白钨矿中稀土元素扩散作用的理论研究及实验模拟

Scheelite (CaWO4) is one of the most important ore minerals found among various types of tungsten deposit, its rare earth elements (REEs) characteristics and Sm-Nd isotopes are widely used for tracing material source, ore-formation process, and geochronology researches within various hydrothermal W-deposits. From the present situation, however, the condition of REEs hosting within scheelite has yet to be identified. Since closure ability of trace elements in mineral lattice mainly depends on their diffusion properties, it is very important to investigate the diffusion behavior of rare earth elements in scheelite. Theoretical calculation and experimental simulation are the most effective ways to study trace element diffusion in mineral lattice; and in previous studies, we have established an effective model for calculating diffusion parameters of rare earth elements in different minerals. Therefore, the objectives of this application are to constrain the diffusion behavior of REEs in sheelite in these two ways. By these studies, we can further understand the closure ability of REEs in sheelite within different geological environments, and get a theoretical basis for judging the reliability of REE records in scheelite from various tungsten-deposits.

白钨矿是热液矿床中常见的一种含钙矿物，通常能够容纳较高含量稀土元素，而且往往作为矿石矿物出现，故其稀土元素被广泛应用于示踪热液矿床的物质来源、形成过程以及年代学研究。但在何种地质环境中白钨矿内稀土元素的地球化学信息才能保持其原始记录，目前尚不清楚。地质环境下矿物中的微量元素及其同位素能否保持有效封闭，主要取决于其在矿物晶格中的扩散作用，因此，查明各种稀土元素在白钨矿中的扩散行为对于热液矿床研究具有重要意义。. 关于矿物晶格中元素扩散作用的研究，目前主要有理论计算和实验模拟两类方法，本项目拟从这两个不同方面对白钨矿中稀土元素的扩散行为进行研究，以查明其扩散性质，了解其在不同地质环境下的封闭状态，为判断白钨矿中稀土元素地球化学信息记录的可靠性提供理论依据。该项目的开展，有望为矿物中元素的扩散动力学研究提供新的思路，提高对稀土元素扩散性质的认识，并可促进我国在该领域的研究水平。