Speleothem Mg, Sr and Ba records during the MIS 5c-d, and implications for paleoclimate change in NE Sichuan, Central China  

作　　者：ZHOU HouYunt WANG Yue HUANG LiuYuan MAI ShangQuan 

机构地区：[1]School of Geography, South China Normal University, Guangzhou 510631, China [2]School of Geographical Science, Southwest University, Chongqing 400715, China

出　　处：《Chinese Science Bulletin》2011年第32期3445-3450,共6页

基　　金：supported by theNational Natural Science Foundation of China (40973009 and 40672120)

摘　　要：Trace metals of Mg, Sr and Ba in a stalagmite (SZ2) collected from Suozi Cave in NE Sichuan, Central China, were analyzed with ICP-AES. The stalagmite was dated to have developed between 120 and 103 ka BP. Results indicate that the Mg/Ca, Sr/Ca and Ba/Ca ratios of SZ2 varied between (9500-14700) 10 6 , (54-123) 10 6 and (31-82) 10 6 , respectively. The three records displayed significant millennial scale variations, which correlate with changes in past climate and environment. Lower values of Mg/Ca ratios and higher values of Sr/Ca and Ba/Ca ratios of SZ2 occurred during relatively cold-dry marine isotope stage (MIS) 5d, while the opposite trend was observed during relatively warm-humid MIS 5c. Trace metals in speleothems can be affected by distribution coefficients or trace metal concentrations in solutions from which speleothems precipitate. Temperature is suggested to be the dominant controller of Mg/Ca ratios in SZ2, whereas the Sr/Ca and Ba/Ca ratios may have been influenced by surface soil and atmospheric dust activities and prior calcite precipitation in Suozi Cave. Further investigations are warranted as to whether Sr/Ca and Ba/Ca ratios were affected by temperature and growth rate of the speleothem. The shifts of Mg/Ca, Sr/Ca and Ba/Ca records in SZ2 during the transition from MIS 5d to 5c apparently were earlier than the oxygen isotope record ( 18 O) of the same stalagmite. This possibly indicates (1) that atmospheric dust activity (the mechanism affecting SZ2 Sr/Ca and Ba/Ca ratios) is closely related to temperature, and (2) that temperature changes (dominated by solar insolation) precedes change in speleothem 18 O records which are controlled by both summer monsoons and winter temperatures.Trace metals of Mg, Sr and Ba in a stalagmite （SZ2） collected from Suozi Cave in NE Sichuan, Central China, were analyzed with ICP-AES. The stalagmite was dated to have developed between 120 and 103 ka BP. Results indicate that the Mg/Ca, Sr/Ca and Ba/Ca ratios of SZ2 varied between （9500-14700）x10-6, （54--123）x10-6 and （31-82）x10-6, respectively. The three records displayed significant millennial scale variations, which correlate with changes in past climate and environment. Lower values of Mg/Ca ratios and higher values of Sr/Ca and Ba/Ca ratios of SZ2 occurred during relatively cold-dry marine isotope stage （MIS） 5d, while the opposite trend was observed during relatively warm-humid MIS 5c. Trace metals in speleothems can be affected by distribution coefficients or trace metal concentrations in solutions from which speleothems precipitate. Temperature is suggested to be the dominant controller of Mg/Ca ratios in SZ2, whereas the Sr/Ca and Ba/Ca ratios may have been influenced by surface soil and atmospheric dust activities and prior calcite precipitation in Suozi Cave. Further investigations are warranted as to whether Sr/Ca and Ba/Ca ratios were affected by temperature and growth rate of the speleothem. The shifts of Mg/Ca, Sr/Ca and Ba/Ca records in SZ2 during the transition from MIS 5d to 5c apparently were earlier than the oxygen isotope record （δ180） of the same stalagmite. This possibly indicates （1） that atmospheric dust activity （the mechanism affecting SZ2 Sr/Ca and Ba/Ca ratios） is closely related to temperature, and （2） that temperature changes （dominated by solar insolation） precedes change in speleothem δSo records which are controlled by both summer monsoons and winter temperatures.

关 键 词：MIS系统 古气候变化 金属镁 川东北 石笋 中国 ICP-AES法 氧同位素记录 

分 类 号：P532[天文地球—古生物学与地层学] TP399[天文地球—地质学]