Geochemistry of Critical and Precious Metal Deposits

我的研究项目侧重于了解与侵入有关的关键金属(特别是钽、铌和稀土元素)和贵金属(金和铂族元素)矿床。关键金属具有广阔的前景，因为它们被用于许多高科技设备、特殊合金等的零部件中。贵金属是目前加拿大采矿业中最强劲的行业。我研究的长期目标是，通过更好地了解导致金属浓缩的基本岩浆和热液过程，开发这些矿床类型的成因和勘探模型。最初的矿床模型是由工业和NSERC CRD赠款资助的免费研究产生的。然后，这些模型由发现拨款研究进行测试，该研究的重点是对模型施加限制，并通过实验工作测试假设。贵金属矿床的研究将包括对黄铁矿矿物化学的研究，因为金通常以包裹体的形式出现在这种矿物中，而且在许多矿床中，黄铁矿丰度与金的浓度之间总体上有很强的相关性。黄铁矿是最近众多研究的主题，但金在黄铁矿中的溶解极限仍然存在争议。将进行扩散实验以确定真正的金在黄铁矿中的溶解度(而不是纳米金块)。众所周知，金在黄铁矿中的溶解度强烈依赖于砷的含量，因此将在无砷黄铁矿和含砷黄铁矿系统上进行实验。众所周知，自然金的化学成分也是多变的。为了评估这些成分是初级的还是再平衡的，需要知道扩散系数。一系列实验将确定铁、铜、镍和钴在自然金中的扩散系数，并将模拟自然矿床中金化学变化的意义。电气石是金矿床中常见的副矿物，在其他环境中这种矿物可含有wt%的铜和银。实验将确定温度、氧化还原条件、电气石组成和流体组成对铜-银-金分配的影响，并将结果应用于电气石作为指示矿物。第二个研究领域集中在关键金属上。稀有金属矿床中尚未解决的最重要问题之一是交代作用的重要性。关键金属中最丰富的矿石矿物主要成分为二价阳离子。新的实验将评估伟晶岩熔体中的二价阳离子交代作用，以实现关键金属矿化，方法是通过富钙、锰、铁的流体与富钽和富Nb的熔体相互作用来模拟交代作用。

My research program focuses on understanding intrusion-related critical metal (notably tantalum, niobium and rare earth elements) and precious metal (gold and platinum group element) deposits. The critical metals have a bright future because they are used in components in many high-tech devices, speciality alloys etc.. The precious metals are currently the strongest sector in the Canadian mining industry. The long term objectives of my research are to develop models for the genesis and exploration of these ore deposit types by better understanding the fundamental magmatic and hydrothermal processes that are responsible for concentrating metals. Initial ore deposits models are generated complimentary studies funded from industry and NSERC CRD grants. These models are then tested by Discovery grant research, which focuses on placing constraints on models and testing hypotheses through experimental work. Precious metal deposit research will include a study of pyrite mineral chemistry because gold commonly occurs as inclusions in this mineral and there is an overall strong correlation between pyrite abundance and gold concentration at many deposits. Pyrite has been the subject of numerous recent studies, but the solubility limits of gold in pyrite remain controversial. Diffusion experiments will be conducted to determine true gold solubilities (as opposed to nanonuggets) in pyrite. It is well known that gold solubility in pyrite is strongly dependent on arsenic content, hence experiments will be conducted on both arsenic-free pyrite and arsenic-bearing systems. It is also well known that the chemistry of native gold is variable. In order to evaluate whether these compositions are primary or re-equilibrated, diffusivities need to be known. A series of experiments will determine the diffusivity of iron, copper, nickel and cobalt in native gold and the significance of the variation of gold chemistry in natural deposits will be modeled. Tourmaline is a common accessory mineral in gold deposits and this mineral in other environments can contain wt% levels of copper and silver. Experiments will be conducted to determine the effects of temperature, redox conditions, tourmaline composition and fluid composition on copper-silver-gold partitioning and the results will be applied to using tourmaline as an indicator mineral. The second area of research focuses on critical metals. One of the most important unresolved problem in rare metal deposits is the importance of metasomatism. The most abundant ore minerals of critical metals contain bivalent cations as primary constituents. New experiments will evaluate bivalent cation metasomatism in pegmatite melts for critical metal mineralization by interacting calcium-manganese-iron-rich fluids with tantalum- and niobium-rich melts to simulate metasomatism.