The Paleo-Environmental Significance of Sr and Ca Contained in Acid-Soluble Fraction of Plateau Loess Deposits in Xining Basin  

作　　者：谭红兵 马海州 鹿化煜 张西营 魏海珍 

机构地区：[1]Qinghai Institute of Salt Lakes,Chinese Academy of Sciences [2]Institute of Earth Environment,Chinese Academy of Sciences

出　　处：《Chinese Journal Of Geochemistry》2003年第2期156-163,共8页中国地球化学学报

基　　金：GrantedbyNationalNaturalScienceFoundationofChina (No .499610 0 6) ;KeyProjectofKnowledgeInnovation,ChineseAcad emyofSciences (KZCX1 10 0 1)

摘　　要：The Xining Basin, located on northeastern Qinghai-Xizang Plateau, is adjacent to the Qaidam Basin and Gobi-desert. Therefore, thick, integrated deposits of loess or paleo-sol sequence were well developed. As is well known, there is much paleo-environmental information recorded in loess and paleo|sol. So if we deal with paleo-environmental index from different angles, especially from loess geochemistry, some important and detailed paleo-environmental evolutional information will be acquired. Based on this, the authors determined the contents of Sr and Ca contained in acid-soluble fraction from the bottom to the top of the Panzishan section. This section was obtained through making a well about 17 m in depth, including S-1 paleo-sol that was developed during the last interglacial period. According to the results, it is found that variations in contents of Sr and Ca are well correlated with conversion of loess and paleo-sol. In loess deposits, the contents of Sr and Ca are higher than those in paleo-sol deposits. It is known that loess was deposited under cold-dry climate conditions and paleo-sol was developed during warm-humid climate episodes. It is concluded that due to their mobile behaviors, under cold-dry climate conditions, Sr and Ca are stagnant during weak weathering, but under warm-humid climate conditions, Sr and Ca are easily leached and transported in aqueous solution. Therefore, they can be utilized as indicators of climate changes. Moreover, variations in contents of Sr and Ca are more sensitive than susceptibility. The mobile behaviors of Sr and Ca contained in acid-soluble fraction can serve as a new quantitative index to evaluate paleo-environmental changes on the plateau.The Xining Basin, located on northeastern Qinghai-Xizang Plateau, is adjacent to the Qaidam Basin and Gobi-desert. Therefore, thick, integrated deposits of loess or paleo-sol sequence were well developed. As is well known, there is much paleo-environmental information recorded in loess and paleo|sol. So if we deal with paleo-environmental index from different angles, especially from loess geochemistry, some important and detailed paleo-environmental evolutional information will be acquired. Based on this, the authors determined the contents of Sr and Ca contained in acid-soluble fraction from the bottom to the top of the Panzishan section. This section was obtained through making a well about 17 m in depth, including S-1 paleo-sol that was developed during the last interglacial period. According to the results, it is found that variations in contents of Sr and Ca are well correlated with conversion of loess and paleo-sol. In loess deposits, the contents of Sr and Ca are higher than those in paleo-sol deposits. It is known that loess was deposited under cold-dry climate conditions and paleo-sol was developed during warm-humid climate episodes. It is concluded that due to their mobile behaviors, under cold-dry climate conditions, Sr and Ca are stagnant during weak weathering, but under warm-humid climate conditions, Sr and Ca are easily leached and transported in aqueous solution. Therefore, they can be utilized as indicators of climate changes. Moreover, variations in contents of Sr and Ca are more sensitive than susceptibility. The mobile behaviors of Sr and Ca contained in acid-soluble fraction can serve as a new quantitative index to evaluate paleo-environmental changes on the plateau.

关 键 词：黄土沉积物 西宁盆地 地球化学 青海高原 西藏高原 古环境 

分 类 号：X142[环境科学与工程—环境科学]