【作者】 郑凯清；

【导师】 方念乔； 刘坚；

【作者基本信息】 中国地质大学(北京) ， 地质工程， 2012， 硕士

【摘要】 南海是西太平洋最大的边缘海之一，南海独特的地理位置和复杂的构造背景决定了南海的沉积特征具有鲜明的区域性特点，沉积物来源丰富且多样。本文通过建立和完善稀土元素（REE）的电感耦合等离子体质谱（ICP-MS）分析方法，在对南海西沙海槽HX132柱状沉积物开展稀土元素化学分析的基础上，利用稀土元素的特征参数，结合氧同位素地层学资料及部分常微量元素和粒度分析结果，对其基本分布特征及沉积环境意义进行了重点探讨。本文首先在海洋沉积物国家标准方法的基础上，简化样品前处理程序，利用ICP-MS法灵敏度高、检出限低、多稀土元素同时快速分析的优势，测定样品中的稀土元素。分析过程中采用国家一级标准物质监控及进行重复样检查，使分析方法的准确度、精密度满足要求，保证测定结果的准确可靠。HX132柱状沉积物取自我国南海北部西沙海槽区南部斜坡处，水深1526m，柱长11.33m。稀土元素总量（∑REE）总体不高，变化范围较大，平均含量为136.32×10^-6，轻重稀土比值（LREE/HREE）为7.25；具有一定程度的Eu负异常，δEu为0.83，Ce异常情况则不明显，δCe为0.94；∑REE与SiO₂的含量呈高度正相关而与CaCO₃、Sr的含量呈高度负相关；稀土元素球粒陨石标准化曲线为向右倾斜，显示轻稀土富集的分布模式。通过与具代表性海域表层沉积物进行对比，发现HX132沉积物在稀土元素含量和分布特征上与中国大陆架沉积物、南海细粒沉积物较为接近，主要以陆源沉积为主，有部分生源物质成分的加入，而火山源物质成分较少。HX132沉积物稀土元素的垂向变化特征显示，稀土元素含量主要受陆源碎屑矿物输入量的影响，冰期内由于大量陆源碎屑进入海域，导致∑REE升高；间冰期内陆源物质多被截留于大陆架上，对海槽的输入量明显减少，∑REE也随之减少。这一特征反映了稀土元素随冰川性海平面变化而产生周期性的波动。更多还原

【Abstract】 South China sea is the biggest marginal sea in the west Pacific, with the uniquegeographical location and complicated structure background, the South China Sea hasthe depositional characters of a distinct regional characteristics, with richness anddiversity of its sediment source material. This article have to establish the inductivelycoupled plasma mass spectrometry （ICP-MS） analysis method of rare earth elements（REE）, base on the chemical analysis of rare earth elements of HX132columnarsediments in xisha trough of South China Sea, combined with the results of traceelements and grading analysis and the data of oxygen isotopes stratigraphy, thedistribution characteristics and sedimentary environment significance are discussed.Based on the National Standard method of marine sediments, In this paper, to simplifysample preparation program, using the advantages of ICP-MS method of highsensitivity, low detection limit, and quick analysis of rare earth elements, to determinethe rare earth elements of the samples. In the course of analysis using the nationallevel standard material monitoring and repeated sample check, to make the analysismethod of accuracy, and the precision meet the demands, ensure the determinationresults are correct and reliable.HX132columnar sediments with length of11.33m is toke from the south slope areaof water depth of1526m in xisha trough of northern South China Sea. The totalamount of rare earth elements （∑REE） is not high, change range is very large,average content is136.32×10^-6, weight ratio of rare earth （LREE/HREE） is7.25;With a certain degree of Eu negative abnormal, δEu is0.83, Ce is not apparent ofabnormal, δCe is0.94;∑REE and SiO₂is highly relevant and CaCO₃, Sr is with highnegative correlation; The chondritic standardization curve of rare earth elements tilt tothe right, display distribution patterns of light rare earth enrichment.Through the contrast with the representative of surface sediment in continental shelf,the content and distribution characteristics of rare earth elements of HX132sedimentsare similar to the sediments of South China Sea and fine grained sediments of SouthChina Sea, is mainly terrestrial deposition with some other material, and less ofvolcano source material.The vertical variation of rare earth elements of HX132sediments shows, the contentof rare earth elements is influenced mainly by the input of the terrigenous minerals,because of clastic into the sea within the ice age, and it leads to increased∑REE; Ininterglacial stage, material was trapped in the continental shelf and the input to thetrough was significantly reduced,∑REE also decrease. The characteristics reflect thatthe rare earth elements produce periodic fluctuations while glacier sea level changes.更多还原