Grain-Size Characteristics and Its Geological Significance in the East China Sea Sand Ridges Area

东海典型沙脊区域沉积物的粒度和输运特征的研究仍比较缺乏。根据2022年和2024年的沉积物采样和测试资料，对研究区沉积物粒度特征及其沉积环境、输运趋势等地质意义进行分析讨论。结果表明，峰脊区沉积物比槽洼区稍粗，沉积物向上粗化，分选性变好。研究区沉积物有一个突出的细砂组份，但也含有多种粒级大小的细颗粒粉砂和粘土物质，沉积环境比较复杂，很可能是一种多源和多期沉积，主体是低海面时期滨岸浅海沉积，受到后期改造和/或现代悬浮细粒物质的混杂。研究区表层沉积物总体上呈现向东南外海输运的趋势。Studies on the grain size and transport characteristics of sediments in the typical sand ridge area of the East China Sea are still relatively lacking. Based on the sediment grain size test data in 2022 and 2024, the sediment grain size characteristics, sedimentary environment, transport trend and other geological significance of the study area were analyzed and discussed. The results show that the sediments in the peak ridge area are slightly coarser than those in the trough depression area, and the sediments coarsen upward and become better sorted. The sediments in the study area have a prominent fine sand component, but also contain a variety of fine-grained silt and clay materials of various grain sizes. The depositional environment is relatively complex, and it is likely to be a multi-source and multi-phase deposition, with the main body being a coastal shallow marine deposition during the low-surface period, which was subjected to later modification and/or mixing by modern suspended fine-grained materials. The surface sediments in the study area show a general trend of transport to the south-east offshore.