西藏麻米错富硼锂盐湖成矿物质平衡计算与物质来源

Calculation of ore-forming material balance and material source of Li-B rich brines in Mami Co Lake,Tibet

麻米错盐湖是西藏境内发育的特大型锂矿床之一,目前对该盐湖的Li、B来源仍存在一定争议。文章系统采集麻米错盐湖水及周边补给水体样品,分析其主量元素特征,并使用多种水化学手段进行讨论,同时对盐湖水、河水及地热水进行蒸发模拟。结果表明,研究区河水及泉水中的主要离子受控于流域内岩石风化作用,其中碳酸盐岩矿物与蒸发岩矿物贡献最大,其次是硅酸盐矿物。文章对补给水体输入盐湖的Li、B资源进行定量计算,得出单纯通过河水和泉水的输入无法形成盐湖目前的探明储量。选择西藏地区最为富Li的地热水同补给水体按照一定比例混合后进行蒸发模拟,发现其析盐序列与盐湖水的析盐序列存在很大程度上的重叠,以上均证明麻米错盐湖中的Li、B资源除受到周边河水及泉水的补给外,还受到地热水的补给。

Mami Co Salt Lake is one of the super-large lithium ore salt lakes developed in Tibet.However,there are still disputes about the sources of Li in this area.In this study,we systematically collected several samples from Mami Co Salt Lake water and surrounding recharge water bodies and analyzed major element characteristics.A variety of hydrochemical methods are used for discussion,and the salt evolution sequence of salt lake water,river water and geothermal water evaporation simulation process is studied at the same time.The results show that the main ions in the river water and spring water in the study area are controlled by the weathering of rocks in the basin,in which carbonate and evaporate minerals contribute the most,followed by silicate minerals.Through quantitative calculation of Li and B balance,we found that the current proved resource reserves of the salt lake cannot be reached only by the input of river water and spring water,indicating that there is another important recharge source of Li and B in Mami Co Salt Lake.Due to the strong hydrothermal activity in the northern Tibetan plateau where the salt lake is located during the geological history,geothermal water contributes to salt lake resources.We select the most Li-rich geothermal water in Tibet to mix with rivers and springs in the study area in a certain proportion,and simulate the evaporation process by PHREEQC software.It is found that there is big overlap in the aspect of evolution sequence between the mixed water body and salt lake water.The salt evolution sequence of the mixed water body composed of river water and spring water is very different from that of salt lake water.It shows that Mami Co Salt Lake in the study area is not only supplied by surrounding rivers and springs,but also by geothermal water.