台湾海峡西部表层沉积物磁化率特征
Distribution Characteristics of Magnetic Susceptibility of Surficial Sediments in the Western Taiwan Strait
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摘要: 为研究台湾海峡西部表层沉积物磁化率变化特征及其控制因素，对采自平潭至汕尾近海海域的228个表层沉积物样品进行了磁化率分析，得出低频磁化率和频率磁化率值均呈从近岸向外海递减趋势，且厦门湾以北近岸海域的低频磁化率明显高于厦门湾以南的，频率磁化率在平潭岛外侧和汕尾近岸海域相对较高，且自平潭岛向南，有一明显的递减趋势。通过和前人关于台湾海峡西部沉积物类型和重矿物分布研究的对比发现台湾海峡西部表层沉积物磁化率在近岸细粒沉积物中高，外海粗颗粒沉积物中低，磁化率值的变化趋势和沉积物中磁铁矿含量的变化趋势一致，说明台湾海峡西部磁化率和频率磁化率主要受沉积作用和沉积物来源的影响。Abstract: Magnetic susceptibility of 228 surface sediments, sampled from the offshore between Pingtan to Shantou, were measured with an attempt to understand the distribution characteristics and their dominative factors of magnetic susceptibility in the western Taiwan Strait.The results showed that the values of low frequency mass specific susceptibility(χlf) and frequency dependent susceptibility(χfd%) decreased gradually from shore to offshore, and the values of χlf were apparently higher in area north to the Xiamen Bay than those from the south. Our study also showed that χfd% at the east of Pingtan Island and the coastal areas of Shantou were relatively high Furthermore, it was obvious that the values decline from Pingtan Island to the south. In comparison with previous studies related to sedimentary types and heavy mineral distribution of the western Taiwan Strait, we discovered susceptibility the values were higher in the fine grained sediments nearshore while lower in the coarse grained sediments offshore in the western Taiwan Strait. The values of magnetic susceptibility correlated well with the content of magnetite, suggesting magnetic susceptibility and frequency dependent susceptibility were dominated by sedimentation process and the source of sediments.
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