南极普里兹湾沉积物稀土元素地球化学特征

利用中国第29次南极科学考察在南极普里兹湾获取的3个短柱样品,进行了稀土元素测试分析,探讨了普里兹湾海洋沉积物稀土元素特征、分布模式及其控制因素。结果表明,普里兹湾各站沉积物中稀土元素含量各异,但均具有与上陆壳、中山站变质岩相似的页岩标准化配分模式,整体表现为轻稀土富集型,说明其物源一致,具有明显的大陆地壳来源特征。结合沉积物粒度、化学元素、生源指标等分析其分布及富集规律,发现物源是控制研究区稀土元素组成的主要因素,同时生物作用会对稀土元素的含量产生稀释,但"粒度效应"在此并不明显。普里兹湾沉积物短柱稀土元素参数垂向变化,反映了百年尺度内物源输入、沉积环境的变化。各站δCe值普遍具有向下减小的趋势,反映了随深度增加沉积环境的氧化性逐渐减弱的特征。

Geochemical Characteristics of Rare Earth Elements in The Sediments of Prydz Bay,Antarctica

Based on three short sediment cores collected in Prydz Bay (Antarctica) during the 29th Chinese National Antarctic Research Expedition, the rare earth element (REE) contents, sediment grain sizes, and biogenic proxies were determined to discuss the pattern and controlling factors of the REE distribution. The results showed that the REEs of Prydz Bay sediments vary in content but have similar shale-normalized distribution patterns, i.e., rich in light REEs, to upper continental crust and metamorphic rocks from Zhongshan Station, indicating they have the same terrigenous provenance. Based on the sediment grain size, major elements, and biosourced proxies, it is suggested that sediment provenance is the major controlling factor behind REE composition. Moreover, biological action might dilute the REE concentration, making the grain-size effect invalid. The REE proxies in the sediment profile were almost stable with depth, reflecting similar terrigenous inputs and depositional environments on the century scale. In addition, the δCe values generally decreased downward, suggesting a gradual decreasing trend in oxidability within the sediment core.