珠江三角洲平原区第四纪沉积物地球化学特征及其控制因素

Element geochemical characteristics and controlling factors of the Quaternary Sediments in the Pearl River Delta plain

在珠江三角洲经济区多目标区域地球化学调查基础上,根据珠江三角洲第四纪地质、基底地形、水系走向等方面的资料,在珠江三角洲布署了6条钻孔剖面,共44个第四纪地质钻探,对其晚更新世以来沉积物的地球化学特征进行了系统分析。结果表明:珠江三角洲平原区重金属元素富集,特别是以Cd、Hg、Cu、Pb、Zn、Ni、As为代表的重金属元素较为富集,形成高背景区。不同区域富集元素类型及富集程度呈现较大差异,其中以西北江三角洲各元素最为富集,而潭江三角洲仅U、Al2O3富集,其Cl、Cd、Cu、Sb、Ca O等元素含量明显低于全区平均含量,东江三角洲Mo、S、Th、Tl、U等元素富集,Cd、Cl、Co、Cr、Hg、Mn、Ni、Sb、Sr、Ti、V、Mg O、Ca O、Na2O等元素含量明显低于全区平均含量。元素空间分布差异的控制因素是三角洲平原物质来源差异及沉积体系变迁。

Based on multi-purpose regional geochemical survey in Pearl River Delta Economic Zone, quaternarysediments of 44 cores were emplaced in the Pearl River delta plain. Totally 39 elements and indicators for soilsand sediments were determined. According to the characteristics of this area, we firstly carried out the study ofgeochemical characteristic of delta formation evolution. The results indicate that the average concentrations ofmost elements in sediment were significantly enriched, the heavy metal elements Cd、Hg、Cu、Pb、Zn、Ni、As haveaccumulated remarkably, especially. Element type and enrichment degree are distinguishing in different area ofthe Pearl River delta pain. The main enrichment areas are West River and North River alluvial, Tan River andEast River alluvial are the background area; the main factors that control the element contents of sediments in thisarea are the source material and the change of sedimentary environment.