Crustal evolution and implications for mineralisation processes

地壳演化及其对成矿过程的影响

• 批准号: RGPIN-2019-07258
• 负责人: Stevenson, Ross
• 金额: $ 1.82万
• 依托单位: Université du Québec à Montréal
• 依托单位国家: 加拿大
• 项目类别: Discovery Grants Program - Individual
• 财政年份: 2022
• 资助国家: 加拿大
• 起止时间: 2022-01-01 至 2023-12-31
• 项目状态: 已结题
• 来源: https://www.nserc-crsng.gc.ca/ase-oro/Details-Detailles_eng.asp?id=755118
• 关键词: Crustal; evolution; implications; mineralisation; processes

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.

已经对含矿石的水热系统进行了深入的研究，但是控制水热方解石，稀块和相关金属的地球化学过程，它们与流体/岩浆源的联系受到了很大的约束。我的长期目标是展示地壳和地幔储层中的岩浆和液体如何促进我们星球的构造和金属源性演化。该提案的目的是研究流体/岩浆成分和降水速率如何影响水热方解石和芳基的地球化学和同位素组成。解密这些参数需要新的新型调查工具和方法。 我的研究表明，水热方解石的地球化学和同位素指纹可用于建模岩浆/流体来源和成分。我建议通过比较在受控条件下与自然环境中的水热方解石在受控条件下沉淀的方解石（和第二个碳酸盐）的同位素组成来研究水热系统的起源。这些实验将研究温度，流体组成和降水速率的变化如何影响刻度的稳定同位素组成。这种新型的实验和多分子方法将在整个岩石和矿物尺度上结合放射原和稳定的同位素，以检查控制水热流体的来源和过程，以及它们与壁岩石和岩浆的相互作用。我的工具箱包括新型的放射/稳定SR同位素系统以及传统的放射原（ND，HF）和稳定（O，C）同位素。放射/稳定的SR同位素技术既提供了同位素示踪剂（放射性87/86SR），也提供了对流体组成变化（CA/SR比）的变化敏感的过程监视器（稳定的88/86SR），又敏感流体。 这项研究有可能通过建模流体来源，成分和降水速率来改变我们对金属/矿物质来源的理解。该潜力将首先在相对简单的低温碳酸盐系统中进行测试，以提供研究更复杂的高温硅酸盐/碳酸盐系统的基础。在低温下，降水实验将研究流体成分和降水速率如何使用TUFA沉积物以及碳酸盐托管金（Carlin-type）和PB-ZN沉积物影响方解石的形成。 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-相关的黄金系统。 该研究计划将限制加拿大和全球矿产勘探行业的黄金和稀有金属矿床的起源，并生产具有高素质的人员，具有推进地球科学研究的技能。