中文摘要：

现代黄河三角洲南部的废弃三角洲位于现行黄河亚三角洲和莱州湾南岸平原之间，其潮间带发育有宽平的不含砾淤泥质滩涂。在对南部废弃三角洲及附近岸段潮滩野外考察基础上，系统采集潮滩表层沉积样品进行粒度测试、分析，并与前人发表的该地区潮滩表层沉积粒度资料比较，讨论了20世纪80年代以来黄河人海泥沙减少背景下潮滩动力沉积特征演变。结果显示，南部废弃三角洲潮滩表层粒度特征及不同粒度参数之间关系与黄河现行亚三角洲具有显著差异，其细粒粘质组分和粗粒砂质组分分别来自不同的动力沉积过程，细粒组分主要沉积于河口行水时期的三角洲潮间滩涂，而粗粒组分系废弃后潮滩经现代沉积动力过程改造而成。在黄河泥沙显著减少背景下，通过潮滩与莱州湾西南部潮下带水下岸坡横向泥沙交换，即潮滩原有细颗粒泥沙流失、潮下带部分粗颗粒泥沙进入潮滩，结果使得废弃三角洲潮滩表层沉积发生了显著粗化，主要表现为粘土含量减少和粘／泥比减小，并在2007～2013年间发生了从粘性砂向非粘性砂的转变。正是由于潮滩的粗化，使得南部废弃三角洲潮滩宽度、位置在其遭到废弃以来的数十年中保持基本稳定，但其表层沉积近期由粘性砂向非粘性砂的转变，必然会使未来潮滩地貌冲淤演变出现新的特点。

英文摘要：

The modern Yellow River mouth and the Yellow River delta has developed since the Yellow River began to pour into the Bohai Sea again in 1855. Since then, the Yellow River estuary has migrated north-south frequently along the western coast of Bohai Bay. In landform evolution, a new river mouth sandspit and a sub-delta formed rapidly, and the abandoned sub-delta retreated synchronously in response to each estuary migration. As a result, the Yellow River delta, which constituted by many sub-deltas, has extended into the Bohai Sea continually in its evolution history. Thus the Laizhou Bay was cut out of the southern Bohai Bay as an independent bay. The southern abandoned Yellow River sub-delta （SAYS） mainly developed during the periods of 1934-1938 and 1947-1953 when the Yellow River flown into the Bohai Sea along the Tianshuigou channel which has abandoned for more than 60 years. The SAYS located between its two adjacent geomorphic units of the present Yellow River sub-delta （PYS） and the sedimentation plain along the southern Laizhou Bay （PSLB） , whose inter-tidal zone has developed wide fiat gravel-free muddy inter-tidal flats. A total of 238 surficial sediment samples along the inter-tidal fiats （including whole SAYS and its adjacent zones） were collected during ebb tide in the period of March 2013 to July 2014. Furthermore, 106 sample points are arranged along 10 inter-tidal flat transverse profiles, of which 8 profiles are located in SAYS and the other 2 are located in PSLB. The surficial fiat sediment samples were evaluated by grain size analysis and granularity parameter calculation. According to the granularity analysis results, the grain size frequency cumulative curves of each sample was drawn by the contents of grain size and clay, silt, sand and mud （clay plus silt）, as well as the ratio of clay/mud. The grain size parameters of mean grain size （ Mz） , sorting coefficient （ So） , skewness （SK） and kurtosis （Kg） were obtained via the Folk and Ward method. To analyze gra