Deglacial variations of Sr and Sr-87/Sr-86 ratio recorded by a stalagmite from Central China and their association with past climate and environment

• Published in: Chemical Geology
• Main Authors: Zhou, Houyun, Feng, Yue-xing, Zhao, Jianxin, Shen, Chuan-Chou, You, Chen-Feng, Lin, Yin
• Other Authors: Earth Dynamic System Research Center
• Language: English
• Published: Elsevier 2009
• Subjects: Speleothem; Strontium; Strontium isotope ratio; The last deglaciation; Wind-blown dust; Central China; Greenland; Greenland ice cores
• Online Access: https://doi.org/10.1016/j.chemgeo.2009.09.003; http://ir.lib.ncku.edu.tw/handle/987654321/98128

A low-resolution strontium isotopic ratio (Sr-87/Sr-86) record coupled with a high-resolution Sr concentration profile covering the last deglacial period were obtained for a stalagmite, SJ3. collected from Songjia Cave, northeast Sichuan province, Central China. Both Sr and Sr-87/Sr-86 display significant variations during the period between 20 and 10 ka, which correlate well with oxygen isotope records from Greenland ice cores and speleothems in the East Asian summer monsoon regime, with higher Sr and more radiogenic Sr-87/Sr-86 values occurring during cold-dry climatic phases and vice versa. The Sr in SJ3 shows a negative linear relationship between 8(87)Sr/Sr-86 and 1/Sr, suggesting the binary mixing of two end-members, the host rock of Late Permian limestone with a relatively lower Sr-87/Sr-86 ratio (similar to 0.7071) and an exotic Sr source with a relatively radiogenic Sr-87/Sr-86 ratio (similar to 0.7109 deduced from the Sr-87/Sr-86-1/Sr correlation). Atmospheric dust activity was suggested to be the most probable factor influencing the two indices. Because the carbonate fraction in wind-blown dust is enriched in Sr and has a more radiogenic Sr-87/Sr-86 ratio, enhanced atmospheric dust activity under stronger Asian winter monsoon which is associated with cold-dry climate would lead to higher Sr concentrations and more radiogenic Sr-87/Sr-86 ratios in SJ3 and vice versa. This interpretation is supported by the general parallelism of the two Sr indices to winter monsoon proxy from East Asia such as the dust flux and quartz median diameter in Luochuan loess profile during the same period. This study suggests that the speleothem Sr-87/Sr-86 ratio and Sr concentration, especially the former in northeastern Sichuan Province can be used to investigate the atmospheric dust activity and Asian winter monsoon. (C) 2009 Elsevier B.V. All rights reserved.