深圳湾西北部海域表层沉积物的分布特征及输运趋势

Sediment Grain Size Characteristics and Transport Patterns in the Northwestern Shenzhen Bay,China

在深圳湾西北部海域进行表层沉积物取样,通过粒度分析获取沉积物粒度参数。结果表明,该海域中北部沉积物以粉砂为主,分选较差;局部有较粗的砂、砾沉积物分布,分选性差。地质统计分析结果显示,粒度参数半方差—距离的相关性与沉积物粒度参数的空间分布有关,剔除空间"异常"值后,可在半方差图中获取粒度参数的变程值,并将其作为粒径趋势模型的特征距离。粒径趋势分析表明,海湾西部海域的沉积物向东北净输运,深圳河口海域的沉积物偏西向输运,从而在海湾北部近岸海域形成一个沉积物汇聚中心,这与水动力观测结果基本吻合。此外,210Pb测年结果也表明,这个沉积物汇聚中心的沉积速率也相应较高,显示出较强的淤积趋势。

Surface sediment samples were collected in the northwestern Shenzhen Bay, China, and then analyzed using by Mastersize 2000 and sieving to obtain grain size data. The results indicate that the silt sediment covers the North Bay with little poorly sorting and poorly sorted coarse sand and gravel in some areas. In order to use the grain size trends analysis model, the geostatistic method is used for the determination of characteristic distance. The geostatistic results are associated with the some ＂normal＂ or ＂abnormal＂ grain-size parameters in the study area. A variation range is remarkably determined after eliminating some ＂abnormal＂ values, which could be considered as the characteristic distance. The grain size trends analysis shows that sediment transport northeastwards in the west bay, and westwards in the Shenzhen River estuary area. Thus, the near shore area adjoining the north coast becomes a net sediment transport converge area. This pattern is highly consistent with the local hydrodynamics. Furthermore,210Pb dating result suggests that the sedimentation rate in this area is much higher than other area in the bay, which is consistent with the results of grain size trends analysis.