【作者】 徐刚；

【导师】 李安龙； 刘健；

【作者基本信息】 中国海洋大学 ， 海洋地质， 2010， 硕士

【摘要】 本文研究区域位于我国南黄海西部海域,地理坐标为33.5°-36°N,119°-122°E。探讨研究区内沉积物沉积特征和物质来源,对认识陆架区现代沉积动力过程及评价河流对海洋的作用具有重要意义。因此,本文对研究区海底表层沉积物样品进行了粒度、粘土矿物和元素地球化学等方面的测试与分析,并结合以上各种指标对研究区的沉积环境、沉积作用和物源进行了探讨。利用激光粒度仪对研究区486个海底表层沉积物样品进行了粒度测试。结果表明,按照Folk(1970)分类,区内沉积物类型为砾石、粉砂、砂质粉砂、粉砂质砂和泥,局部海区出现砂、砂质泥,其中砂质粉砂和粉砂质砂为区内分布最广泛的沉积物类型。研究区沉积环境及沉积物物源是控制研究海区表层沉积物粒度特征的主要因素。对研究区486个表层沉积物样品进行了常量元素和微量元素的化学测试和分析。结果表明,表层沉积物中许多元素在表生地球化学环境中具有相似的地球化学行为,基本上都遵循“元素粒度控制规律”。主要元素Al、Ti、Fe、Mg与大多数元素相关性高,说明其物质来源具有统一性。在微量元素中,Li、V、Cr、Co、Ni、Zn元素之间表现出明显的线性关系,说明它们具有相似的地球化学行为。稀土元素配分模式上,球粒陨石标准化曲线明显右倾,轻稀土元素相对富集,反映出沉积物中等程度的Eu负异常。北美页岩和上陆壳配分曲线均近于平坦,在曲线上未见明显的Eu异常,Ce异常也不明显。在研究区选取了482个表层沉积物样品,利用X射线衍射仪进行了粘土矿物分析。分析结果表明,研究区的粘土矿物组合类型主要为伊利石-蒙皂石-绿泥石-高岭石,组合类型与黄河粘土矿物组合类型相同。利用研究区几个典型的柱状样,对研究区的浅表层沉积特征进行了分析探讨。结果表明,海州湾外的钙质结核砾石形成于晚更新世,在全新世海侵时期被侵蚀而裸露于海底,后期因水动力的改造而混入了新的物质。研究区的粉砂质砂和砂的粒度参数具有滨岸高能带的特征,为全新世初期滨海环境下形成的。1128-1855年黄河从苏北入海,在苏北形成了规模宏大的老黄河水下三角洲,其中一部分覆盖在全新世海侵时期形成的残留砂之上。通过有限的资料分析,本文推断研究区东北部的砂质粉砂为山东半岛水下楔形体的末端沉积体,厚度仅有25Cm左右的砂质粉砂覆盖在全新世初期形成的残留砂之上。本文最后利用粘土矿物物源指示作用、元素比值、稀土元素球粒陨石标准化曲线、逐步判别分析、判别函数以及碳酸盐的物源指示作用,对南黄海西部陆架区表层沉积物的物质来源进行了探讨,结果表明南黄海西部陆架区的主要物质来源为黄河输送的物质。一是由黄海沿岸流携带而来的现代黄河物质；二是苏北老黄河口堆积体受侵蚀再搬运而来的物质,这两种物质均与黄河有关。另外研究区东北部和连云港近岸海域物质可能还会受到其近岸侵蚀基岩物质以及邻近海域的侵蚀基岩物质的影响。更多还原

【Abstract】 The study area is located in the western South Yellow Sea (33.5°-36°N, 119°-122°E). It is of great significance for understanding the dynamics of modern sedimention process of the coastal zone and the river effect on offshore sedimention as well as the sediment provenance. Using the data of grain-size distribution, clay mineral compostion and mayor and trace elements characteristics of the surface sediments samples colleted from the area, This paper discuss the sedimentary environments, sedimentation processes and sedimentary sources in the study area.Grain size analysis of the 486 surficial samples from the study area is carried out using the laser grain size analyser. According to Fork’s classification(1970), sediments in this area could be divided into gravel, silty sand, sandy silt, silt, sandy mud, mud, with silty sand and sandy silt as the major. The sedimentary environment and the sedimentary sources are the major factor that dominate the characteristics of the surface sediments in the study area.Chemical analysis is made for the major elements and trace elements of the surficial samples from the study area.The results show that most of the elements have similar chemical behavior in the hypergene environment. They generally comply with the rule which the grain size dominates the distribution of the elements. Major elements Ti, Fe, Mg and Al are correlated positively with many elements, which show that they have same provenance. Trace elements Li, V, Cr, Co, Ni, Zn exhibit notable positive correlation between each other, which show that they have same chemical behavior. In REE distribution patterns, the chondrite-normalized REE partition curve incline to the right, indicate that they are enriched in LREE and middle degree Eu negative abnormity. The North American shale and upper continental crust normalized REE partition curve both of even type, indicate no negative Eu and Ce anomaly.X-ray diffraction analysis is made for 482 clay mineral samples selected from surficial sediments. The results show that the clay minerals combination style mostly is illite-smectite-chlorite-kaolinite. The style is same with the Yellow River’s.This paper analyzes the shallow sedimentary characteristics by many typical downcores that recovered from the the study area. The outcomes show that the calcretes have formed in the late Pleistocene, and have exposed in the sea floor by the sea water erosion in the eary Holocene. The silty sand and sand have offshore characteristic in the study area, and they have formed in the offshore hypergene environments of Holocene. The Yellow River injected into Yellow Sea through the northern Jiangsu Province in the 1128-1855, and formed a tremendous old subaqueous Yellow River delta. Some of the delta covered the relicts which have formed in the transgression of the Holocene. This paper deduce the sandy silt in the north-east is distal sediments of the subaqueous clinoform arround the Eastern Shandong Peninsula by the limited datum. And it also covered the relicts which have formed in the transgression of the Holocene.In the last, this paper analyze the sediments sources of the weastern South Yellow Sea by clay minerals, ratios of elements, the chondrite-normalized REE partition curve, stepwise discriminant analysis, discriminant function and carbonate. The conclusion indicate that the surfacial sediments are from Yellow River in the study area. One is from the mordern Yellow River which is tansported by the Yellow Sea Current. the other cames from the Old Yellow River Delta. Moreover, the sediments resulting from the erosion of Shandong Peninsula,adjacent area bedrock and Lianyungang by sea water also contribute to the north-east and the Lianyungang sediments respectively.更多还原