Geochronology of Inner Solar System Materials Down to Atom Scale

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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.