PhD in Geographical and Earth Sciences: Tracking the geological evolution of carbonaceous asteroids using carbonates

Start Date: October 2025

Aims: This project will use CM carbonaceous chondrite meteorites to explore the geological evolution of carbonaceous asteroids during the early history of the Solar System. Its aim is to understand the role of water- and organic matter-rich asteroids in delivering bio-essential compounds to early Earth, and so making conditions suitable for life.

Context and science questions:  Carbonaceous asteroids formed 4560 million years ago within the protoplanetary disk from mineral grains (silicates, sulphides, metal), organic matter and ices. Soon after the asteroids had been built, the ice melted and the liquid water that was produced reacted with mineral grains to create secondary phases including phyllosilicates (mainly serpentine) and carbonates (calcite, dolomite, aragonite). The carbonate minerals are particularly valuable and informative because their chemical and isotopic compositions, and microstructures, are powerful tools for understanding the geological evolution of these primitive bodies. Specifically, carbonates can provide unique insights into long-standing questions about asteroid evolution including the temperature and duration of water/rock interaction, the presence or absence of fluid flow, and the nature and timing of deformation by hypervelocity impacts (Lee et al. 2014).

This project comes at a uniquely important time in our understanding of the early Solar System and its most primitive bodies. Samples have recently returned from two carbonaceous asteroids: Ryugu (sampled by the Japan Aerospace Exploration Agency (JAXA) Hayabusa2 mission), and Bennu (sampled by the NASA OSIRIS-REx mission). Furthermore, a CM carbonaceous chondrite recently landed in Winchcombe, Gloucestershire, and was the first meteorite fall to be recovered in the UK for 30 years (King, Daly et al. 2022).

Methodology: Carbonate minerals in a variety of CM meteorites will be analysed using conventional microanalytical techniques (e.g., scanning  Aims: This project will use CM carbonaceous chondrite meteorites to explore the geological evolution of carbonaceous asteroids during the early history of the Solar System. Its aim is to understand the role of water- and organic matter-rich asteroids in delivering bio-essential compounds to early Earth, and so making conditions suitable for life.

Context and science questions:  Carbonaceous asteroids formed 4560 million years ago within the protoplanetary disk from mineral grains (silicates, sulphides, metal), organic matter and ices. Soon after the asteroids had been built, the ice melted and the liquid water that was produced reacted with mineral grains to create secondary phases including phyllosilicates (mainly serpentine) and carbonates (calcite, dolomite, aragonite). The carbonate minerals are particularly valuable and informative because their chemical and isotopic compositions, and microstructures, are powerful tools for understanding the geological evolution of these primitive bodies. Specifically, carbonates can provide unique insights into long-standing questions about asteroid evolution including the temperature and duration of water/rock interaction, the presence or absence of fluid flow, and the nature and timing of deformation by hypervelocity impacts (Lee et al. 2014).

This project comes at a uniquely important time in our understanding of the early Solar System and its most primitive bodies. Samples have recently returned from two carbonaceous asteroids: Ryugu (sampled by the Japan Aerospace Exploration Agency (JAXA) Hayabusa2 mission), and Bennu (sampled by the NASA OSIRIS-REx mission). Furthermore, a CM carbonaceous chondrite recently landed in Winchcombe, Gloucestershire, and was the first meteorite fall to be recovered in the UK for 30 years (King, Daly et al. 2022).

Methodology: Carbonate minerals in a variety of CM meteorites will be analysed using conventional microanalytical techniques (e.g., scanning electron microscopy, electron backscatter diffraction, electron probe microanalysis, Raman spectroscopy) together with the novel tool of atom probe tomography, which enables determination of the chemical and isotopic composition of a sample at the atomic scale (Daly et al. 2020).

Dissemination and skills: This research area is inherently international in scope. The student will collaborate with partners in Europe, the USA and Australia, and share results at international conferences including the annual Meteoritical Society meetings. Upon completion the student will be equipped with skills that could lead to employment in areas such as space exploration, materials technology, or environmental management.

References

Daly, L., Lee, M., Bagot, P.A., Halpin, J., Smith, W., McFadzean, S., O’Brien, A.C., Griffin, S. and Cohen, B.E. (2020) Exploring Mars at the nanoscale: applications of transmission electron microscopy and atom probe tomography in planetary exploration. IOP Conference Series: Materials Science and Engineering 891, 012008.

King A. J., Daly, L. et al. 2022. The Winchcombe meteorite, a unique and pristine witness from the outer solar system. Science Advances 8: eabq3925.

Lee M. R., Lindgren P. and Sofe M. R. (2014) Aragonite, breunnerite, calcite and dolomite in the CM carbonaceous chondrites: high fidelity recorders of progressive parent body aqueous alteration. Geochim. Cosmochim. Acta 144, 126–156.