辽东湾表层沉积物粒度分布特征及其地质意义

GRAIN-SIZE DISTRIBUTION OF SURFACE SEDIMENTS OF THE LIAODONG BAY,BOHAI AND SEDIMENTARY ENVIRONMENT RESTORATION

对辽东湾140个表层沉积物进行了粒度分析,探讨了辽东湾表层沉积物的粒度分布特征和沉积物类型的分布格局,结合该区沉积物物源和沉积动力环境,探讨了两者对辽东湾海域沉积过程的控制作用。结果表明,研究区表层沉积物类型以砂质粉砂、砂质泥和泥质砂为主。研究区表层沉积物平均粒径变化范围较大(-0.06～7.42Φ),大多数站位集中在4～6Φ,平均粒径有两侧向中部逐渐变细的趋势。整体上,辽东湾东侧表层沉积物粒度比西侧粗,砂含量明显增加。研究区沉积物主要来源于沿岸河流携带的入海泥沙,而潮流和沿岸流对沉积物的分布起到控制作用。根据沉积物底质类型、物源及区域水动力强弱,将研究区划分为湾顶泥质、西岸砂质、渤海泥质、辽东浅滩砂质以及残留过渡沉积等5个沉积区。

A total of 140 surface sediment samples were collected from the Liaodong Bay for investigation of grain size distribution pattern in this study.Grain size parameters are calculated and the sediment types classified.Results show that the surface sediments of Liaodong Bay are characterized by sandy silt（sZ）,sandy mud（sM） and muddy sand（mS）.The mean grain size varies from-0.06 to 7.42 Φ,with an average value of 4.92 Φ.The surface sediments of the eastern Liaodong Bay were generally coarser than those in the western part,as the sand content increases eastward.The sediments delivered by rivers around the Liaodong Bay are the major sediment source,while the dispersal of sediment is mainly controlled by the combined effects of tidal and currents systems.According to sediment types,sources and hydrodynamic conditions,the study area can be divided into five depositional areas： the mud deposits in the northern Liaodong Bay,the sandy deposits in the western Liaodong Bay,the mud deposits in the southwestern Liaodong Bay,the sandy deposits in the Liaodong shoal and the relict deposits in the central part of the Liaodong Bay.