广东近岸海湾表层沉积物的稀土元素特征及其物源示踪

Characteristics of rare earth elements in the surface sediments from the bays along the coast of Guangdong Province and their source tracers

本文对广东省近岸10个典型海湾的表层沉积物进行了系统的稀土元素(rare earth elements,REE)测试和分析,以期发现沉积物的物源组成特征及其控制因素。研究结果表明,同一海湾内沉积物的稀土丰度差异不明显,但不同海湾之间具有一定的差别(133.58—251.77mg.kg 1)。球粒陨石标准化配分曲线表现出轻稀土(La到Eu)富集、重稀土(Gd到Lu)亏损、δEu负异常等典型的陆源沉积物特征;PAAS(Post-Archean Australian Shale)标准化配分模式显示出明显的中稀土(Sm到Ho)富集特征,与已报道的国内河流沉积物REE特征相似。海湾沉积物与入海河流沉积物及流域内的原岩组成特征的比较说明,后者对海湾沉积物的控制作用明显。REE配分曲线的一致性和中稀土富集特征表明海湾沉积物主要来自汇入海湾的山溪及河流输入的沉积物。

A systematic study of rare earth elements（REE） within the surface sediments from 10 bays situated along the coast of Guangdong Provence,China,has facilitated a more rigorous understanding of constraints on sediment provenance in the area.The results show that REE concentrations are similar within a single bay,but vary considerably（133.58–251.77 mg.kg 1） among the bays.The chondrite-normalized distribution patterns show the typical enrichment of light REEs（La to Eu） relative to heavy REEs（Gd to Lu）,and an apparent depletion of Eu,which is diagnostic of a terrigenous sediment source.Obvious enrichments of the middle REEs（Sm to Ho） in the PAAS-normalized（Post-Archean Australian Shale）distribution patterns of these bay sediments are similar to results reported from large rivers in China.Comparing the REE composition of the bay sediments with those of adjoining fluvial sediments and with the bedrock of the surrounding drainage basins,the bedrock of the surrounding drainage basins are indicated as the dominant sediment source.The uniform REE distribution patterns and MREE enrichments confirm that the sediments are derived from the material transported by the streams and rivers that discharge into the bays.