世界天然碱矿床资源分布、成矿因素及找矿远景

Distribution and genesis of global Na-carbonate deposits and its prospecting potential

【研究目的】天然碱矿主要用于制纯碱,和合成碱相比,具有绿色环保、成本低的优势。其下游产业遍布各个领域,如玻璃、医药等。光伏等新能源产业的蓬勃发展给纯碱带来了新需求。中国是纯碱消费大国,天然碱或成为稀缺资源。天然碱矿是一种蒸发岩矿床,成矿过程具有重要的研究意义,国内蒸发岩矿床研究领域对天然碱矿的关注较少。理清世界天然碱矿产资源类型、分布特征,总结碱矿成因对深化中国天然碱矿成矿规律研究、预测找矿远景、寻找天然碱矿床具有积极意义。【研究方法】搜集已公开发表或出版的天然碱矿床资料,对世界典型矿床区域概况、物源、成因等内容进行系统总结。【研究结果】绝大部分天然碱矿床分布于北美洲、亚洲和非洲,主要形成于新生代。类型以现代天然碱矿床居多,古代天然碱矿床较少,但资源规模大。古代天然碱矿以美国绿河组、河南泌阳凹陷安棚天然碱矿最为典型,现代天然碱矿以肯尼亚马加迪湖和内蒙古查干诺尔泡碱矿床为典型。【结论】天然碱矿需要在封闭的构造环境、干旱的气候条件、充足的碳酸钠型卤水补给等成矿因素耦合条件成矿。与其他蒸发岩不同的是,维持碳酸钠型卤水所需的CO_(2)来源具有复杂性。中国天然碱矿找矿远景应聚焦内蒙古第四纪盐湖、白垩纪封闭凹陷,以及河南始新世白云岩、油页岩发育的封闭盆地等地。积极开展天然碱矿成矿理论研究和找矿工作具有重要意义。

This paper is the result of mineral exploration engineering.[Objective]Natural soda-ash deposits,also called sodium carbonate evaporites,are mainly used to produce soda ash.In the soda industry,compared with synthetic soda,this process has advantages for environmental protection and lower cost.The downstream industries contain various fields,including glass,medicine,and so on.The booming of new energy industries such as photovoltaic has brought new demand for soda ash.China consumes loads of soda ash annually;thus,soda may become a scarce resource in the future.Mineralization process of natural soda-ash evaporites is of great significance in evaporite community.In China however,soda-ash deposits have received little attention and have great research potential.Investigations on types and distribution characteristics of global soda-ash deposits and their genesis are helpful and useful for deepening research and prospecting of Nacarbonate deposits in China.[Methods]Compiling published data and systematically summarizing the regional setting,provenance,genesis of typical soda-ash deposits.[Results]Most deposits are Cenozoic in age and located in North America,Asia and Africa.Modern soda-ash deposits predominate in number,but resources size of ancient deposits is tremendous.Specific ancient deposits include the Green River Formation,United States and the Anpeng soda deposit in Biyang Depression in Henan,the counterparts,typical modern alkaline lake deposits formed in Lake Magadi,Kenya and Chaganor,Inner Mongolia.[Conclusions]The requirement for Na-carbonate deposits precipitation are(1)hydrologically-closed basins,(2)arid climate,and(3)sufficient sodium carbonate supply.Unlike other evaporites,the sources of CO_(2) required to maintain Na-carbonate brines are complicated.Efforts for prospecting in China should focus on Quaternary saline lakes,Cretaceous restrict basins in Inner Mongolia,and tectonically-closed depression in which dolomite and oil shale develops in Henan.It is of great significance to carry out the metallogenic theory research and mine prospecting.