摘要
西藏北羌塘盆地是我国侏罗系海相找钾的主要远景区之一,在多格错仁地区发育有一系列具有明显的含钾异常的现代盐泉,研究这些盐泉水的物质来源具有重要的找钾意义和科学价值。野外采集了40个盐泉水的样品,并在室内测定了其化学组分、δ34 S和87 Sr/86 Sr。分析结果显示,盐泉水具有富Na+、Ca2+、K+、Cl-,贫Mg2+、SO2-4、HCO-3的特征,其Cl-含量约占矿化度的50%以上,并与矿化度呈正相关关系,Na+、Ca2+、K+浓度也与矿化度呈正相关关系。根据盐泉水的钠氯系数和溴氯系数判断,盐泉水属于地层溶滤水;源泉河、东温泉、多格错仁湖南岸3处的盐泉水具有与侏罗纪海水相一致的硫同位素特征,表明其在地下运移时,很可能溶解了地层中的石膏沉积;盐泉水的1000/Sr-87Sr/86Sr投点图说明各处盐泉水在地下的运移路径和形成过程明显不同;盐泉水的87Sr/86Sr值与其区域背景值对比显示,盐泉水在形成过程中可能溶滤了夏里组二段和索瓦组一段中的蒸发岩,区内夏里组和索瓦组最有可能蕴含有成盐成钾层系。
North Qiangtang Basin in Tibet is one main Jurassic marine area of potash exploration. There is a series of modern springs with a potassium anomaly in Dogai Coring area. Research on origin of salt springs has an important significance for potash exploration and scientific value. For this study forty salt springs water samples were taken from field. Chemical composition, g4S and 87Sr/86 Sr of salt springs were determined in laboratory. Analysis results indicate that salt springs water have a high concentration of Na＋ , Ca2＋ , K＋ , C1- , and a poor concentration of Mg2＋ , SO2-4 , HCO3-. Content of C1- has more than 50% TDS and positive correlation with TDS. Moreover, Na＋ , Ca2＋ , K＋ have a positive correlation with TDS. According to nNa＋/nC1- and Br- ·103/C1- of salt springs, springs water are from stratum lixiviation water. The 834 S value of water samples from Yuanquanhe, Dongwenquan and south bank of Dogai Coring are consistent with 834S value of Jurassic seawater. It demonstrates that springs water might dissolve gypsum of stratum when springs water travelled under the ground. The figure of 1000/Sr-87 Sr/ 86Sr illustrates that migration path and forming process of springs water from every sampling location are different from each other. The comparison for 87 Sr/86 Sr of salt springs and its background value shows that groundwater might lixiviate evaporite from 2na Member of Xiali Formation and 1st Member of Suowa Formation. Xiali Formation and Suowa Formation are the most possible stratum of forming potash.
出处
《地质学报》
EI
CAS
CSCD
北大核心
2014年第6期1003-1010,共8页
Acta Geologica Sinica
基金
国家重点基础研究发展计划(973计划)项目(编号2011CB403003)
国土资源部盐湖资源与环境重点实验室开放基金项目(编号ZS1114)资助的成果
关键词
西藏多格错仁地区
盐泉
硫同位素
锶同位素
钾盐
Dogai Coring area,Tibet
salt springs
sulphur isotpe
strontium isotope
potash
