青藏高原中部湖泊沉积物中Zr/Rb值及其环境意义  

VARIATION OF Zr/Rb RATIOS IN LACUSTRINE SEDIMENTS OF THE CENTRAL TIBETAN PLATEAU AND ITS ENVIRONMENT IMPLICATIONS

作　　者：陈诗越[1] 王苏民[1] 金章东[1] 沈吉[1] 

机构地区：[1]中国科学院南京地理与湖泊研究所

出　　处：《海洋地质与第四纪地质》2003年第4期35-38,共4页Marine Geology & Quaternary Geology

基　　金：国家重点基础研究发展规划项目(G1998040810)

摘　　要：由于青藏高原及其周边地区构造复杂,湖泊沉积物中的粒级差别很大,单一的测量方法往往难以奏效。Rb、Zr是表生地球化学过程中的稳定元素,但它们之间也存在显著差别,Rb一般富集在细颗粒中,Zr则在粗颗粒中含量较高。研究发现,湖泊沉积物中Zr/Rb比值与粘土(<2μm)含量存在显著相关,Zr/Rb值反映了湖泊沉积物的粒度大小。Zr/Rb比值所揭示的青藏高原中部280万年来经历的3次大的环境演化过程与岩性变化、孢粉指标反映的环境特征是一致的。In areas of the Tibetan Plateau and its margin, the tectonic movement can cause large variations of the sediment particle sizes. So it's difficult to use a single method to measure the sediment grain size. The two elements of Rb and Zr are immobile during the chemical weathering process,but there is a principal difference between them: Rb is enriched in finer grain sizes, while Zr is concentrated in coarser fractions. Chemical analysis of the lacustrine sediments from the Co Ngoin Lake, central Tibetan Plateau, shows that there is an excellent correlation between Zr/Rb ratios and grain size(<2 μm). Thus, Zr/Rb ratios can be used to indicate grain sizes variations. The sedimentary records of Zr/Rb ratios indicate that there are three strong environmental evolution processes in the last 28 MaBP from the Co Ngoin, central Tibetan Plateau, consistent with the sedimentological indications and the pollen record.

关 键 词：湖泊沉积物 Zr/Rb值 沉积物粒度 错鄂湖 青藏高原 

分 类 号：P595[天文地球—地球化学] P512.2[天文地球—地质学]