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磁学可能是南海深海平原古环境研究取得突破的关键方面之一。众多磁学参数中,磁化率是最基本、最综合反映沉积物磁性矿物总体状况的参数,非磁滞剩磁对单畴颗粒含量敏感,而且单畴颗粒是剩磁的主要携带者,结合粒度、碎屑矿物丰度等数据探索南海深海平原柱状样QD189磁化率和非磁滞剩磁地质含义。在磁化率大于45×10-5层位和481 cm以浅的磁化率小于45×10-5的层段,磁化率、2~5粒级含量、ARM和ARM@20m T变化一致性较好,2~5粒级软磁性多畴颗粒含量变化可能是这些层位磁化率变化的主要原因。在808~488 cm层段内,小于45×10-5的磁化率与2~5粒级含量、ARM和ARM@20m T变化总体上一致性较差,磁化率变化机制有待进一步研究。2~5粒级是QD189重要的较粗粒级组分,大体上以深度350 cm为界具有下层段含量较高且粒度变化大、上层段含量较低且粒度变化小的特点。ARM@20m T比ARM更加真实地表示QD189单畴颗粒含量,除了单畴颗粒外,9~12粒级假单畴、多畴颗粒矿物对665~48 cm层段的ARM可能有一定贡献,其中,层段548~310 cm的ARM中可能还有6~9粒级多畴颗粒的贡献。通过碎屑矿物丰度、火山玻璃丰度和(或)磁化率异常峰值的对应关系识别出6次火山活动,火山玻璃丰度的分布特点还揭示出QD189中普遍发生生物扰动作用。
Magnetism may be one of the key aspects of paleo-environmental research in the deep-sea plain of the South China Sea. Among many magnetic parameters, the magnetic susceptibility is the most basic and most comprehensive parameter that reflects the overall condition of the sedimentary magnetic minerals. The non-hysteresis remanence is sensitive to the content of single-domain particles, and the single-domain particles are the main carriers of remanence. Combined with the particle size , Detrital ore abundance and other data to explore the South China Sea deep columnar-like QD189 magnetic susceptibility and non-hysteresis remanent geological implications. The magnetic susceptibility, grain size of 2 ~ 5 μm, the consistency between ARM and ARM @ 20 m T are better in the intervals with the susceptibility greater than 45 × 10-5 and the shallow 481 cm with the susceptibility less than 45 × 10-5 The variation of magnetic susceptibility of 2 ~ 5 grain-size soft magnetic multi-domain particles may be the main reason for the change of magnetic susceptibility of these layers. In the interval from 808 to 488 cm, the magnetic susceptibility less than 45 × 10-5 and the content of 2 ~ 5μm grain size, the overall consistency between ARM and ARM @ 20m T is poor, and the mechanism of magnetic susceptibility changes remains to be further studied. 2 ~ 5 grain size is an important coarser grain grade component of QD189. Generally, the grain size of lower QD189 is larger and the variation of grain size is larger. The upper grain size is lower and the change of grain size is smaller. ARM @ 20m T represents the content of QD189 monodispersion more realistically than ARM. In addition to monodomain particles, the 9-12μm pseudo- and multidomain particles may contribute to the ARM at 665-48 cm, Among them, there may be 6 ~ 9 multi-domain particles in 548 ~ 310 cm ARM in the interval. Six volcanic activities were identified through the correlation between detrital mineral abundance, volcanic glass abundance and (or) abnormal peak of magnetic susceptibility. The distribution of volcanic glass abundance also revealed the general biotic disturbance in QD189.