Crustal evolution and implications for mineralisation processes

含矿热液系统得到了深入的研究，但控制热液方解石、重晶石和伴生金属的形成及其与流体/岩浆来源的联系的地球化学过程很少受到限制。我的长期目标是展示来自地壳和地幔储藏的岩浆和流体如何为我们星球的构造和成矿演化做出贡献。这一建议的目的是调查流体/岩浆组成和沉淀速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。破译这些参数需要新的、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以用来模拟岩浆/流体的来源和组成。我建议通过比较在受控条件下沉淀的方解石(其次是重晶石)和自然环境中的热液方解石的同位素组成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。这种新的实验和多同位素方法将结合整个岩石和矿物尺度上的放射性成因和稳定同位素，以研究热液流体的来源和控制过程，以及它们与围岩和岩浆的相互作用。我的工具箱包括新的放射性成因/稳定锶同位素组合系统以及传统的放射性成因(Nd，Hf)和稳定(O，C)同位素。放射性成因/稳定锶同位素技术既提供了同位素示踪剂(放射性成因87/86锶)，又提供了对流体成分变化(钙/锶比)和碳酸盐从流体中沉淀/溶解敏感的过程监测(稳定的88/86锶)。 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。这一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组成和沉淀速率如何影响使用凝灰岩矿床的方解石的形成，以及碳酸盐赋存的金(卡林型)和铅锌矿床的形成。在较高的温度下，热液方解石实验和岩石学研究将有助于约束更复杂的碳酸盐-硅酸盐热液系统中的地幔/地壳来源和成矿过程，如1)碳酸盐岩-正长岩套和2)与侵入有关的金矿系统中的金-碳酸盐-石英脉。 这项研究计划将限制加拿大和全球矿产勘探业感兴趣的黄金和稀有金属矿床的来源，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.