全新世渤海泥质沉积物地球化学特征

Geochemical characteristics of sediments in the Bohai Sea mud area during Holocene

对渤海泥质区柱状沉积物的粒度与化学成分的分析及AMS14C测年数据表明,全新世以来本区泥质沉积物的物质来源与沉积环境较为稳定。R型因子分析得出三种主要组合类型,以Ca、Ti和Mn为代表,分别对应黄河物质影响、陆源细粒物质输入和海洋自生作用。其中西南部与中部泥形成于约6000aB.P.以来,黄河物质影响较强,主要在潮余流的作用下搬运后沉积下来。北部泥自早全新世之前便已开始形成,且主要沉积于高海面之前,受滦河物质作用相对较强。南部和北部泥质沉积年代存在明显差异,受水深、离岸距离、海平面高度等多种因素影响。尽管距黄河口较近,但区内沉积速率远低于中国近海其他泥质体,这与渤海环流状况及泥沙运移方向关系密切。

Based on the measurements of grain-size, AMS ^14C dating, major and trace elements, formation time and sources of muddy deposits in the Bohai Sea mud area （BSMA） are discussed. The results show that sediment sources and depositional environments of the muddy system remained relatively stable during Holocene. Three groups representing respectively by Ca, Ti and Mn can be derived from R-model factor analysis, corresponding to the impact of the Yellow River sediment, input of fine-grained terrigenous sediments and marine autogenic deposit. The mud in the southwestern and middle part was formed since about 6000 a B. P., and the Yellow River sediments were transported to and deposited there under the process of tidal residual currents. The mud in the northern part began to deposit in early Holocene, especially before middle Holocene, when material from the Luanhe River affected obviously. Different deposition time of the muddy sediments in the south and north suggests the controls of water depth, distance off the coastline and sea-level changes. Sedimentation rate in the BSMA is far slower than other muddy wedges in the China＇s seas despite of close distance from the Yellow River mouth, which can be explained by the Bohai Sea circumfluence and transporting direction of fine-grained sediments discharged into the Bohai Sea.