南海中部晚更新世以来沉积物常量元素组分含量分布特征及其影响因素  

Distribution characters of major elemental composition contents and the influence factors in sediments of the late Pleistocene in central South China Sea

作　　者：汪卫国[1] 陈坚[1] 

机构地区：[1]国家海洋局第三海洋研究所,福建厦门361005

出　　处：《台湾海峡》2011年第4期449-457,共9页Journal of Oceanography In Taiwan Strait

基　　金：国家自然科学基金资助项目(40976037);国家海洋局第三海洋研究所基本科研业务费专项资金资助项目(海三科2007012)

摘　　要：为研究南海中部沉积物中常量元素组分含量的分布特征及其影响因素,对南海中部中沙以南陆坡—深海盆区的表层沉积物和2根柱状样进行了SiO2、Al2 O3、Fe2 O3、TiO2、K2 O、MnO、P2 O5、CaCO3等常量元素组分及生物硅(BSi)含量的分析.结果显示,南海中部表层沉积物中SiO2、Al2 O3、Fe2 O3、TiO2、K2 O等与陆源碎屑矿物有关的常量元素组分含量的变化主要受生源CaCO3含量的控制,而CaCO3的含量,则受水深的控制.CaCO3含量与水深的关系表明,研究区CaCO3临界补偿深度约为3 800 m.受底层洋流的控制,研究区海山附近硅质生物碎屑局部富集,并稀释其他元素含量.研究区表层沉积物中的MnO和P2O5含量的分布规律不同于其他常量元素组分,其中,Mn可能部分交代CaCO3中的Ca,P2O5部分可能为海底超基性岩海解来源的.2根柱样的地球化学变化特征显示,晚更新世以来,南海中部CaCO3临界补偿深度以浅海底沉积物中除Mn和P以外的其他各常量元素含量受生源CaCO3含量的影响,而在CaCO3临界补偿深度以深的海域,则受BSi含量的影响.南海中部沉积物柱样中的CaCO3和BSi含量变化与全球变化有关,可作为古气候环境变化研究的代用指标.The major elemental compositions,including SiO2,Al2O3,Fe2O3,TiO2,K2O,MnO,P2O5,CaCO3 and biogenic Silica(BSi),of surface sediments and 2 cores of the Late Pleistocene obtained from central South China Sea(SCS) were analyzed with an attempt to understand the major element variations and its mechanisms related to global changes.The results showed that the content of major elemental composition in surface sediments,such as SiO2,Al2O3,Fe2O3,TiO2,K2O,which mainly from terrigenous minerals were under the influence of biogenic CaCO3,and the content of CaCO3 in surface sediments was controlled by water depth.The relationship between CaCO3 content and water depth indicated that the carbonate critical depth(CCrD) is about 3 800 m in central CSC.BSi content was abnormally high near the sea mount resulted from bottom current,which deluted the contents of other elemental compositions.The variations of MnO and P2O5 in surface sediments were different from other compositions.Part of Mn might replace the Ca of biogenic CaCO3.P2O5 in sediments might have originated mainly from hydrolytic decomposition of ultrabasic rocks.The variations of major elemental compositions,except for Mn and P,indicated that sediments above the CCrD were under the influence of biogenic CaCO3,otherwise,the BSi,when they were below the CCrD during the Late Pleistocene in the study area.The changes of most major elemental compositions during the Late Pleistocene were responded to global changes,especially the biogenic CaCO3 and BSi,suggesting that the sediments from deep basin of central SCS have recorded the global changes.

关 键 词：海洋化学 南海中部 晚更新世 沉积物 常量元素 影响因素 

分 类 号：P734[天文地球—海洋化学]