceptibility of the Surface Sediments in the East China Seas

海洋沉积物的磁性参数是反映物质来源、沉积环境变化的重要代用指标。本文基于中国东部海域的176个沉积物样品,通过粒度、磁化率的测试分析,揭示了磁化率和粒度的空间分布特征,并探讨了磁化率和粒度之间的关系及其环境指示意义。研究表明,三大海域磁化率(χ)存在显著差异,东海磁化率最高,渤海次之,黄海最低,即χdonghai>χbohai>χhuanghai,磁化率在河口、沿岸偏高,并呈现出向外海方向缓慢递减的趋势,这反映了三大海域的物源差异以及在不同水动力条件下的物源供给、扩散和运移。磁性参数与粒度的相关性研究表明,多重因子的综合作用使得χfd%作为整个海域沉积物的粒度代用指标并不理想。磁性参数的变化与沉积动力密切相关,水动力越强、水介质扰动性越大,磁性参数越离散。

Magnetic parameters of marine sediment is an important substitute index of material source and sedimentary environment changes.This study is based on the 176 surface sediment samples of the East China Seas:by particle size test and magnetic susceptibility analysis,it reveals the spatial distribution characteristics of magnetic susceptibility and grain size,and also discusses the relationship between the magnetic susceptibility,grain size and its environmental significance.Research shows that:There are significant differences of magnetic parameters in three Marine,χdonghai>χbohai>χhuanghai,the east seas high magnetic susceptibility value areas majorly distribute estuaries and coast,and present a slowly decreasing trend toward the sea,reflecting the differences of material source,supply,proliferation and migration under different hydrodynamic conditions in three waters.The correlation of frequency magnetic susceptibility and grain size shows that the combination of multiple factors make theχfd%as the sea shelf sediment grain size parameters is not ideal.the variation of the magnetic parameters of the shelf sediments is closely related to the sedimentary dynamics,the stronger the hydrodynamic is,the stronger the disturbance of the water medium is,the greater the change of the magnetic susceptibility,the more discrete the magnetic parameters.