杨邦, 雷国良, 姜修洋. 黔北石膏洞9.9~4.2 kaBP石笋微量元素记录及环境意义[J]. 海洋地质与第四纪地质, 2014, 34(2): 143-148. DOI: 10.3724/SP.J.1140.2014.02143
引用本文: 杨邦, 雷国良, 姜修洋. 黔北石膏洞9.9~4.2 kaBP石笋微量元素记录及环境意义[J]. 海洋地质与第四纪地质, 2014, 34(2): 143-148. DOI: 10.3724/SP.J.1140.2014.02143
YANG Bang, LEI Guoliang, JIANG Xiuyang. 9.9~4.2 kaBP STALAGMITE TRACE ELEMENTS RECORDS FROM SHIGAO CAVE, NORTHERN GUIZHOU PROVINCE AND ITS ENVIRONMENTAL SIGNIFICANCE[J]. Marine Geology & Quaternary Geology, 2014, 34(2): 143-148. DOI: 10.3724/SP.J.1140.2014.02143
Citation: YANG Bang, LEI Guoliang, JIANG Xiuyang. 9.9~4.2 kaBP STALAGMITE TRACE ELEMENTS RECORDS FROM SHIGAO CAVE, NORTHERN GUIZHOU PROVINCE AND ITS ENVIRONMENTAL SIGNIFICANCE[J]. Marine Geology & Quaternary Geology, 2014, 34(2): 143-148. DOI: 10.3724/SP.J.1140.2014.02143

黔北石膏洞9.9~4.2 kaBP石笋微量元素记录及环境意义

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

  • 摘要: 通过对黔北石膏洞一石笋(编号SG-1)进行碳氧稳定同位素测试和XRF元素扫描分析,结果表明研究时段内Mg/Ca、Sr/Ca和Ba/Ca比值都表现了较明显的阶段性变化:Mg/Ca比值在9.9~6.6 kaBP偏低,6.6~4.2 kaBP期间逐渐升高,整体变化趋势与石笋δ18O变化趋势较为一致,呈正相关关系,表明石膏洞石笋Mg/Ca比值主要受降水的影响,即降水增多(δ18O偏负),岩溶水在母岩中滞留时间短,Mg/Ca比值降低;反之则升高。Sr/Ca和Ba/Ca比值在8.7~4.2 kaBP的变化与石笋δ13C变化趋势一致,呈反相关关系,植被和土壤微生物活动有可能是影响石膏洞石笋Sr/Ca和Ba/Ca的主要因素。但是在9.9~8.7 kaBP,Sr/Ca和Ba/Ca比值与石笋δ13C关系复杂,有可能同时受到温度、降水、地表植被和上覆土壤等众多因素的影响。因此,运用Ba/Ca和Sr/Ca进行古气候研究时需要慎重,要注重多指标对比研究。

     

    Abstract: 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.

     

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