DEEP down under: The potential for UK-Australian Palaeomagnetism to contribute to a new paradigm in deep Earth studies

Lead Research Organisation: University of Liverpool
Department Name: Earth, Ocean and Ecological Sciences

Abstract

This project will bring together two of the world's largest, most successful, and mutually distinctive palaeomagnetic groups to characterise the behaviour of Earth's ancient magnetic field and its link with deep Earth dynamics and evolution. Merging the complementary areas of expertise, sampling targets, and laboratory equipment available at Liverpool and Curtin promises to generate a novel longstanding collaboration with the potential to help revolutionise our understanding of Earth's deep interior.

The PI has a long term research plan to produce and use the first empirically-based quantitative models of palaeomagnetic field behaviour (palaeo-geomagnetism) back across billions of years of Earth history. The motivation for this is that these will provide a numerical framework for understanding the physics of the geodynamo process and how it has changed with Earth's evolution (including secular cooling of the core and mantle, inner core nucleation and growth, and changes in core-mantle heat flux resulting from mantle convection). These models will also allow assessments to made of the realism of numerical dynamo simulations (including those running under different boundary conditions representing different stages in Earth's evolution). Finally they will provide a tool for improving the constraints provided by measurements of the palaeomagnetic field on past continental reconstructions and tectonic processes (classical palaeomagnetism) - these currently rely on simplistic assumptions concerning the time-averaged field and its variability in time and space.

The PI has already secured substantial funding to build these models back to 750 million years ago and this project is designed to initiate a collaboration that will extend this endeavour firstly back to 1215 million years ago and then farther back into the Precambrian. In order to achieve this, we need to: (i) Obtain access to well-dated rocks from before 750 Ma that are reliable palaeomagnetic recorders to enable high quality full vector palaeo-geomagnetic records to be produced (ii) Initiate an intensive global measurement campaign to generate reliable data from such rocks that will constrain the statistical models of palaeo-geomagnetic field behaviour. (iii) Undertake collaborations with world-leading specialists in palaeogeography, classical palaeomagnetism and geodynamics to properly characterise Precambrian palaeo-geomagnetic field behaviour and exploit this information to improve our understanding of continental configurations at its surface and its relationship with deep Earth processes.

Our approach will be to utilise the wealth of resources (human, technical and geological) accessible to Curtin and to share the tools and knowledge of palaeo-geomagnetic technqiues developed at Liverpool such that a new antipodal centre of excellence in palaeo-geomagnetic field characterisation is initiated. During this project, we will: (i) undertake collaborative field sampling of Australian Precambrian rocks that are known to behave reliably and share extant samples; (ii) perform reciprocal visits to teach one another about our respective disciplines, obtain measurements at both institutions, share goals and results, and discuss future sampling targets and projects; (iii) use Proterozoic continental reconstructions to improve our global statistical field models and iterate to predict how reconstructions might change as a consequence of how the palaeomagnetic field varied. The outcomes of this project will answer exciting research questions and kick-start a major new collaboration in a timely manner to capitalise on existing NERC and other UK funding and leverage additional funds aimed at producing a new world leading direction in palaeo-geomagnetic research.

Planned Impact

The primary non-academic beneficiaries of the proposed research include:

1. Educational bases
2. The general public

Means by which they will benefit:

Both beneficiaries 1 and 2 will benefit from the fundamental advance in our understanding of the two main layers of our planet: (core and mantle) that we are aiming to make. Teachers, students, and the public at large are excited by fundamental unsolved problems such as the influence that processes, hidden deep within the Earth, can have on our daily lives. We are proposing to shed light on the processes responsible for the magnetic field that shields us from harmful solar wind radiation and mantle convection which dictates the forms of continents and the distribution of natural resources. If these findings can be properly communicated, society would gain from increased interest and engagement with the Earth sciences.

Dissemination methods:
Please see Pathways to Impact

Publications

10 25 50
 
Description We have performed measurements of the ancient magnetic field strength for several key time periods within the Neoproterozoic (1000 - 540 million years ago) and Palaeoproterozoic (2.5-1.6 billion years ago). These have shown the ancient field to display similar variability in strength as during the last few tens of millions of years ago indicating that a viable dynamo process was ongoing in Earth's possibly fully liquid core at these times.
Exploitation Route The primary aim of this project was to establish a long-term collaboration between our group and a leading group in Australia (Curtin University). This is ongoing and will see joint grant applications (one already submitted to ARC) and shared supervisory roles.
Sectors Education

 
Description Our research was showcased to up to 12,000 members of the general public at the Royal Society Summer Science Exhibition (1-7 July 2019) where adults and children learned about the Earth's magnetic field and the core dynamo process responsible for it.
First Year Of Impact 2019
Sector Education
Impact Types Societal

 
Description Collaboration with the Earth Dynamics Research Group at Curtin University, Western Australia 
Organisation Curtin University
Department Department of Earth and Planetary Science
Country Australia 
Sector Academic/University 
PI Contribution Louise Hawkins spent approximately 4.5 months at Curtin University training members of the geodynamics group who related to palaeomagnetism in palaeointensity techniques as well as to measure samples from the Yilgarn Craton. Louise Hawkins, along with Josh Beardmore from the Geodynamics group, continued these measurements back at Liverpool, including using the Microwave palaeointensity system that is unique to Liverpool. Louise Hawkins has written a paper based on the palaeointensity results from the 2.6Ga Yandiniling Dyke Swarm from the Yilgarn Craton that is close to submission. Andy Biggin, along with a Liverpool PhD student, also visited Western Australia for field work in the Pilbarra Craton.
Collaborator Contribution The Geodyanmics group provided all of the the initial pilot samples from studies they had performed on the Yilgarn Craton. The remaining samples came from two field trips facilitated by and including members of the Geodynamics group (as well as members from the Liverpool Geomagnetism group). The Geodynamics group also provided access to the Western Australia Palaeomagnetic and Rock-magnetic Facility for measuring the samples, which was done by Louise Hawkins and select members of the Geodynamics group. Two members of the group, Professor Zheng-Xiang Li and Josh Beardmore, also visited the Liverpool Geomagnetism lab to learn more about the palaeointensity method, the Liverpool Microwave system and continue the measuring.
Impact There is a paper on the on the palaeointensity results from the 2.6Ga Yandiniling Dyke Swarm from the Yilgarn Craton that is close to submission and the potential for future papers based on the initial results from some of the other localities studied. An ARC Discovery Project grant proposal was also submitted last month by Professor Zheng-Xiang Li with Andy Biggin as an investigator and Louise Hawkins as a named post-doc.
Start Year 2018
 
Description The Royal Society Summer Science Exhibition Stand 
Form Of Engagement Activity Participation in an activity, workshop or similar
Part Of Official Scheme? No
Geographic Reach National
Primary Audience Public/other audiences
Results and Impact "Magnetic to the Core" exhibition stand at the flagship public engagement event of The Royal Society in London, running for 7 days in July 2019. Approximately 12,000 visitors through the week for 22 exhibits. School parties came throughout the week and there were two black-tie soirees attended by policy makers. Our own impact assessment found a statistically significant increase in knowledge about Earth Science in those exhibition attendees that had visited our stand compared to those that had not; this knowledge gain was particularly high in those of school-age.
Year(s) Of Engagement Activity 2019
URL http://www.geomagnetism.org/?p=977