花岗质熔体中H2O含量与钨、锡溶解度和扩散系数的定量关系研究

H2O are the most important volatile component in magma, and directly affects the transfer and enrichment of ore-forming elements in the processes of magma evolution. In the whole ore-forming processes of tungsten and tin, the variable H2O content has significant effects on the transfer and enrichment of tungsten and tin, however, the related experimental research is very few, it is urgent to carry out the quantitative research about the effect of variable H2O content on the transfer and enrichment of tungsten and tin. This project intends to carry out the dissolution experiments of scheelite and cassiterite in granitic melts at high temperatures and high pressures using piston-cylinder apparatus, and, calculate the solubilities and diffusivities of tungsten and tin in granitic melts using the methods of the chemical kinetic theory which is the mathematic simulation of experimental data and solving the equations of diffusive crystal dissolution. And then, the quantitative relationship between H2O content in granitic melts and the solubility, diffusivity of tungsten and tin will be obtained. Finally, this project will show the effect of H2O on the transfer and enrichment of tungsten and tin, and also provide the experimental evidence for the further study on the magma evolution and the mechanism of transfer and enrichment of tungsten and tin.

H2O是岩浆中最重要的挥发组分，直接影响岩浆演化中成矿金属元素的迁移和富集。在钨、锡的整个成矿过程中，岩浆演化阶段的H2O含量变化对钨、锡迁移富集的影响至关重要，但相关的实验研究却相对缺乏，迫切需要开展熔体中H2O含量变化对钨、锡迁移富集机制影响的定量研究工作。本项目拟利用活塞-圆筒装置开展白钨矿（CaWO4）和锡石（SnO2）在花岗质熔体中溶解的高温高压实验研究，利用化学动力学理论对实验数据进行数学模拟，通过求解晶体的扩散溶解方程来计算平衡条件下W、Sn在花岗质熔体中的溶解度以及扩散系数，分别得到不同温度、压力、氧逸度条件下熔体H2O含量与W、Sn在花岗质熔体中溶解度和扩散系数之间的定量关系。最终，揭示岩浆演化进程中H2O含量变化对钨、锡迁移富集的影响作用，为深入研究岩浆演化与钨、锡迁移富集机制提供实验依据。

H2O是岩浆中最重要的挥发组分，直接影响岩浆演化中成矿金属元素的迁移和富集。在钨 、锡的整个成矿过程中，岩浆演化阶段的H2O含量变化对钨、锡迁移富集的影响至关重要，但相关的实验研究却相对缺乏，迫切需要开展熔体中H2O含量变化对钨、锡迁移富集机制影响的定量研究工作。钨锡成矿过程同时是一个不平衡、不可逆的动力学过程，动力学相关理论和方法较热力学更适合于研究其成矿元素的迁移富集机理。本项目利用高温高压实验结合一维无限熔体介质中晶体的扩散溶解模型研究W、Sn在花岗质熔体中的扩散作用，建立了反映温度（T）、氧逸度（fO2）和熔体中H2O含量（CH2O）与花岗质熔体中W、Sn的扩散系数（D）之间相互关系的定量模型，获取了钨锡成矿作用的关键影响因素，建立论文钨锡成矿作用过程的定量模型；揭示了岩浆演化进程中H2O含量变化对钨、锡迁移富集的影响作用，为深入研究岩浆演化与钨、锡迁移富集机制提供实验依据。