School of Geographical & Earth Sciences

Full details available at ‘Rain rain go away … come back another day’: Understanding Scotland’s changing relationships between climate change and mental health  – Scottish Graduate School of Social Science (sgsss.ac.uk) 

Xenoliths in carbonaceous chondrite meteorites as treasure troves of early Solar System history

Supervisors: Professor Martin Lee, Dr Sammy Griffin, Dr Luke Daly

Aims: This project will explore the dynamics and composition of our Solar System during its tumultuous birth ~4.5 billion years ago by studying fragments of highly primitive asteroids that are preserved as xenoliths in meteorites. The xenoliths were broken from their parent asteroids during catastrophic collisions, then moved through the protoplanetary disk to eventually be incorporated into other asteroids – it is pieces of these secondary asteroids that have fallen to Earth as meteorites. The xenoliths that they contain therefore preserve a record of asteroids that ‘lived fast and died young’ and as such can provide unique insights into the origin of our Solar System.

Context: Thousands of meteorites are available for study, the majority of which are from asteroids that orbit the Sun between Mars and Jupiter. The most primitive meteorites are the carbonaceous chondrites, which are derived from C-complex asteroids that populate the cold and dark outer reaches of the asteroid belt. One such meteorite fell in Winchcombe, Gloucestershire, in 2021 (O’Brien et al. 2022). The carbonaceous chondrites are of great interest because they contain primordial water and organic matter. Those meteorites that fell to Earth early in its history may therefore have bought with them a host of bio-essential compounds that eventually enabled life to evolve.

Despite their importance, carbonaceous chondrite meteorites are inherently limited in the information that can provide about early Solar System evolution. They are derived from the present-day population of asteroids and even then, meteorites can only be delivered to Earth from certain parts of the asteroid belt. In addition, only sufficiently tough rocks can survive the high pressures and temperatures of passage through Earth’s atmosphere. By contrast, xenoliths are fragments of asteroids that formed whilst the Solar System was very young but may have been long since destroyed, and they are protected from the rigours of atmospheric entry by their enclosing meteorite so that even the most fragile lithologies can survive (Nittler et al. 2019).

Objectives: Xenoliths are very abundant in some meteorites belonging to the CM group of carbonaceous chondrites (e.g., Lindgren et al. 2013). They can preserve a rich record of the geological history of their parent asteroids through assemblages of minerals including carbonates and phyllosilicates, and textures including mineral veins and compactional petrofabrics. Using these and other features of the xenoliths we will seek to understand how their parent asteroids evolved including evidence for the presence and flow of liquid water, and the extent to which they were deformed by impacts prior to breaking apart. During their transfer between asteroids the xenoliths have accreted finer grained material that was also free-floating in the protoplanetary disk, and bought it with them into the secondary asteroid. The xenoliths thus also serve as a form of ‘witness plate’, collecting and sampling a variety of materials that were present in the early protoplanetary disk.

Techniques, training and career prospects: The student will be trained to characterise the xenoliths and their host meteorites using an array of conventional tools (e.g., scanning electron microscopy, Raman spectroscopy, electron probe microanalysis, secondary ion mass spectrometry, transmission electron microscopy) and emerging analytical techniques (i.e., X-ray tomography, atom probe tomography and transmission Kikuchi diffraction). They will become part of a lively team of planetary scientists in Glasgow and will work within a vibrant research community in the UK and internationally. The student will have ample opportunity to travel widely in the UK and internationally in order to undertake research and present results. The student will gain subject specific and generic skills that can lead to employment in areas such as resource exploration, environmental management and space science.

Application procedure: The project is suitable for a graduate with a good honours degree in Geology or Earth Science with an interest in Planetary Science. There are two routes to apply for this PhD project.

If you have your own funding there is no deadline, and you can apply at https://www.gla.ac.uk/postgraduate/research/geology/.

This project may be eligible for a College of Science and Engineering Scholarship (available to UK, EU and International students). The application deadline is likely to be at the end of January 2024, and further details will be posted here: https://www.gla.ac.uk/schools/ges/research/postgraduate/

Please contact the principal supervisor with any questions (Martin.Lee@Glasgow.ac.uk).

References

Lindgren, P., Lee, M.R., Sofe, M.R. and Zolensky, M.E. (2013) Clasts in the CM2 carbonaceous chondrite Lonewolf Nunataks 94101: Evidence for aqueous alteration prior to complex mixing. Meteoritics & Planetary Science 48, 1074-1090.

Nittler, L. R., Stoud, R. M., Trigo-Rodríguez, J. M., De Gregorio B. T., Alexander C. M . O'D., Davidson, J., Moyano-Cambero, C. E., and Tanbakouei, S. (2019) A cometary building block in a primitive asteroidal meteorite. Nature Astronomy 3, 659–666.

O'Brien, A. C., Pickersgill, A., Daly, L., Jenkins, L., Floyd, C., Martin, P.-E., Hallis, L. J., King, A. and Lee, M. (2022) The Winchcombe Meteorite: one year on. Astronomy and Geophysics 63(1), 1.21-1.23.

Shocking details about the death of the dinosaurs from alkali feldspars

Supervisors: Martin Lee¹, Annemarie Pickersgill², Luke Daly¹

¹School of Geographical and Earth Sciences, University of Glasgow ²Scottish Universities Environmental Research Center, East Kilbride

Aims: The impact of a ~12 km diameter asteroid sixty-six million years ago caused one of the most devastating mass extinctions in Earth history. Many groups of plants and animals including the non-avian dinosaurs succumbed to a cascade of environmental changes following the event (Morgan et al. 2022). The ‘smoking gun’ of this impact is the 200 km diameter Chicxulub structure in Mexico, and detailed analysis of its rocks has revealed a wealth of information on the event itself and its effects on the Earth system. Fragments of alkali feldspars that were ejected into the Earth’s atmosphere from the shocked target rocks may have played a major role in post-impact climate change (Pankhurst et al. 2022). Given their potential importance, this project seeks to better understand how alkali feldspars respond to hypervelocity impacts through the analysis of Chicxulub, and other impact structures in the geological record.

Background: In 2016 the Chicxulub impact structure was drilled by IODP-ICDP Expedition 364 (Morgan et al. 2017). The target rock comprised carbonates and evaporites overlying a granitoid basement (Feignon et al. 2021). The basement lithologies experienced pressures of ~16–18 GPa, with most minerals showing evidence for shock deformation. Alkali feldspar is abundant in the basement granite but its response to the impact has received less attention than other common rock-forming minerals. Given that the structure has been so intensively studied, Chicxulub therefore offers an excellent opportunity to characterise the impact deformation of alkali feldspar including the nature of shock-formed microstructures, and any associated chemical and isotopic alteration. Another very important reason for focusing on alkali feldspar is that it is highly effective in nucleating clouds (Harrison et al. 2016) and so may play a major role in the environmental repercussions of impact events (Coldwell et al. 2019; Pankhurst et al. 2017, 2022).

Objectives: This project will characterise the mineralogy, microstructure and chemical/isotopic composition of alkali feldspars from the Chicxulub granite together with samples from other impact structures (e.g., Ries in Germany and Rochechouart in France), and unshocked granites for comparison. This project will use conventional imaging and microanalysis techniques (e.g., scanning electron microscopy, electron probe microanalysis) together with specialist tools for characterising microstructures over length scales from millimetres (electron backscatter diffraction) to nanometres (transmission Kikuchi diffraction, transmission electron microscopy, atom probe tomography). The outcome of this work will be a new understanding of the response of alkali feldspars to hypervelocity impacts, and how such shock deformation may affect their role in environmental change.

Training, and career prospects: The student will be trained in petrology, mineralogy and geochemistry, and will be part of a lively team of planetary scientists in Glasgow. There will be ample opportunity to travel widely in the UK and internationally in order to undertake research and present results. After graduation the student could work in areas such as space science, environmental management or materials science

Application procedure: The project is suitable for a graduate with a good honours degree in Geology or Earth Science. There are two routes to apply for this PhD project. If you have your own funding there is no deadline, and you can apply at https://www.gla.ac.uk/postgraduate/research/geology/. Please contact the principal supervisor with any questions (Martin.Lee@Glasgow.ac.uk). This project may be eligible for a College of Science and Engineering Scholarship (available to UK, EU and international students). The application deadline is likely to be at the end of January 2024, and further details will be posted here: https://www.gla.ac.uk/schools/ges/research/postgraduate/.

References

Coldwell, B.C. and Pankhurst, M.J. (2019) Evaluating the influence of meteorite impact events on global potassium feldspar availability to the atmosphere since 600 Ma. Journal of the Geological Society 176, 209–224.

Feignon, J.-G., de Graaff, S. J., Ferrière, L., Kaskes, P., Déhais, T., Goderis, S., Claeys, P. and Koeberl, C. (2021), Chicxulub impact structure, IODP-ICDP Expedition 364 drill core: Geochemistry of the granite basement. Meteoritics and Planetary Science 56, 1243–1273.

Harrison, A.D., Whale, T. F., Carpenter, M. A., Holden, M., Neve, L., O'Sullivan, D., Vergara Temprado, J. and Murray, B. J. (2016) Not all feldspar is equal: a survey of ice nucleating properties across the feldspar group of minerals. Atmospheric Chemistry and Physics Discussions, 1–26.

Morgan, J.V., Bralower, T.J., Brugger, J. et al. (2022) The Chicxulub impact and its environmental consequences. Nature Reviews Earth and Environment 3, 338–354.

Morgan J., Gulick S., Mellet C.L., Green S. L., and Expedition 364 Scientists. (2017) Chicxulub: Drilling the K-Pg impact crater. Proceedings of the International Ocean Discovery Program, 364. College Station, Texas: International Ocean Discovery Program. 164 p.

Pankhurst, M.J., Stevenson, C J. and Coldwell, B.C. (2022) Meteorites that produce K-feldspar-rich ejecta blankets correspond to mass extinctions. Journal of the Geological Society 179.

Pankhurst, M.J. (2017) Atmospheric K-feldspar as a potential climate modulating agent through geologic time. Geology 45, 379–382.