Mass transfer of volatile and ore-forming elements in the Earth's lithosphere

地球岩石圈中挥发性元素和成矿元素的传质

• 批准号: RGPIN-2014-04805
• 负责人: Zajacz, Zoltan
• 金额: $ 2.7万
• 依托单位: University of Toronto
• 依托单位国家: 加拿大
• 项目类别: Discovery Grants Program - Individual
• 财政年份: 2018
• 资助国家: 加拿大
• 起止时间: 2018-01-01 至 2019-12-31
• 项目状态: 已结题
• 来源: https://www.nserc-crsng.gc.ca/ase-oro/Details-Detailles_eng.asp?id=669530
• 关键词: Mass; transfer; volatile; ore; forming

The major goal of this research program is to improve our understanding of the mass transfer of ore-forming and volatile elements in the Earth's solid crust, leading to the formation of ore deposits. The genesis of several types of mineral deposits is linked to magmatism, and the research proposed here focuses on the understanding of processes leading to the formation of so called "magmatic-hydrothermal" ore deposits. This subclass of mineralizations serves as our primary or major resource of elements such as Cu, Mo, Au, Sn, W, Re, Ag, Pb and Zn. The formation of such deposits relates to the exsolution of a volatile phase from magmas in response to decompression and crystallization, the same process which drives explosive volcanic activity. This is an essential step in ore formation, because this exsolving volatile phase may efficiently extract metals from magmas, and later precipitate them leading to local enrichment of specific ore metals. This exsolving magmatic volatile phase (MVP) is usually dominated by water and smaller amounts of CO2, but also contains S, Cl and various metals in significant concentrations. The concentration and speciation of S and Cl in the MVP exert primary control on the efficiency of ore metal extraction from magmas, and also affect the transfer to, and precipitation at the site of mineralization. *The comprehensive research program proposed here addresses this key process of metal extraction from magmas, and also those that control the initial metal endowment of the magmas before the exsolution of a magmatic volatile phase. We will combine observations made directly on natural samples with experimental investigations conducted at high pressures and temperatures simulating the physical-chemical conditions in geologic systems. The experimental studies will first focus on the volatile/melt partitioning of S and Cl, and the solubility and partitioning behavior of Cu and Au, using a range of innovative methodologies. The ultimate goal is to use this experimental dataset along with previously published data to construct a thermodynamic model which can accurately predict the volatile/melt partition coefficients of these elements as a function of pressure, temperature and melt composition. The studies on natural samples will track the co-variation of the concentration of volatile elements and ore forming metals in various magmatic-hydrothermal ore forming systems throughout the magmatic and/or hydrothermal evolution. Most data will be obtained by analyzing silicate melt-, sulfide- and fluid inclusions in minerals. These are tiny droplets of these phases (~10 to 100 µm), which are trapped in crystallizing minerals during the evolution of these systems, preserving a time resolved record of their compositional variation. The analysis of these inclusions poses an analytical challenge; however, a state of the art laboratory will be set up at the University of Toronto for this purpose. This will allow the detection of some element concentrations down to the parts per billion level for optimal samples. All these data will be integrated to construct improved models of magmatic-hydrothermal ore genesis.*Improved genetic models of ore formation will allow developing more rigorous exploration criteria for the mining industry and serve as a foundation for the discovery of new ore deposits. Securing the constant supply of mineral resources is essential for economic growth, comfortable human life and global peace. Due to its natural endowment of ore deposits, Canada may play a strategic role in covering the rapidly growing resource demands of society. Therefore, efficient mineral exploration may boost the growth of the Canadian economy, generate wealth for Canadians and increase Canada's influence in world politics.

该研究计划的主要目的是提高我们对地球固体地壳中矿石形成和挥发性元素的传质的理解，从而导致矿床的形成。几种类型的矿藏的起源与岩浆作用有关，此处提出的研究重点是理解导致所谓的“岩浆 - 流热矿床”的过程。这种矿化子类是我们的主要或主要资源，例如Cu，Mo，au，sn，W，Re，Ag，Pb和Zn。这种沉积物的形成涉及从岩浆响应解压缩和结晶的挥发相的实现，这是驱动爆炸性火山活性的相同过程。这是矿石形成的重要步骤，因为这个稳定的挥发性相可以有效地从岩浆中提取金属，后来又是珍贵的，从而导致特定矿石金属的局部富集。该解析的岩浆挥发相（MVP）通常由水和较少量的二氧化碳主导，但还以显着浓度的S，CL和各种金属含有。 MVP中S和CL的浓度和规范对矿石从岩浆中提取矿石的效率产生主要控制，并影响矿化部位的转移和降水。 *这里提出的综合研究计划探讨了从岩浆中提取金属的关键过程，以及那些在岩浆挥发阶段实现岩浆之前控制岩浆初始金属end赋的过程。我们将将直接对天然样品的观察结果与在高压和温度下进行的实验研究结合，以模拟地质系统中的物理化学条件。实验研究将首先关注S和CL的挥发性/熔体分区，以及使用一系列创新方法的Cu和Au的溶解度和分配行为。最终的目标是使用此实验数据集以及先前发布的数据来构建热力学模型，该模型可以准确地预测这些元素的挥发性/熔体分区系数，这是压力，温度和熔体组成的函数。关于天然样品的研究将跟踪在整个岩浆和/或热液演化中，在各种岩浆 - 热热矿石形成系统中，挥发性元素和矿石形成金属的浓度的共同变化。大多数数据将通过分析矿物质中的有机硅，硫化物和流体夹杂物获得。这些是这些相的微小液滴（〜10至100 µm），它们在这些系统的演变过程中被困在结晶的矿物中，并保留了其组成变化的时间记录。对这些夹杂物的分析提出了一个分析挑战。但是，为此，将在多伦多大学建立最先进的实验室。这将使某些元素浓度降低到最佳样品的每十亿级零件。所有这些数据都将集成以构建改进的岩浆 - 水热矿石创世纪的模型。确保不断的矿产资源供应对于经济增长，舒适的人类生活和全球和平至关重要。由于其自然的矿石矿床，加拿大可能在涵盖社会迅速增长的资源需求方面发挥战略作用。因此，有效的米粉勘探可能会促进加拿大经济的增长，为加拿大人带来财富，并增加加拿大在世界政治中的影响力。