北部湾SO-50柱状沉积物地球化学特征及其物源分析

通过对北部湾SO-50柱状沉积物进行粒度、Sr-Nd同位素、主微量元素及AMS14C分析，结果表明该柱状沉积物可以划分为两段，即上段（0~540 cm，0~3.0 ka BP）和下段（540~571 cm，3.0~3.3 ka BP），它们反映了不同的物质源区贡献。下段较上段砂含量相对较高，主量元素（除SiO₂外）及稀土元素含量相对减少，87Sr/86Sr与ε_Nd除异常点外，总体变化幅度不大。研究结果显示SO-50柱状沉积物的物质来源比较稳定，具有强烈的陆源特征，下段沉积物的源区主要是琼州海峡东侧原有沉积物的再搬运和台湾岛河流携带沉积物的混合，上段沉积物除了琼州海峡东侧和台湾岛的贡献外，周边陆区海岸侵蚀物的贡献相对加强。根据SO-50柱状沉积物的研究结果表明，北部湾东部泥质区的物质来源除了琼州海峡东侧沉积物和沿岸侵蚀物的贡献外，台湾岛河流携带的沉积物对其影响也应引起重视。

Geochemical characteristics and sediment provenance of Core SO-50 sediments in the Beibu Gulf

The provenance of Core SO-50 sediments were discussed in this paper based on grain-size, Sr-Nd isotopes, major and trace elements and AMS14C dating. Results showed that Core SO-50 could be divided into two sedimentary units:(1) the upper unit(0-540 cm,0-3.0 ka BP), (2) the lower unit(540-571 cm,3.0-3.3 ka BP). Compared with the upper unit, the sand content increased and the content of major elements (excepting SiO₂) and REE decreased. In addition to the abnormal value, the trends of 87Sr/86Sr and ε_Nd were relatively stable. The results suggested that Core SO-50 sediments were mainly derived from the eastern Qiongzhou Strait, Taiwan islands and the surrounding coastal. In the lower unit were primarily a mixture of the eastern Qiongzhou Strait and Taiwan islands, and in the upper unit, in addition to the contribution of the eastern Qiongzhou Strait and Taiwan islands, the supply of the surrounding coastal was increased. Therefore, the contribution of Taiwan islands to the Beibu Gulf area should be paid more attention in the future studies.