青海湖沉积物中微量元素纵向分布反映的古环境意义

Paleoenvironmental records from the vertical distribution of trace elements in the sediments of Qinghai Lake

通过对青海湖QH1岩心沉积物中微量元素Li,V,Cs,Co,REE(La,Ce,Pr,Nd,Sm,Eu,Gd,Tb,Dy,Er,Yb)及叫ωCs/ωRb的高分辨率分析,结果表明:微量元素在沉积物中的质量分数变化与沉积环境密切相关,在温暖湿润的气候环境下,沉积物中ωΣREE,ωLi,ωV,ωCs,ωCo较高、ωCs/ωRb较大;而在冷干的气候环境条件下,元素质量分数相对较低.∑REE(稀土总量)与ωCs/ωRb之间呈良好的正相关性,ΣREE可以作为反映青海湖环境的一个有效指标.近8500年来湖区气候环境变化特征表现为冷干与暖湿的交替,气候的突变在沉积物上表现为元素质量分数的突变.

Based on high-resolution analyses of trace elements of Li, V, Cs, Co, REE(La, Ce, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Er, Yb) concentrations and ωcs/ωRb in sediments of Qinghai Lake, it can be concluded that the sediments from Qinghai Lake have very similar REE distribution patterns, which are moderately rich in light rare earth element(LREE). Indicating that the sediments at different depths have the same (or the similar) source supply and formation process. Trace elements content of lake core are changed with environmental change. There is a well positive correlation between Σ contents and ωcs/ωRb which has obviously environmental significance for indicating climatic and environmental changes. Σ, Li, V, Cs, Co concentrations and ωcs/ωRb are all relatively high, This indicates the warm and humid climate, while the lower contents of chemical elements are corresponded with the cold and arid climate condition. The characteristic of climatic and environmental change was the replacement between cold-arid and warm-humid in recent 8500 years, the sudden change of elemental contents was in accordance with the transformation of climate. Therefore, Σ in sediments of Qinghai Lake is an effective indicator to reflect the paleoclimatic and paleoenvironmental variation in the high-cold semi-arid areas.