How strong is the memory of the geomagnetic field? A critical appraisal of reversal asymmetry in precambrian rocks of Scotland
Lead Research Organisation:
University of Liverpool
Department Name: Earth Surface Dynamics
Abstract
The Earth's magnetic field reverses its polarity such that after a reversal magnetic compasses point in the opposite geographical direction. This has occurred repeatedly throughout geological time. In general, reversals of the field are anti-parallel and the directions of magnetisation before and after a reversal lie at 180 degrees to each other. However, there are now several cases where the directions of magnetisation recorded in rocks indicate that a series of reversal may not have been anti-parallel. These observations might be the products of several magnetisation events and in these circumstances the directions reflect different parts of the geological history of the sampling site and not unusual behaviour of the field. This project is designed to test if ancient magnetisations have recorded such unusual behaviour. As with many other natural systems atypical behaviour (e.g. illness) can be as informative as the normal state. Thus, these results may lead to a greater understanding of how the Earth's field behaves and has evolved.
Organisations
| Description | There is very strong evidence that over the last 2000 million years the Earth's magnetic field has frequently reversed it's polarity such that the north magnetic pole switched geographical position with the southern magnetic pole. This research has shown that over an interval of say 30 million years (approximately 1000 million years ago) the Earth's magnetic field reversed its polarity several tens of times but instead of the poles occupying positions 180 degrees apart they lay at 140 degrees apart; a phenomenon described as an asymmetrical reversal. Asymmetrical reversals are not restricted to this time interval and they provide information on the behaviour of the magnetic from which the source and stability of the Earth's magnetic field may be understood. During asymmetric reversals the Earth's magnetic field is acting an unusual or atypical way and this can provide information on its origins just as some diseases and occupational illnesses allowed physicians in the 19th century to determine the functions of many organs. |
| Exploitation Route | The data an observations can be used to test and constrain mathematical models of the behaviour of the Earth's magnetic field |
| Sectors | Education |
| Description | The findings have been reported at several discipline related research meetings. The Search for Latent Components of Magnetisation in Late Precambrian Sediments of Northwest Scotland. Abstract, Magnetic Relaxation Research Meeting, Liverpool, 2012. Joint paper with Professor R.T. Holme, University of Liverpool. Are All Reversals Symmetric? The Search for Latent Components of Magnetisation in Late Precambrian (Torridonian) Sediments of Northwest Scotland. Abstract, European Geoscience Union, Vienna, 2012. Joint paper with Professor R.T. Holme, University of Liverpool Are All Reversals Symmetric? Non-anti-parallel reversals from the late Precambrian. Abstract, Symposium on the Study of the Earth's Deep Interior, Leeds 2012. Joint paper with Professor R.T. Holme, University of Liverpool. As defined in the notes this research has had no impact beyond academia though, it has been included in Engagement Activities |
| First Year Of Impact | 2012 |
| Sector | Education |
| Description | Liverpool Geological Society Monthly Meeting |
| Form Of Engagement Activity | A talk or presentation |
| Part Of Official Scheme? | No |
| Geographic Reach | Local |
| Primary Audience | Public/other audiences |
| Results and Impact | Lively and thoughtful discussions followed None |
| Year(s) Of Engagement Activity | 2014 |
| Description | Scibar talk (Knutsford) |
| Form Of Engagement Activity | A talk or presentation |
| Part Of Official Scheme? | Yes |
| Geographic Reach | Regional |
| Primary Audience | Public/other audiences |
| Results and Impact | Lively and thoughtful discussions None |
| Year(s) Of Engagement Activity | 2011 |
| Description | U3A Group of the Royal Astronomical Society |
| Form Of Engagement Activity | A talk or presentation |
| Part Of Official Scheme? | Yes |
| Geographic Reach | Regional |
| Primary Audience | Public/other audiences |
| Results and Impact | Lively and thoughtful discussions followed None |
| Year(s) Of Engagement Activity | 2011 |