中文摘要：

对位于渤海湾岛屿区的砣矶岛中部大口北黄土剖面的粒度特征分析表明：1）大口北黄土剖面粉砂粒级含量最高,砂粒粒级次之,黏土含量最低,总体粒径比较粗,与岛屿区其他黄土相比呈现明显的规律性。荒漠化的渤海湾陆架近物源应是其主要原因;2）根据沉积物粒度组成和粒度频率分布曲线特征,并运用萨胡判别公式对其沉积环境进行判别,可判知大口北黄土沉积为风成沉积;3）根据中值粒径（Md）、环境敏感粒级（〉80μm和5~10μm）、砂粒百分含量和黏粒百分含量等指标,并结合实际的野外观察,将该剖面划分现代耕作层、黄土层和古土壤层,记录了剖面形成以来区域古气候环境及渤海湾海平面变化的历史过程。

英文摘要：

Loess deposits are widely distributed over the northern China. The study region is located in the central islands in the Bohai Gulf and neighboring regions of of The Miaodao Group islands. Samples from the Dak- oubei loess section in Tuoji islands, Shandong Province were employed here for the grain - size and sedimentary analyses. Results indicate： （1） the loess grain size distribution of the section is dominated mainly by silt, and the contents of fine clay are lower and sand is higher. （2） According to Sahu~ discrimination formula and the characters of both the grain size composition and distribution curves, it is found that the main sedimentary depos- its are formed in Aeolian environment. （3） The section is divided into modern soil layer, two loess layers and paleosol layers, they record the information of climatic change and sea level variations in Bohai Gulf.