渤海及邻近海区表层沉积物粒度组成及沉积分区

通过渤海及邻域海区表层沉积物粒度实测数据,采用Folk三角图解分类方法,对比已有Shepard分类沉积物类型图对近岸的沉积物类型进行相应补充,编制沉积物类型图,并进行沉积分区。沉积物类型主要为砂质粉砂、粉砂质砂、砂质泥、泥质砂、粉砂和砂。根据沉积物类型分布特征、海洋环流、地形地貌及物质来源(入海河流物质影响程度),划分为4个沉积区,分别是辽东湾混合沉积区、渤海湾-莱州湾及周边泥质沉积区、老铁山水道-辽东-渤中浅滩砂质沉积区和北黄海西部泥质沉积区。渤海表层沉积物的分布受控于近源河流物质和海洋环流变化。渤海的潮流场控制泥沙输运,弱潮流区对应细颗粒沉积物沉降,强潮流控制区发育粗粒级潮流沙脊和沙席沉积。

GRAIN SIZE COMPOSITION AND DISTRIBUTION PATTRN OF SEAFLOOR SEDIMENTS IN BOHAI BAY AND ADJACENT AREAS

Based on the measured grain size data of the seafloor sediments taken from the Bohai sea and its adjacent areas, a sediment distribution map is compiled upon Folk's nomenclature system. Some part of the map is modified from the existing maps based on Shepard's classification. Sediments of sandy silt, silty sand, sandy mud, muddy sand, silt and sand are found in the studying area and the depositional characteristics are discussed. According to the integration of sediment distribution, oceanic circulation, bottom topography and sediment provenance (river flux influence), four depositional zones are classified, i.e. the Liaodong mixed depositional zone, the Bohai Bay-Laizhou Bay muddy depositional zone, the Laotieshan Channel-Liaodong-Bozhong sandy depositional zone, and northern Yellow Sea muddy depositional zone. The sediment distribution in the Bohai Sea is obviously dominated by the clastic sediments from rivers and oceanic circulation. The tidal current is the main factor which controls the sediment transportation and differentiation. Muddy sediments settle in weak tide areas while sand ridge and sheet deposits form in strong tide areas.