Geochronology of Inner Solar System Materials Down to Atom Scale

从自然材料中恢复时间信息对于了解行星的历史和探索其矿产资源至关重要，而锆石等矿物的微晶是一种令人惊叹的工具。它们是最终的幸存者晶体，含有微量的铀，可用于确定整个太阳系历史上火山，构造，成矿和撞击事件的日期。在我目前的发现补助金的任期内，我建立了一个全国唯一的电子纳米束实验室（“ZAPLab”），并建立了一个新的方法，以地质年代学使用国家的最先进的电子显微镜。这使我们能够在以前未被识别的地方找到这些微晶，并测量它们的生长历史以及起源和大型陨石撞击等事件的干扰特征。我的团队将这种“结构时间”信息与铀的放射性同位素和稳定的子铅原子的化学时间记录结合起来。到目前为止，我的项目已经取得了突破性的成果，最近在我们发表在《自然》杂志上的文章中，我们解决了一个长达数十年的地质年代学难题，揭示了最常见的火星陨石最初形成于年轻的火星超级火山的侧面，而不是40亿年前的地壳（Moser et al. 2013 a）。由于我们与陨石档案管理员和收集者合作，在从月球到小行星带的太阳系内陨石中发现了大量其他测年矿物，预计还会有更多的发现。在接下来的五年里，我的团队还将使用原子探针建立一种新的地质年代学方法，原子探针是一种最近开发的材料科学仪器，可以让我们对晶体中的原子进行三维成像。我们将改进我们早期的结果，这些结果表明，在天然晶体中首次“看到”和测量化学和结构的时间记录是可能的。我的HQP团队还将使用新的ZAPLab工具来分析非洲和加拿大巨大撞击中的冲击微晶，以确定陨石坑事件期间U-Pb测年矿物行为的变化，以便我们能够更自信地解释我们在太阳系其他天体的陨石碎片中发现的东西。有了这个项目，我的团队将解决一些基本问题，比如精确地知道古代火星上何时有水流动。与此同时，ZAPLab的研究将侧重于解决经济地质学问题，如加拿大北极地区的矿石矿物和矿床的年龄和演变，萨德伯里撞击结构和其他地方的应用科学培训和知识转让有利于工业和提高ZAPLab的研究能力。我在测量晶体的取向和化学微观结构方面的专业知识也有助于帮助其他人测试制造材料的强度和耐腐蚀性，在拟议的发现资助期间，我将继续与化学家和工程师合作并在一系列项目中培训他们，例如正在考虑改善金属合金以确保放射性废物与环境的长期隔离。我的小组在向公众传达我们的研究结果和向加拿大工业转移知识方面有着良好的记录，上述研究的所有发现都将在每一个机会进行交流，就像CBC最近关于我的火星研究的在线文章和加拿大矿产勘探小组的实地考察一样。通过这种方式，我提出的研究计划将提供有关材料的年龄和/或性质的令人兴奋的额外发现，以造福加拿大科学和工业。

The recovery of time information from natural materials is essential to understanding the history of planets and the exploration of their mineral resources, and microcrystals of minerals such as zircon are an amazing tool for this. They are the ultimate survivor crystals and contain trace amounts of Uranium that can be used to date volcanic, tectonic, ore-forming, and impact events throughout solar system history. During tenure of my current Discovery Grant I have built a nationally unique electron nanobeam laboratory (the "ZAPLab") and established a new approach to geochronology using state-of-the-art electron microscopy. This allows us to find these microcrystals in places they've not previously been recognized, and to measure their growth history as well as signatures of origin and disturbance by events such as large meteorite impacts. My team combines this ‘structural time’ information with the chemical record of time preserved as ratios of radioactive isotopes of Uranium and the stable daughter Lead atoms. My program has so far yielded breakthrough results manifest most recently in our publication in the journal Nature in which we solved a decades-old geochronology puzzle to reveal that the most common Martian meteorites originally formed on the flanks of young Martian supervolcanoes rather than as 4 billion year old crust (Moser et al. 2013a). Many more discoveries are anticipated owing to our discovery in partnership with meteorite archivists and collectors of a large suite of other dating minerals in inner solar system meteorites ranging from the Moon to the Asteroid Belt. The next five years will also see my team establish a new geochronology approach using the Atom Probe, a recently developed instrument for materials science that allows us to image the atoms in crystals in three dimensions. We will improve on our early results that show it is possible to ‘see’ and measure chemical and structural records of time for the first time in natural crystals. My team of HQP will also use new ZAPLab tools to analyse shocked microcrystals in giant impacts in Africa and Canada to establish the variation in behaviour of U-Pb dating minerals during a cratering event so that we can more confidently interpret what we are finding in meteoritic fragments of other bodies in the solar system. With this program my team will tackle fundamental problems such as knowing precisely when water was flowing on ancient Mars. At the same time ZAPLab research will focus on solving economic geology problems such as the age and evolution of ore minerals and ore deposits in Arctic Canada, the Sudbury impact structure and elsewhere where applied scientific training and knowledge transfer is beneficial to industry and to improving ZAPLab research capacity. My expertise in measuring the orientation and chemical microstructure of crystals is also useful in helping others test the strength and corrosion-resistance of manufactured materials, and during the proposed Discovery Grant period I will continue to partner with and train chemists and engineers in a range of projects such as the improvement of metal alloys being considered for ensuring long-term isolation of radioactive waste from the environment. My group has an excellent track record of communicating the results of our research to the public and transferring knowledge to Canadian industry, and all findings from the above research will be communicated at every opportunity as with recent CBC online articles on my Martian research and site visits with Canadian mineral exploration groups. In this way my proposed research program will deliver exciting additional discoveries regarding the age and/or nature of materials to the benefit of Canadian science and industry.