【作者】 程鹏；

【导师】 高抒；

【作者基本信息】 中国科学院海洋研究所 ， 海洋地质学， 2000， 博士

【摘要】 本文通过在北黄海西部海区进行的海洋地质与地球物理调查，获得了大量沉积物样品和实测数据。根据对沉积物样品的粒度、地球化学和粘土矿物分析，²¹⁰Pb沉积速率测定及ADCP数据处理，探讨了北黄海细颗粒沉积物的沉积特征和输运过程，并分析评价了激光粒度仪测试结果，探讨了ADCP测量悬沙浓度的可行性。 激光粒度仪具有良好的测量精度，其测量误差主要原因取决于测试样品的制备。与传统粒度分析方法（沉降法和筛析法）相比，激光粒度仪（Cilas 940L型）测定的沉积物平均粒径偏粗，分选偏差。测定的粘土组分含量约为沉降法的60％，其原因在于不同测试方法的原理和沉积物颗粒不规则的形状。因而，在分析、比较粒度数据时要保持在同一测量系统之内。 本区的细颗粒沉积物主要分布于北黄海中部和山东半岛沿岸、大连湾附近，粗颗粒沉积物则主要分布于庙岛群岛以东和大连湾东南侧海区。沉积物平均粒径、分选系数、偏态系数等粒度参数的分布有一定的对应性。除庙岛群岛东侧的砂质沉积分选较好之外，其它海区的沉积物总体特征是，粒径越粗，分选越差，偏态更正偏；而粒径越细，分选越好，偏态系数也较低。 粒度趋势显示山东半岛北侧的沉积物具有向东和向东北的输运趋势，同时整个区域显示出向北黄海中部汇聚的趋势。研究还表明粒度趋势分析方法在大范围的陆架区域具有较好的适用性。在操作中，使用规则的正方形网格可以较全面地判断、合成趋势矢量，进行高密度的采样有助于揭示沉积物净输运趋势的细节特征。应注意的是，粒度趋势矢量只代表沉积物净输运方向，而不能反映输运率的大小。 北黄海中部泥质沉积结构均匀，粒度变化在垂向上很小。泥质沉积的厚度自南向北逐渐减薄，整个泥区的面积约6250Km²，沉积速率1-2mm/yr，沉积通量为6-10×106t/yr。粘土矿物和地球化学特征表明中部泥质沉积为多源沉积，浅地层剖面和北黄海物质供应量的分析表明黄河物质是其主要物源。 根据理论分析和现场标定，ADCP具有测量悬沙浓度的潜力；通过对实测数据的分析，提出了深度标定方法，其测量悬沙浓度的精度可以满足沉积动力 学研究的需要． 4个定点观测站的余流和悬沙迢量的净输运方向为近东向，显示悬沙由渤 海输人北黄海．输运机制分析表明悬沙运动以平流输运和垂向环流输运为主。更多还原

【Abstract】 In order to reconstruct the depositional history of ancient epicontinental seas, it is important to understand sediment characteristics and transport processes of fine-grained sediment on modem continental shelf environments. A large number of seabed and suspended sediment samples, shallow seismic profiles and ADCP data were obtained during two cruises to the northern Yellow Sea. Based upon grain size, clay mineral and geochemistry analyses, and ADCP data processing, the fine-grained sediment characteristics and transport processes are discussed, and the performance of a Cilas 940L laser particle sizer is evaluated and compared with pipette and sieving methods. In addition, the feasibility and in-situ calibration of suspended sediment concentration measurements with ADCP are analyzed. The reproducibility of measurement on Cilas 940L appears to be satisfactory. Sample processing procedure is responsible for the magnitude of the error in the measurement. Cilas 940L give a lower fraction of clay particles (<84)) by 40 % on average than pipette data. The results obtained with the Cilas 940L show somewhat larger mean grain size and lower sorting coefficient than pipette/sieving results. Such differences may be attributed to the different principles of the methods (i.e. differences in the definition of grain size) and particle properties, especially non-sphericity shapes. Over the study area, fine-grained material is distributed mainly over the central northern Yellow Sea and near the coastline of Shandong Peninsula and Dalian Bay, whereas coarse- grained material is found to the east of Miaodao lsands and in the northwestern part of the area. Correlations between the grain size parameters are present. In general, except that the sand near Miaodao Isands is coarse grained and well sorted, the sediment with a large mean grain size is associated with a poorer sorting coefficient and higher positive skewness value, than a small size. Grain size trend analysis shows that sediments along the northern coast of Shangdong Peninsula are transported towards the east and northeast. Accumulation is taking place in the central area, as indicated by the convergence of the grain size trends. It is suggested that grain Ill size trend analysis is applicable to large-scale continental shelf areas. Sufficiently small sampling interval is necessary to delineate transport patterns in detail and a uniform (grid-iron) sampling grid is relatively good for assessing the direction of transport vectors. It should be noted that the sediment transport vector contains information on transport direction, rather than the magnitude of transport rate. ADCP has the potential to measure the suspended sediment concentration under the condition that the grain size distribution does no vary considerablly little during the survey period. An in-situ calibration formula has been developed and used to calculate the concentration profile. The results indicate that calibration with different depths can improve the measurement accuracy and meet the demand of sediment dynamics research. The deposit over the central part of the northern Yellow Sea is characterised by homogeneous mud, without large vertical variations in grain size. The thickness of the mud deposft decreases from the south to the north. The accretion rate is 1-2 mm/yr, which is equivalent to a vertical flux of 6-10 x lO6tlyr over the area of 6250 km2. The clay minerals and更多还原