山东半岛近海不同粉砂粒级含量分布的空间差异性及其沉积学意义

粉砂是现代陆架和河口沉积物最主要的粒级组分,但由于其复杂的沉积动力学行为,我们对于不同粉砂粒级的沉积学特征和行为并没有完全掌握。本文分析了山东半岛近海表层沉积物中不同粉砂粒级组分含量的空间分布特征,探讨了其控制因素。结果表明,山东半岛周边近海沉积物类型以泥质沉积为主,但不同粉砂粒级组分具有明显的空间分布差异性。极细粉砂、细粉砂与黏土组分的含量变化一致,表明了其相似的沉积动力学行为。粗粉砂组分的含量空间变化最大,在山东半岛的北部泥质条带、东部“泥楔”和南部近岸具有明显的高含量,其含量与其他各粉砂组分具有明显的负相关性。从表层沉积物的粒度组分与分布规律,可以证明研究区表层沉积物主要以黄河携带物质为主,但流入本区的一些中小型河流也明显提供了部分物源,只是其提供物质的扩散范围有限。结合水动力分析和物理海洋学等方面的认识,我们认为造成不同粉砂组分空间分布差异性的原因主要受物源、区域水动力学条件、局部地形（底形）等因素控制。另外,还发现了山东半岛“泥楔”沉积物的粗粉砂组分含量偏高、现代沉积速率也偏大,这些现象在空间上与“海洋锋面”位置一致,对于海洋锋面的沉积学意义还需要进一步的调查研究和数值模拟工作。

Spatial variability of different silt components and its sedimentary significance offshore Shandong Peninsula

To achieve a more robust understanding of the transport pattern of silt components in offshore areas, the grain size characteristics of 783 surface samples of fine-grained sediments are used to interpret the sediment transport pathways and predominant sedimentological conditions offshore the Shandong Peninsula, Yellow Sea. Based on the variation in the grain size composition, a regional "silt fractionation" was observed, and the very fine silt (VFSt) and the fine silt (FSt) displayed similar dynamic behaviors to that of the clay fraction during transportation and deposition, and these silts all acted as flocs. By contrast, the coarse silt (CSt) was primarily transported and deposited as single grains, indicating that the CSt content was the environmentally sensitive component in the sediments in the study area. The sediments displayed complicated sources based on the grain size analysis. In the northern part of the study area, the fine-grained sediment primarily originated from the Huanghe River Estuary (suspended or reworked, whereas in the eastern Shandong Peninsula, the sediments of the mud wedge were primarily composed of Huanghe-derived sediments and characterized by CSt-enriched, and in the southern Shandong Peninsula, the sediments primarily originated from the small rivers nearby. The marine fronts in the study area were thought to be the major factor controlling the settling and deposition of coarse silt. Further study should be carried out on the mechanisms that the fronts control the deposition of silty fractions in shelf settings.