长江与黄河河口沉积物磁性特征对比的初步研究

根据2001年8月和9月分别采自黄河与长江河口沉积物样品的磁性测量和粒度分析,探讨长江和黄河河口沉积物的磁性特征及其差异。长江河口沉积物中亚铁磁性物质的含量高于黄河口,但长江口与黄河口沉积物中都是亚铁磁性矿物主导了样品磁性特征,亚铁磁性矿物晶粒都以假单畴-多畴为主。相比黄河口沉积物,长江口沉积物不完整反铁磁性物质对磁性特征的的贡献较小。长江与黄河河口的这种磁性特征主要反映了不同的沉积物来源的控制影响。此外,无论是长江口还是黄河口沉积物,磁性参数χARM、χfd%与沉积物细粒级组分存在显著的相关性,表明这两个参数作为粒度的代用指标具有普遍性。

A Preliminary Comparison of Magnetic Properties of Sediments from the Changjiang and the Huanghe Estuaries

Magnetic properties of sediments from the Changjiang and the Huanghe Estuaries have been studied on the basis of magnetic measurement and grain size analysis. The results show that the magnetic properties of the sediments are dominated by ferrimagnetic magnetite, and higher concentration of ferrimagnetic minerals is observed for the Changjiang Estuary sediments. The pseudo single domain and multi domain particles are the main carriers of the ferrimagetic magnetite of the sediments in the Changjiang and Huanghe Estuaries, and single domain and superparamagnetic particles are also present in the sediments with higher concentration occuring in the Changjiang Estuary. The magnetic properties of sediments from the Changjiang and the Huanghe Estuaries suggested that the provenance of sediments controlled the magnetic features. At the same time, obvious correlation exists between χ ARM、 χ fd % and fine particles of the sediments in the Changjiang and Huanghe estuaries.