Modelling the genesis of the Separation Rapids petalite-lepidolite pegmatites as a guide to their exploration

模拟分离急流的透锂长岩-锂云母伟晶岩的成因，作为其勘探的指南

• 批准号: 518969-2017
• 负责人: WilliamsJones, Anthony
• 金额: $ 2.15万
• 依托单位: McGill University
• 依托单位国家: 加拿大
• 项目类别: Collaborative Research and Development Grants
• 财政年份: 2021
• 资助国家: 加拿大
• 起止时间: 2021-01-01 至 2022-12-31
• 项目状态: 已结题
• 来源: https://www.nserc-crsng.gc.ca/ase-oro/Details-Detailles_eng.asp?id=719489
• 关键词: Modelling; genesis; Separation; Rapids; petalite

Lithium is in very high demand because of concerns about global warming and government decisions to replace gasoline and diesel vehicles with electric vehicles powered by lithium-ion batteries. This demand also strongly affects other applications requiring lithium, notably in the ceramic/glass industry. A lithium mineral that is particularly sought by the ceramics and glass industry is petalite, because of its high capacity to reduce thermal shock. Significantly, in the Separation Rapids pegmatites, Ontario, Canada has one of the largest petalite resources in the World plus large resources of lepidolite, another important lithium mineral. The research described in this proposal is designed to investigate the nature, distribution and origin of these petalite-rich pegmatites as part of an overall objective to determine their genesis and develop tools that will be important to their successful exploration. The pegmatites belong to the LCT (Lithium-Cesium-Tantalum) class of pegmatites, for which there is no consensus on genesis. Two hypotheses currently dominate our view of their origin, the water-saturated magma hypothesis of Jahns and Burnham (1969) and the water-undersaturated hypothesis of London (1992). According to the former hypothesis, pegmatitic textures result from saturation of the magma with water, which lowers viscosity and suppresses nucleation, whereas for the latter hypothesis, they are explained by crystallisation from a boundary layer liquid enriched in network modifier elements (B, P and F) that reduce the viscosity. For both models, mineral chemistry, in predicting magma evolution, will provide tools for targeting lithium-rich pegmatites. If the Jahns and Burnham (1969) model is correct, then hydrothermal fluids would have affected the host rocks, and their lithogeochemistry could be used to develop vectors towards lithium-rich pegmatites. In this project, we will make use of a combination of petrographic, mineral chemical, isotopic, melt/fluid inclusion, and thermodynamic analyses to develop a robust genetic model for the Separation Rapids pegmatite field. The study will shed new light on the origin of a poorly understood strategic class of mineral deposits and, identify new guidelines for their exploration.

由于对全球变暖的担忧以及政府决定用锂离子电池驱动的电动汽车取代汽油和柴油汽车，锂的需求量非常大。这种需求也强烈影响其他需要锂的应用，特别是陶瓷/玻璃行业。透锂长石是陶瓷和玻璃工业特别寻求的一种锂矿物，因为它具有高减少热冲击的能力。值得注意的是，加拿大安大略省的分离急流伟晶岩拥有世界上最大的透锂长石资源之一，以及大量锂云母资源，这是另一种重要的锂矿物。本提案中描述的研究旨在调查这些富含透锂长岩的伟晶岩的性质、分布和起源，作为确定其成因并开发对其成功勘探至关重要的工具的总体目标的一部分。伟晶岩属于LCT（锂-铯-钽）伟晶岩类，其成因尚未达成共识。目前，我们对其起源的看法主要有两种假说：Jahns 和 Burnham (1969) 的水饱和岩浆假说和 London (1992) 的水不饱和假说。根据前一种假设，伟晶结构是由于岩浆被水饱和而产生的，这会降低粘度并抑制成核，而对于后一种假设，它们是由富含网络改性剂元素（B、P和F）的边界层液体结晶来解释的，这些元素降低了粘度。对于这两种模型，矿物化学在预测岩浆演化方面将提供针对富锂伟晶岩的工具。如果 Jahns 和 Burnham（1969）的模型是正确的，那么热液就会影响主岩，并且它们的岩石地球化学可用于开发富锂伟晶岩的载体。在这个项目中，我们将结合岩相学、矿物化学、同位素、熔体/流体包裹体和热力学分析，为分离急流伟晶岩领域开发一个强大的成因模型。这项研究将为人们了解甚少的战略矿藏类别的起源提供新的线索，并为其勘探确定新的指导方针。