Untangling the Earliest Stages of Planetary Differentiation

The iron and stony-iron meteorites are fragments of protoplanets broken apart early in solar system history, providing a unique snap shot of processes during and after the earliest stages of core formation and planetary differentiation. In order to understand the geochemical and mineralogical patterns of these processes it is necessary to first understand which samples originate from common parent bodies, as this processes has been repeated many times, with samples of >>50 such bodies present in our meteorite collections.
High precision oxygen 3-isotope measurements are the only geochemical tool that allows us to readily explore the links between silicate-rich mantle and crustal rocks with the iron-nickel-rich iron meteorites that originate from protoplanetary cores. While silicates are rare in iron meteorites that formed by planetary differentiation other oxygen-bearing phases such as chromites and phospahates are more abundant and can be used to map out the relationships between different meteorites and groups.
The work will capatalise on the very small sample size (<100 micro gram) and high precision laser fluorination system at the Open University. A variety of sample preparation techniques will be employed (including microdrilling, acid dissolution) to investigate a number of key meteorite groups to understand their inter-relationships and processes that control isotopic fractionation during planetary differentiation.
The work will involve detailed petrography of iron and stony-iron meteorites using analytical SEM and electron microprobe to characterise the samples and their oxygen-bearing phases/inclusions.
Once clear groupings of samples have been identified, the minor and trace element geochemistry of the samples will be determined by ICPMS, which together with the mineralogy and isotopic measurements will be used to explore the processes of planetary differentiation - such as timescales, fractionation and partitioning processes, temperatures, body sizes, etc.