矿物自动分析系统在碳酸岩型稀土地球化学勘查中的应用

Application of automated mineral analysis systems in geochemical exploration of carbonatite-related REE deposits

为稳固中国稀土资源大国地位,近年来我国不断加强稀土资源勘查力度。地球化学勘探是矿产勘查重要手段,本文通过总结以往稀土化探工作,查明其中存在的问题并提出解决方案。总结前人工作发现,碳酸岩型稀土矿致异常具有衬度低、规模小的特点,其原因主要是:①相对地壳丰度,稀土矿工业品位富集程度较低,容易被花岗岩等引起的非矿致异常稀释;②稀土成矿指示性矿物粒度小、分选难,对其表生迁移富集规律认识不深,难以制定有针对性的采样方法。基于扫描电镜和能谱的自动矿物分析系统,可实现微米级稀土矿物的化学成分和形貌参数的定量统计,为稀土矿物表生迁移规律研究提供基础。近年来在化探领域,前人利用矿物自动分析系统开展矿体—水系沉积物系统中微细粒矿物含量变化规律研究,显示出该方法的良好应用前景。未来可利用矿物自动分析系统开展:①风化过程中稀土矿物粒度变化规律研究;②矿体—水系沉积物系统中稀土矿物迁移富集规律研究。通过厘清矿体—土壤—水系沉积物系统中稀土成矿指示性矿物的分布特征和迁移富集规律,为稀土化探工作提供理论支撑。

In recent years,China has been strengthening the exploration of rare earth resources in order to secure the status of China as a large rare earth resource country.Geochemical exploration is an important means of mineral exploration,This paper summarizes the geochemical exploration of rare earth,finds out the existing problems and puts forward solutions.The carbonatite related rare earth anomalies are characterized by low contrast and small scale,the reasons are:①the industrial grade of rare earth ore is enriched to a low degree relative to the abundance of the earth's crust,which is easily diluted by non-mineral anomalies caused by granite,etc.;②the size of rare earth ore-forming indicator minerals are small and difficult to sort by traditional method,thus the epigenetic migration and enrichment pattern is not well understood,and it is difficult to develop a targeted sampling method.The automatic mineral analysis system based on scanning electron microscopy and energy spectrum can realize the quantitative statistics of chemical composition and morphological parameters of rare earth minerals at the micron level,which provides the basis for the study of epigenetic migration pattern of rare earth minerals.In recent years,in the field of geochemical exploration,previous research on the variation pattern of micro scale grain mineral content in the ore body-stream sediment system using the automatic mineral analysis system has shown the good application prospect of this method.In the future,the automatic mineral analysis system can be used to carry out:①research on the change of rare earth mineral size during weathering process;②research on the migration and enrichment of rare earth minerals in the ore body-aqueous sediment system.Thus,the distribution characteristics and migration and enrichment rules of rare earth indicative minerals in ore-body,soil-stream sediment system are clarified,providing theoretical support for geochemical exploration of rare earth.