【作者】 高志友；

【导师】 尹观； 朱赖民；

【作者基本信息】 成都理工大学 ， 地球化学， 2005， 博士

【摘要】 南海是西太平洋最大的边缘海之一，作为大陆与大洋的接合部和相互作用带，其独特的地理位置，复杂的构造环境，特殊的洋流作用，决定了其沉积环境的复杂性和沉积物质来源的丰富性和多样性。通过对南海表层沉积物微量元素、稀土元素、铅同位素地球化学特征及沉积物粒度分析的研究，对南海表层沉积物的地球化学特征和物质来源作了重点探讨，并结合南海现代沉积环境进行了地球化学分区，结论如下： （1）元素地球化学特征表明，元素丰度受沉积物粒度控制明显。除Sr以外，细粒级沉积物中元素含量明显高于粗粒级，变化幅度大。微量元素含量因物质来源和沉积环境不同而差异较大，并随地球化学性质的类似程度形成明显的元素组合区域分布，分别代表了不同的物源（陆源、生物源、火山源等）。绝大部分微量元素含量介于大陆物质与大洋物质之间，并靠近大陆物质，沉积物类型虽有向大洋沉积过渡的趋势，但仍表现出明显的“亲陆性”；特征元素对比值关系分析表明，南海沉积物的样品点投影与陆源端元物质接近，表明其物质来源以周缘大陆输入为主。 （2）稀土元素的平均丰度接近于中国黄土和福建花岗岩的丰度，而与太平洋沉积物中稀土元素的丰度相差较大，具有明显的“亲陆性”。球粒陨石标准化配分模式显示，陆架区稀土均表现为轻稀土富集、重稀土亏损，具明显铕负异常，表现为典型陆源沉积。南、北陆架区的稀土配分曲线有明显差异，分别代表了不同的物源输入。深部海盆区中稀土和重稀土比其他海区明显富集，稀土配分模式负铕异常相对平坦，反映生物沉积和幔源火山沉积物质对陆源物质有明显影响和改造。南部岛礁区稀土总量远低于其他海域，富集中稀土，且铈负异常非常明显，显示出生源沉积的特征。总体上，南海沉积物稀土特征参数和配分模式与长江、黄河、珠江等陆源河流以及东海、冲绳海槽等陆源海非常接近，明显偏向于陆源沉积类型。 （3）铅同位素组成及三维拓扑投影矢量V₁、V₂值示踪结果显示：东北部海域沉积物铅同位素组成与珠江、华南地体的铅同位素组成及V₁、V₂值范围一致，反映其物源主要是珠江以及经台湾海峡输入的华南陆源物质。西部海域铅同位素更多还原

【Abstract】 South China Sea is one of the biggest marginal seas of the West Pacific Ocean. As a copulae and interactional zone between the continent and ocean, South China Sea has special geographical location, complicated tectonic background and particularly ocean current movement, which come out the complicated sedimentary environment and diverse sediments provenances. By studying the geochemical characteristics of the trace elements, rare earth elements and lead isotope, granularity analysis together, the geochemical characteristics and provenances of the surface sediment in South China Sea were discussed with emphasis in this paper, and several deposit geochemical zones were distinguished, according to the modern sedimentary environment of the ocean. Main conclusions are summarized as follows:(1)The geochemical characteristics of the trace elements show that elements aboundence is obviously controlled by the grain size. Except strontium, the concentrations of elements in fine-grained sediment is great higher than those in coarse-grained, with a wide range of variations. Owing to different source and sedimentary environment, the element concentrations between samples are greatly different, which consequently result in distinct regional distributions of elements association, representing various supply sources respectively (terrigenous matter, biologic matter and volcanic materials). Most of trace elements have concentrations between that of continental matter and ocean matter but incline to continental matter, showing strong continental orientation. Ratios of some selected element showed on scatter plots clearly indicate the sediment samples of South China Sea are close to terrigenous matters, and its supply sourece are mainly from ambient continent.(2) The mean Σ REE of the sediment is close to Chinese loess and granites in Fujian province, far different from Pacific Ocean sediment, showing strong continental orientation too. The chondrite-normalized REE patterns exhibit that LREE are great richer than HREE in the sediments of the continental shelf, and there is remarkable minus-abnormity of europium, representing typical terrigenous components. The chondrite-normalized REE patterns of sediments in south continental shelf are different from those in North continental shelf because of having the different supply sources. Sediments in deep ocean basin evidently have richer MREE and HREE than those in other zones, and there have less minus-abnormity of europium, which reflect the biologic matter and volcanic materials greatly influenced the terrigenous matters in this area. Having MREE enrichment and evident minus-abnormity of cerium, the total REE in south coral reefs sediments is largely lower than that in other ocean zones, which indicate the dominately biologic sources of the sediment. But in total, the REE characteristics and normalized REE patterns of South China Sea sediment are very close to those of terrigenous river such as Yangtse更多还原