Magnetic properties of muddy sediments on the northeastern continental shelves of China: Implication for provenance and transportation
Magnetic properties of muddy sediments on the northeastern continental shelves of China: Implication for provenance and transportation
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DOI：
10.1016/j.margeo.2010.03.009
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发表时间：
2010-08
期刊：
影响因子：
2.9
通讯作者：
Yonghong Wang;Hailiang Dong;Guangxue Li;Weiguo Zhang;T. Oguchi;Min Bao;Hongchen Jiang;Michael E. Bishop
中科院分区：
文献类型：
--
作者：
Yonghong Wang;Hailiang Dong;Guangxue Li;Weiguo Zhang;T. Oguchi;Min Bao;Hongchen Jiang;Michael E. Bishop
淤泥沉积物广泛分布于河口和大陆架，包含有关陆地和沿海过程之间相互作用的重要信息。利用大体积和粒度分级样品分析了中国东北大陆架（包括靠近朝鲜海岸的大陆架）泥质沉积物的磁性，以阐明泥质沉积物的来源和运输。磁性矿物的类型，浓度和粒度测定和所有样品被发现占主导地位的磁铁矿。浙闽沿海泥质沉积物的磁化率（χ）和饱和等温剩磁（SIRM）值最高，而南黄海中部和东南部以及朝鲜海峡西部泥质沉积物的磁化率和饱和等温剩磁（SIRM）值较低，反映磁性矿物含量较低。南黄海中部的磁性颗粒以单畴亚铁磁性颗粒为主，而渤海的磁性颗粒则以超顺磁性颗粒为主。北黄海和沿着浙闽海岸的磁性颗粒组合以SP和粗多畴（MD）颗粒为主。岩石沉积物粒度不是影响研究区泥质沉积物磁性的主要因素。相反，陆源输入和水动力输运过程主要控制磁性，长江和黄河沉积物的贡献最大。这一观察适用于整个研究区，虽然陆源磁性矿物浓度随着距离河口的增加而减少，这是由于分选和混合与其他沉积物的弱磁签名。细菌磁小体在南黄海中部也起着重要作用。
Mud deposits are widespread in estuaries and on continental shelves, and contain important information regarding interactions between terrestrial and coastal processes. Magnetic properties of muddy sediments from the northeastern continental shelves of China, including shelves close to Korean coasts, were analyzed using bulk and size-fractionated samples to elucidate muddy sediment sources and transport. Types, concentration, and granulometry of magnetic minerals were determined and all samples were found to be dominated by magnetite. Muddy sediments from the Zhemin coast (off the Zhejiang and Fujian coasts) have the highest magnetic susceptibility (χ) and saturation isothermal remanent magnetization (SIRM) values, while those from the central and southeastern South Yellow Sea and the western Korea Strait have lower values reflecting lower magnetic mineral concentrations. Single domain ferrimagnetic grains dominate the magnetic particles in the central South Yellow Sea, while superparamagnetic (SP) grains contribute significantly to the magnetic grains in the Bohai Sea. SP and coarse multi-domain (MD) grains dominate magnetic grain assemblages in the North Yellow Sea and along the Zhemin Coast. Rock sediment particle size is not a major factor affecting the magnetic properties of the mud deposits in the study area. Rather, terrigenous inputs and hydrodynamic transport processes primarily control the magnetic properties, and sediments from the Changjiang and Huanghe rivers make the most significant contribution. This observation applies to the whole study area, although terrigeneous magnetic mineral concentrations decrease with increasing distance from the river mouths due to both sorting and mixing with other sediments with weak magnetic signatures. Bacterial magnetosomes also play a role in the central South Yellow Sea.