隐伏铜矿元素迁移模拟实验及机理研究

With the discovery of outcropping ore deposits becoming more difficult, deep-penetrating geochemical techniques will increasingly be applied to the exploration of blind deposits. The mechanism of element migration, as the theoretical basis of such technology, has not been well explained, which has become a bottleneck restricting its development and promotion. Considering relative scarcity of copper resources in China, breakthrough on the theories and methods of copper exploration is urgent. This project intends to create monitoring points for simulation experiment of element migration in concealed copper deposits in two types of landscape areas; several simulated migration columns will be buried in each point. Through the methods of observation and sampling regularly in the field, the project will investigate the vertical variation of element contents and physicochemical properties in the overburden soil over the simulated migration columns, the horizontal changes of element contents and physicochemical properties between the upper part of columns and background soil, the characteristics of nano-metal particles in gas-solid media, the relationship of the changes of element contents with climatic conditions and earthgas, et al., and combine the element migration situations of simulated indoor columns established, to reveal the element migration process and mechanism of concealed copper deposits in different landscape types. The successful implementation of this project will further lay a more substantial theoretical foundation for the development of deep-penetrating geochemical methods, and have important theoretical and practical significance for the promotion the exploration of blind deposits and solving the problem of mineral resources.

随着发现出露矿的难度加大，深穿透地球化学技术必将越来越多地应用到隐伏矿勘查中，元素迁移机理问题作为此类技术的理论基础，一直未得到很好的解释，这已成为制约其发展并推广的瓶颈。考虑到我国铜矿资源相对稀缺，急需在铜矿勘查理论和方法上有所突破。本项目拟在两类景观地区建立隐伏铜矿元素迁移模拟实验监测点，每处埋置多个铜矿模拟迁移柱，通过野外定期采样观测的手段，研究模拟迁移柱上方覆盖层土壤中元素含量和理化性质的垂向变化、模拟迁移柱上方与背景区土壤中元素含量和理化性质的水平变化、气固介质中纳米金属微粒特征、元素含量变化与气候条件及地气流的关系等，并结合已建立的室内模拟迁移柱元素迁移情况，达到揭示隐伏铜矿中元素在不同景观类型条件下的迁移过程及迁移机理的目的。本项目的成功实施将进一步为深穿透地球化学方法的发展打下更坚实的理论基础，对隐伏矿勘查工作的推进和矿产资源问题的解决，具有重要的理论和现实意义。

元素迁移机理研究一直是近几十年勘查地球化学领域研究的前沿。为了进一步认识元素在自然界中的迁移方式，本项目在内蒙和新疆野外建立了两处隐伏铜矿模拟迁移柱，并结合室内已建成的模拟迁移柱开展了模拟迁移实验研究。项目通过定期采集迁移柱不同部位土壤样品，采集迁移柱上方地气和土壤中的微粒样品，并综合运用化学分析、理化性质分析、透射电镜分析、X粉晶衍射分析等手段来达到预期研究目的。通过本项目的实施，发现模拟迁移柱上方盖层土壤中的元素含量在实验前后发生了明显的变化，野外（放置隔板）和室内（加水）开展的差异实验则说明了元素迁移的可能途径，进一步推测认为，模拟条件下成矿元素是受地下水作用、氧化还原电位梯度、扩散作用、蒸发蒸腾作用、植物作用以及地气流等多种因素的共同影响，完成从两米深的矿石层向表层迁移的过程，在自然条件下，在上百万年的第四纪演化历史中，完成距离数百米迁移是完全有可能的，这为深穿透地球化学技术的使用提供了理论基础。此外，项目在矿石、模拟迁移柱矿体上方地气中和土壤中同时有效观测到金属纳米颗粒，颗粒大小、形貌特点、成分有极大的相似性，表明它们之间具有成因联系，同时也证实纳米金属微粒具有极强的穿透能力和快速迁移能力，这为元素在覆盖层中的迁移提供了实证性证据。