A selection of fossilized micrometeorites that fell to Earth during the Cretaceous. Having reacted with the Earth’s atmosphere they provide a window into the atmospheric conditions ~87 million years ago.
Micrometeorites are tiny grains of meteoritic dust typically <1mm in size that originate from asteroids and comets.
These micrometeorites have been falling to Earth throughout its 4.6 billion year history and are preserved continuously within the geological record.
Their study directly complements studies of meteorites looking to unravel the geological diversity of early solar system materials, whilst also providing direct insights of how the the flux of 'cosmic dust' to Earth from the inner solar system has changed with time.
Importantly, because micrometeorites interact with the atmosphere as they fall to Earth they represent an atmospheric proxy, facilitating research into the evolution of Earth’s atmosphere over geological time. This is an emerging 'hot topic' in planetary science whose results are pertinent to the current climate crisis.
Background
To help develop micrometeorites as an atmospheric proxy, samples will be extracted from rocks of geological periods that reflect dramatic changes to Earth’s atmosphere and global climate.
For example, the evolution of land plants during the mid-Palaeozoic resulted in the removal of atmospheric CO2 and increases in O2. These climatic changes will be observable in fossil micrometeorites by exploring the extent of mineralogical change through oxidation of FeNi metal to phases such wüstite (FeO), magnetite (Fe3O4) and hematite (Fe2O3).
By comparing the degree of oxidation in ancient micrometeorites from key time periods to the oxidation extent observed in modern particles, a climate proxy can be developed that is capable of tracing the oxidation extent of the atmosphere and indirectly the abundance of CO2 and O2.
In order to maximise the scientific potential of micrometeorites, the effects of fossilization and diagenesis on these tiny extraterrestrial particles must be modelled and quantified. Within this project micrometeorites will be identified and extracted from a range of modern and ancient sediments providing a direct measure of changes in the flux of extraterrestrial dust to Earth over geological time.
Moreover, a model for quantifying the extent of diagenetic alteration of micrometeorites will then be developed by chemically analysing micrometeorites and their host sediments as well as the fossil micrometeorites.
The Natural History Museum houses the National Meteorite Collection, a comprehensive and systematic collection that is foundational for UK planetary science.
Within this is a growing collection of ancient and modern micrometeorites that will be used as a key resource for this study. Furthermore, the museum is uniquely positioned for such a study on micrometeorites with its extensive internationally significant geological, micropaleontological and ocean bottom sediment collections.
Career development
The student will benefit from being part of a strong collaborative team of students, curators and researchers with multidisciplinary backgrounds.
Our research teams and supervisors have a strong track record of successfully working together on similar projects. Studying at the Natural History Museum and the Open University will provide access to a huge range of complementary laboratory facilities and extensive opportunities for outreach and public engagement.
State-of-the-art 2D and 3D imaging and analysis techniques that provide an array of chemical, spectroscopic, mineralogical, isotope and synchrotron information will be obtained both in house and at international science facilities. Correlating these analyses will provide a unique insight into the mineralogy of micrometeorites and their application to monitoring climate change.
The successful candidate will perform all experiments, learning to independently operate a wide range of analytical techniques whilst developing transferable skills in stable isotope geochemistry, mineralogy, and numerical modelling.
A STEM PhD is a good stepping stone for a career in academia, government policy, industrial research, science communication, museum curation, scientific publishing or the UK space sector. This project would suit a candidate excited by meteoritics, climate change and atmospheric evolution, with a background in geological or environmental sciences, physics or a related subject.
How to apply
Please apply online on the Natural History Museum’s careers portal and fill in the application form.
Please include:
- CV
- Covering letter outlining your interest in the PhD position, relevant skills training, experience and qualifications for the research.
- A statement of how this PhD project fits your career development plans
- Two academic references
Application deadline: 28 February 2022
Apply for this course
Application deadline: 28 February 2022
Supervisors
Natural History Museum, London
Paul Schofield, Sara Russell, Natasha Almeida
Open University
Kent University
Suggested reading
Suttle, M.D., Hasse, T., Hecht, L. (2021) Evaluating urban micrometeorites as a research resource - a large population collected from a single rooftop. Meteoritics and Planetary Science 56 (811) pp. 1531-1555.
Fischer, M.B., Oeser, M., Weyer, S., Folco, L., Peters, S.T., Zahnow, F. and Pack, A., 2021. I‐Type Cosmic Spherules as Proxy for the Δ′ 17O of the Atmosphere - a Calibration With Quaternary Air. Paleoceanography and Paleoclimatology, 36(3), p.e2020PA004159.
Huang, G., Eager, J.K., Mayne, N.J., Cui, D., Manners, J., Hebrard, E., Liu, Z. and Lenton, T.M., 2021. CO2 and O2 oxidized 2.7 Ga micrometeorites in two stages suggesting a> 32% CO2 atmosphere. Precambrian Research, 366, p.106423.
Suttle, M.D, Genge, M.J (2017) Diagenetically altered fossil micrometeorites suggest cosmic dust is common in the geological record. Earth and Planetary Science Letters. V 476, 132-142
Larsen J. (2017) In Search of Stardust: Amazing Micrometeorites and Their Terrestrial Imposters. Voyageur Press, 152pp