Tracing battery metal (Li) mobility in pegmatite systems

全球经济的脱碳是一项紧迫的挑战，地球科学将在其中发挥关键作用。未来几十年，向可再生发电和存储的过渡将要求关键金属的来源大幅增加，特别是锂离子电池的关键组成部分锂(Li)。预计锂的来源将显著增加，因此更好地认识和勘探迄今研究较少的含锂矿床是一个新的紧迫的焦点。在地质上，锂主要与富硅伟晶岩的侵入有关。这些矿床通过高度演化的岩浆的提取，或通过富锂和富硅来源(如变质沉积物)的部分熔融，形成内花岗岩。然而，伟晶岩演化的精确机制：(I)熔体形成(Ii)金属赋存，(Iii)复杂结晶，特别是(Iv)控制经济成矿的条件，知之甚少，阻碍了Li(和Li-Cs-Ta-Sn)矿床形成模式和新勘探工具的开发。本项目将制定一项动态研究计划，涉及(I)至少一个研究区(津巴布韦)的野外观察和采样，重点是利用横切关系和深入花岗岩的断面来研究花岗岩单元的侵位历史，以建立侵位历史和成矿事件的三维视图；(2)通过激光烧蚀ICPMS对矿物物相进行矿物地球化学，以跟踪个别样品中矿物生长记录的结晶历史；以及(3)热力学-地球化学模拟，以约束成矿物理化学条件。还可以采取一系列其他原地和全岩地球化学和同位素方法。分析工作将在圣安德鲁斯大学和英国地质调查局(BGS)进行。圣安德鲁斯地质年代学实验室(STAGE)和同位素地球化学实验室(STAIG)配备了各种基于溶液和激光消融的MC-ICPMS和QQQ-ICPMS设施，以进行矿物相的现场痕量元素和同位素分析。此外，圣安德鲁斯化学学院配备了电子微探针和扫描电子显微镜，以进行现场分析和基于电子的成像。BGS的地质年代学和示踪器设施提供了一系列可用的仪器，包括新安装的用于矿物分离的SELFRAG(高压碎裂系统)仪器；该项目的最终目标是研究研究地点(S)的活动性Li，来源的作用，这些金属的普通地壳丰度是否足以产生经济矿床，岩浆演化和蒸汽饱和过程中金属的活动性的性质，以及矿化和贫化伟晶岩之间的不同成因，以建立广泛适用的成因模型。该项目中使用的多学科方法有可能改变我们对此类系统的理解，其结果将引起岩石学家、经济地质学家和勘探公司的广泛兴趣。更好地表征含电池金属的花岗岩-珠光岩系统最终将有助于它们的勘探和开采，有助于确保这种对社会脱碳至关重要的金属的新供应。将接受以下分析技术和软件的培训：-LA ICPMS-EPMA和SEM-地球化学家工作台-SuperPHREEQC和PHREEQC-ThermoCalc

The decarbonisation of the global economy is a pressing challenge in which Geoscience will play a key role. The transition to renewable power generation and storage will require a significant uptick in the sourcing of key metals over the next few decades, in particular lithium (Li), a key component of Li-ion batteries. A significant uptick in the sourcing of Li is predicted, hence a new and urgent focus in better understanding and exploring for Li-bearing deposits, which have hitherto been poorly studied.Geologically, Li are principally found associated with the intrusion of silica-rich pegmatites. This deposits form endogranitic with the extraction of highly evolved magma, or by partial melting of Li- and Silica-rich sources (e.g., metasediments). Nonetheless the precise mechanisms of pegmatite evolution: (i) melt formation (ii) metal endowment, (iii) complex crystallization and specially (iv) the conditions that control economic mineralization, are poorly understood, hindering models of Li (and Li-Cs-Ta-Sn) deposit formation and development of new exploration tools.This project will develop a dynamic research plan involving (i) field observations and sampling in at least one study area (Zimbabwe) with focus on the emplacement history of granite units using cross-cutting relationships and transects deep into the granite to build 3 dimensional views of the emplacement history and ore events; (ii) mineral geochemistry on mineral phases by laser ablation ICPMS to track crystallisation histories recorded by mineral growth within individual samples; and (iii) thermodynamic-geochemical modelling to constrain mineralization physico-chemical conditions. A range of other in-situ and whole-rock geochemical and isotopic approaches may be undertaken. Analytical work will be carried out at the University of St Andrews and the British Geological Survey (BGS). The St Andrews Geochronology Laboratory (StAGE) and Isotope Geochemistry Laboratory (StAIG) are equipped with a variety of solution-based and laser ablation MC-ICPMS and QQQ-ICPMS facilities to undertake in-situ trace element and isotopic analyses of mineral phases. Additionally, the St Andrews School of Chemistry is equipped with an electron microprobe and SEM to perform in-situ analysis and electron-based imaging. The Geochronology and Tracers Facility at the BGS provides a wide range instrumentation available including a newly installed SELFRAG (high-voltage fragmentation system) instrument for mineral separation; laser ablation MC and SF -ICP-MS instruments, a low-Pb blank clean suite, and a state-of-the-art Isotopx TIMS for high- precision (CA)-ID-TIMS U-Pb geochronology.The ultimate goal of the project is to characterize the mobility Li in the studied site(s), the role of source and whether ordinary crustal abundances of these metals are sufficient to generate economic deposits, the nature of metal mobility during magmatic evolution and vapour saturation, and the different petrogenesis between mineralized and barren pegmatites, to build widely applicable genetic models. The multi-disciplinary approach used in this project has the potential to transform our understanding of such systems and the results will be of wide interest to petrologists, economic geologists, and exploration companies. Better characterization of battery metal-bearing granitic-pegamatite systems will ultimately help in their exploration and extraction, helping ensure new supplies of this metal key to the decarbonisation of society.Training will be taken in the following analytical techniques and software:-LA ICP MS-EPMA and SEM-Geochemist Workbench-SuperPHREEQC and PHREEQC-ThermoCalc