9.9~4.2 kaBP STALAGMITE TRACE ELEMENTS RECORDS FROM SHIGAO CAVE, NORTHERN GUIZHOU PROVINCE AND ITS ENVIRONMENTAL SIGNIFICANCE

Stable isotope analysis and X-ray fluorescence core scanning have been carried out for trace elements of a ²³⁰Th dated stalagmite (No. SG-1) from the Shigao Cave of Northern Guizhou Province. The trace elements ratios of Mg/Ca, Sr/Ca, and Ba/Ca, displayed periodical changes. The Mg/Ca ratio is relatively low during 9.9~6.6 kaBP and increases gradually during 6.6~4.2 kaBP. The overall trend is correlated well with the δ¹⁸O record, suggesting that the Mg/Ca ratio is mainly subjected to the influence of precipitation. The retention time of karst water stayed in bedrock becomes shorter when precipitation increases, which will cause the decreases in the Mg/Ca ratio of the period; and vise versa. The variation tendency of Sr/Ca ratio and Ba/Ca ratio during 8.7~4.2 kaBP is corresponding to that of stalagmite δ¹³C in an opposite manner. Thus, vegetation and microbial activities in soil might be dominant factors affecting the Sr/Ca and Ba/Ca ratios. However, complicated relationship between the Sr/Ca, Ba/Ca ratios and δ¹³C occurs during 9.9~8.7 kaBP. It may be simultaneously influenced by various factors, such as temperature, precipitation, vegetation, and overlying soil. Therefore, when using the Ba/Ca and Sr/Ca ratios in the stalagmite as proxies for paleoclimate research, more emphasis should be laid on multi-proxies comparative study.