Detecting geomagnetic reversals: How low can you go?
Dr Greig Paterson, University of Liverpool
Prof Andy Biggin, University of Liverpool
- External Supervisors:
Dr Maxwell Brown, University of Iceland
Dr Greig Paterson, University of Liverpool, firstname.lastname@example.org
- CASE Partner:
Application deadline: 10 January 2020
One of the most dramatic shifts in Earth’s magnetic field is a polarity reversal, where the orientation of the field flips by 180 degrees. In recent geological time, reversals occur, on average, every couple of hundred thousand years and, as the field flips, its strength dramatically decreases. We know this from measurements of past geomagnetic fields preserved in the geological record, however there is still much to understand regarding the surface expression of field reversals. For example, Chou et al (2018) recently suggested reversals happen much quicker than previously thought – over a couple of centuries. In order to be able to understand geomagnetic field generation within the deep Earth we need to know how it behaves at Earth’s surface. This is not only of interest to Earth Scientists, but also of relevance to society as the present day geomagnetic field strength is decreasing has stimulated discussion as to whether we are currently heading towards a magnetic field reversal (see Brown et al 2018 and refs therein).
The project will focus on understanding what is the weakest possible field that we can measure, which is important not only for when the magnetic field is reversing, but also for identifying the earliest magnetic field, or when measuring meteorites to explore magnetic fields during solar system formation.Project Summary:
The success candidate will join the flourishing Geomagnetism research group (https://tinyurl.com/yypjard6), comprising ten other PhD students and post-docs. The group is supported by a multimillion-pound laboratory that is one of the best in the world for paleomagnetic intensity measurement and analysis.
The candidate will update and explore numerical simulations of paleointensity experiments to rapidly explore different methods and establish a set of testable predictions (Paterson et al. 2012). In turn, they will undertake a series of lab paleointensity experiments to ground-truth these predictions and determine the best approach for measuring weak fields.
They will demonstrate the practical applications of their work on mid Miocene (~13 Ma) lava flows from Iceland, which record a magnetic reversal. This fieldwork will be done in collaboration with co-supervisor Dr. Maxwell Brown (University of Iceland). They will apply the lessons and improvements derived from the laboratory experiments/simulations to obtain robust results from a period that can help us understand how Earth’s magnetic field works and what it might mean for the future of our protective magnetic shield.
The candidate will be fully trained in the experimental and computational aspects of the project, an aspect for which Liverpool is the world-leader. They will also have the opportunity to undertake microscope and rock magnetic characterization of the Icelandic samples, giving them a broad experience of Earth science magnetism.
This project would suit a geology or geophysics graduate who is keen to explore improving lab methods and undertake fieldwork to collect materials suitable for demonstrating their newly developed advances.References:
Brown, M., Korte, M., Holme, R., Wardinski, I., & Gunnarson, S. (2018). Earth’s magnetic field is probably not reversing. Proceedings of the National Academy of Sciences, 115(20), 5111-5116. doi:10.1073/pnas.1722110115
Paterson, G. A., A. J. Biggin, Y. Yamamoto, and Y. Pan (2012), Towards the robust selection of Thellier-type paleointensity data: The influence of experimental noise, Geochem. Geophys. Geosyst., 13, Q05Z43, doi: 10.1029/2012GC004046
Yu-Min Chou et al. Multidecadally resolved polarity oscillations during a geomagnetic excursion, Proceedings of the National Academy of Sciences (2018). doi: 10.1073/pnas.1720404115 the National Academy of Sciences (2018). doi: 10.1073/pnas.1720404115