柴达木盆地水—岩硼含量分布特征及其富集区域物源讨论

柴达木盆地盐湖是我国重要的硼资源富集区和成矿区。针对盆地内不同盐湖硼资源富集程度的差异性,采集柴达木盆地北缘河水和泉水样品,分析其硼和锂含量、矿化度和p H值,结合柴达木盆地不同流域补给水及蚀源区岩石已有的硼锂含量,总结盆地水—岩体系硼锂含量地球化学特征,并对柴达木盆地北缘富硼盐湖物源进行了探讨。结果表明,柴达木盆地北缘祁连山流域水体和岩石硼含量均较阿尔金山和昆仑山流域高,而其锂含量均较昆仑山那棱格勒河流域低,显示柴达木盆地北缘水—岩相对富硼贫锂的地球化学特征。综合对比柴达木盆地不同流域硼锂资源分布,显示出整个盆地硼锂含量的不均一性和不同步性特征。针对柴达木盆地北缘富硼盐湖的物源研究,主要归纳为祁连山系围岩(含电气石花岗岩)的风化淋滤、深部富硼地下水补给和含盐风成沉积溶滤输入成因,其中深部富硼地下水补给为最主要的来源。

The Distribution Characteristics of Boron in Water-Surrounding Rocks in Qaidam Basin and Discussion on the Source of Its Enrichment Area

The salt lakes in Qaidam Basin (QB) are important boron-rich and metallogenic area in China.According to the heterogeneity of boron concentrations in different salt lakes in the QB,this paper collected river and spring samples from the northern margin of Qaidam Basin (NQB) and analyzed the contents of boron and lithium,total dissolved solids (TDS) and pH values.Combined with the pereviously published data of boron and lithium contents in river waters-surrounding rocks from different catchments of QB,the geochemical characteristics of boron and lithium content in the water-rock system of the basin were summarized.Meanwhile,the source of boron-rich fluids in the NQB was also discussed.The results indicate that the boron contents in water and rocks in the Qilian Mountain catchment in NQB are higher than those in the Altyn and Kunlun Mountain catchments.On the contrary,the lithium contents in waters and rocks in the Qilian Mountain catchment are lower than those in the Nalenggele River of the Kunlun Mountain catchment.This comparison takes on a geochemical characteristic of boron-rich and lithium-poor in NQB,implying that boron and lithium resources from different catchments of QB are heterogeneous and asynchronous.The source of boron-rich fluids in NQB is summarized as the weathering and leaching of the surrounding rock (tourmaline-bearing granite) of the Qilian Mountains,recharging from boron-rich deep waters and the saline aeolian deposit leaching input.