Crustal evolution and implications for mineralisation processes

含矿热液系统已被深入研究，但控制热液方解石，重晶石和伴生金属的形成的地球化学过程，以及它们与流体/岩浆源的联系，受到的限制很少。我的长期目标是证明来自地壳和地幔储层的岩浆和流体如何对我们星球的构造和成矿演化做出贡献。本提案的目的是调查流体/岩浆成分和沉淀率如何影响热液方解石和重晶石的地球化学和同位素组成。破解这些参数需要新的和新颖的调查工具和方法。 我的研究表明，热液方解石的地球化学和同位素指纹可用于模拟岩浆/流体来源和成分。我建议通过比较方解石（其次是重晶石）在受控条件下沉淀的同位素组成与自然环境中的热液方解石来研究热液系统的起源。这些实验将研究温度、流体成分和沉淀率的变化如何影响方解石的稳定同位素组成。这种新颖的实验和多同位素方法将在整个岩石和矿物尺度上结合联合收割机放射性同位素和稳定同位素，以检查热液流体的来源和控制过程及其与围岩和岩浆的相互作用。我的工具箱包括新的组合放射性/稳定Sr同位素系统以及传统的放射性（Nd，Hf）和稳定（O，C）同位素。放射性/稳定Sr同位素技术提供了同位素示踪剂（放射性87/86 Sr）和过程监测器（稳定88/86 Sr），对流体成分（Ca/Sr比）和碳酸盐从流体中沉淀/溶解的变化敏感。 这项研究有可能通过模拟流体来源，成分和沉淀率来改变我们对金属/矿物来源的理解。这种潜力将首先在相对简单的低温碳酸盐体系中进行测试，为研究更复杂的高温硅酸盐/碳酸盐体系提供基础。在低温下，沉淀实验将研究流体成分和沉淀率如何影响使用石灰华矿床的方解石的形成，以及碳酸盐岩型金矿（卡林型）和铅锌矿床。在较高温度下，热液方解石实验和岩石学研究将有助于限制地幔/地壳来源，以及更复杂的碳酸盐-硅酸盐热液系统中的成矿过程，例如1）碳酸岩-正长岩套和2）与侵入有关的金系统中的金-碳酸盐-石英脉。 该研究计划将限制加拿大和全球矿产勘探行业感兴趣的黄金和稀有金属矿床的起源，并培养具有推进地球科学研究技能的高素质人才。

Ore-bearing hydrothermal systems have been intensively studied, but the geochemical processes controlling the formation of hydrothermal calcite, barite and associated metals, and their links to fluid/magma sources, are poorly constrained. My long-term goal is to demonstrate how magmas and fluids from crustal and mantle reservoirs contribute to the tectonic and metallogenic evolution of our planet. The objective of this proposal is to investigate how fluid/magma compositions and precipitation rates affect the geochemical and isotopic composition of hydrothermal calcite and barite. Deciphering these parameters requires new and novel investigative tools and approaches. My research has demonstrated that geochemical and isotopic fingerprinting of hydrothermal calcite can be used to model magma/fluid sources and compositions. I propose to study the origin of hydrothermal systems by comparing the isotopic composition of calcite (and secondly barite) precipitated in controlled conditions with hydrothermal calcites from natural environments. These experiments will study how variations in temperature, fluid composition and precipitation rates affect the stable isotope composition of the calcites. This novel experimental and multi-isotopic approach will combine radiogenic and stable isotopes at the whole rock and mineral scale in order to examine the sources of, and processes controlling, hydrothermal fluids and their interaction with wall rocks and magmas. My toolbox includes the novel combined radiogenic/stable Sr isotope system as well as traditional radiogenic (Nd, Hf) and stable (O, C) isotopes. The radiogenic/stable Sr isotope technique provides both an isotopic tracer (radiogenic 87/86Sr), and process monitor (stable 88/86Sr) that is sensitive to changes in fluid composition (Ca/Sr ratio) and the precipitation/dissolution of carbonates from the fluid. This research has the potential to transform our understanding of metal/mineral sources by modeling fluid sources, compositions and precipitation rates. This potential will be tested first in relatively simple low temperature carbonate systems to provide a basis to study more complex high temperature silicate/carbonate systems. At low temperatures, the precipitation experiments will study how fluid composition and precipitation rates affect the formation of calcite using tufa deposits, and carbonate-hosted gold (Carlin-type) and Pb-Zn deposits. At higher temperatures, the hydrothermal calcite experiments and petrological investigations will help constrain mantle/crustal sources, and mineralizing processes in more complex carbonate-silicate hydrothermal systems such as 1) carbonatite-syenite suites and 2) gold-carbonate-quartz veins in intrusion-related gold systems. This research program will constrain the origin of gold and rare metal deposits of interest to the Canadian and global mineral exploration industry, and produce highly qualified personnel with the skills to advance geoscience research.