Geochemistry of Critical and Precious Metal Deposits

关键和贵金属矿床的地球化学

• 批准号: RGPIN-2017-04629
• 负责人: Linnen, Robert
• 金额: $ 1.97万
• 依托单位: University of Western Ontario
• 依托单位国家: 加拿大
• 项目类别: Discovery Grants Program - Individual
• 财政年份: 2020
• 资助国家: 加拿大
• 起止时间: 2020-01-01 至 2021-12-31
• 项目状态: 已结题
• 来源: https://www.nserc-crsng.gc.ca/ase-oro/Details-Detailles_eng.asp?id=710668
• 关键词: Geochemistry; Critical; Precious; Metal; Deposits

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.

我的研究计划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。关键金属有着光明的未来，因为它们被用于许多高科技设备的组件，特种合金等。贵金属目前是加拿大采矿业最强劲的部门。我的研究的长期目标是通过更好地理解负责富集金属的基本岩浆和热液过程，开发这些矿石存款类型的成因和勘探模型。最初的矿床模型是由行业和NSERC CRD赠款资助的免费研究产生的。然后，这些模型由发现资助研究进行测试，该研究的重点是对模型进行约束，并通过实验工作来测试假设。贵金属存款研究将包括黄铁矿矿物化学的研究，因为金通常作为包裹体出现在这种矿物中，并且在许多矿床中，黄铁矿丰度和金浓度之间存在总体上很强的相关性。黄铁矿是近年来众多研究的主题，但金在黄铁矿中的溶解度极限仍存在争议。将进行扩散实验，以确定真正的金的溶解度（相对于纳米nanonuggets）在黄铁矿。众所周知，金在黄铁矿中的溶解度强烈地依赖于砷的含量，因此实验将在无砷黄铁矿和含砷黄铁矿系统中进行。众所周知，自然金的化学性质是可变的。为了评估这些组合物是初始的还是再平衡的，需要知道扩散率。一系列的实验将确定铁，铜，镍和钴在自然金中的扩散率，并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，并且该矿物在其它环境中可含有wt%水平的铜和银。实验将确定温度、氧化还原条件、电气石成分和流体成分对铜-银-金配分的影响，并将结果应用于将电气石作为指示矿物。第二个研究领域侧重于关键金属。交代作用的重要性是稀有金属矿床中尚未解决的重要问题之一。最丰富的矿石矿物的关键金属含有二价阳离子作为主要成分。新的实验将评估二价阳离子交代在伟晶岩熔体的关键金属矿化的相互作用，钙，锰，铁丰富的流体与钽和钽丰富的熔体模拟交代作用。