Magnetic mineralogy and its implication of contemporary coastal sediments from South China

Magnetic parameters have been widely used as a rapid, cost-effective, and non-destructive method. To assess whether their magnetic properties reflect the development history in the Pearl River Delta, three sediment cores collected from South China coastal waters were selected for magnetic research. The results indicate that the predominant ferrimagnetic mineral is magnetite, with an additional smaller amount of surprisingly high-coercive greigite. Fine-grained superparamagnetic and single-domain particles of magnetite and the relative contribution of greigite are increased when the total concentration of ferrimagnetic minerals is higher. Three well-known stages of the Chinese history, i.e., iron smelting, cultural revolution, and the latest phase of opening and reforming were identified in the vertical variation of magnetic concentration parameters. Although the record of the three cores is not completely consistent, the results point out that magnetic concentration parameters can reflect the development and pollution history in surrounding coastal areas.