Palaeomagnetic records may be unique in the Earth sciences in giving us direct observational evidence regarding deep internal processes occurring back into deep geological time. The Earth's magnetic field exhibits clear variations on timescales of millions and even billions of years that are probably caused by changing conditions in the planet's core and mantle. I am interested to try and explain these variations in terms of mantle dynamics and core evolution. I hope to develop palaeomagnetism into a reliable tool for telling us, not only about fluid flow in the outer core, but also about mantle convection from the bottom-up through documenting and interpreting its influence on the geodynamo.
Selected publications:
Biggin, A.J., Piispa, E, Pesonen, L.J., Holme, R., Paterson, G.A., Veikkolainen, T.,, Tauxe, L. 2015. Palaeomagnetic field strength variations suggest Mesoproterozoic inner core nucleation. Nature. 526, 245-248.
Biggin, A.J. , Steinberger, B., bert, J., Suttie, N., Holme, R., Torsvik, T., van der Meer, D., vanHinsbergen, 2012. Possible links between long term geomagnetic variations and whole-mantle convection processes. Nature Geosci. 8, 526-533.
Biggin, A.J., Strik, H.M.A., & Langereis, C.G., 2008. Evidence for a very-long-term trend ingeomagnetic secular variation. Nature Geosci. 1, 395-398.
A plot of the strength of the main component of the geomagnetic field versus time for the last few thousands of years. Taken from Ertepinar et al. (2012).
The geomagnetic field's strength and morphology has varied considerably even on the timescales of human history. The field is presently weakening at a rate of a few percent per century leaving our technology increasingly vulnerable to harsh space weather events. Studies of recent variations can tell us about the dynamics of the geodynamo processes operating the Earth's core and additionally warn us about how the field may change in the near future. I am particularly interested in studying very strong fluctuations in the strength of the field that are increasingly evident in archaeomagnetic records from the last few thousands of years.
Selected publications:
Ertepinar, P., Langereis, C.G., Biggin, A.J., de Groot, L.V., Kulakoglu, F., Omura, S., Süel, S. 2016. Full vector archaeomagnetic records from Anatolia between 2400 and 1350 BCE: Implications for geomagnetic field models and the dating of fires in antiquity. Earth Planet. Sci. Lett. 434, 171-186.
Ertepinar P, Langereis CG, Biggin AJ, Frangipane M, Matney T, Okse T, Engin A (2012) Archaeomagnetic study of five mounds from Upper Mesopotamia between 2500 and 700 BCE: Further evidence for an extremely strong geomagnetic field ca.3000 years ago'. Earth Planet. Sci. Lett. 357-358, 84-98.
de Groot L, Biggin A, Dekkers M, Langereis C, Herrero-Bervera E (2013). Rapid regional perturbations to the recent global geomagnetic decay revealed by a new Hawaiian record. Nature Communications 4: 2727.
Some of the oldest rocks on Earth retain a palaeomagnetic signal that can be demonstrated to be as old as they are. The Earth was a very different place 3.5 billion years ago, when the rocks we are working with from the Barberton Greenstone Belt in southern Africa acquired their magnetisations. We know very little but the mantle was much hotter and the core was probably still entirely liquid. Palaeomagnetic studies of these rock provide a unique opportunity to constrain conditions deep in Earth's interior in the Archaean Aeon and thereby to document our planet's evolution.
Selected publications:
Biggin, A.J., de Wit, M.K., Langereis, C.G., Zegers, T.E., Voûte, S., Dekkers, M.J., Drost, K., 2011. Palaeomagnetism of Archaean rocks of the Onverwacht Group, Barberton Greenstone Belt (southern Africa): Evidence for a stable and potentially reversing geomagnetic field at ca. 3.5 Ga. Earth Planet. Sci. Lett. 302, 314-328.
Biggin, A.J., Strik, G.H.M.A. & Langereis, C.G., 2009. The intensity of the geomagnetic field in the late-Archaean: new measurements and an analysis of the updated IAGA palaeointensity database. Earth, Planets & Space 61, 9-22.
The Barberton Greenstone Belt - home to some of the oldest palaeomagnetic recorders on the planet.
Outputs of a numerical model of thermoremanent magnetisation applied to predict the outcome of different palaeointensity experiments performed on non-ideal samples (Biggin et al., 2010).
Measurements of the ancient geomagnetic strength are crucial for documenting and understanding geomagnetic field behaviour on all timescales. It is possible to make these "palaeointensity" measurements only from things that have cooled down from high temperature in the presence of the geomagnetic field and acquired a "thermoremanent magnetisation". The process by which rocks acquire this magnetisation is not fully understood however and this, plus the fact that many rocks do not contain ideal magnetic recorders, makes measuring the palaeointensity accurately difficult. I am interested to understand the thermoremanent magnetisation acquisition process and the different problems that can bias palaeointensity estimates so they can be mitigated against.
Selected publications:
Paterson, G.A., Biggin, A.J., Hodgson, E., Hill, M.J., 2015. Thellier-type paleointensity data from multidomain specimens. Phys. Earth Planet. Int. 245, 117-133.
Biggin AJ, Badejo S, Hodgson E, Muxworthy A, Shaw J, Dekkers M, 2013. The effect of cooling rate on the intensity of thermoremanent magnetisation (TRM) acquired by assemblages of pseudo-single domain, multi domain, and interacting single domain grains. Geophysical Journal International 193, 1239-1249
Biggin, A.J., 2010. Are systematic differences between thermal and microwave Thellier-type palaeointensity estimates a consequence of multidomain bias in the thermal results? Physics of the Earth and Planetary Interiors, 180: 16-40.
Secular variation refers to the changes in the Earth's magnetic field that require you to change your compass's north arrow every year or two. It is also thought to be responsible for causing the magnetic field to reverse its polarity every few hundreds of thousands of years. Palaeosecular variation is the study of this variability as recorded in ancient lavas and sedimentary rocks and it has the potential to provide fundamental insights into the stability state of the geodynamo in the past as well as provide a tool for constraining volcanic eruption rates.
Selected publications:
Suttie, N., Biggin, A.J., Holme, R., 2015. Robust estimators of palaeosecular variation. Geophys. J. Int. 200, 1046-1051.
Suttie, N., Biggin, A.J., Holme, R., 2014. Correlation of palaeomagnetic directions constrains eruption rate of large igneous provinces. Earth Planet. Sci. Lett. 387, 4-9.
Biggin, A.J., Van Hinsbergen, D.J.J., Langereis, C.G., Straathof, G.B. and Deenen, M.H.L., 2008. Geomagnetic secular variation in the Cretaceous Normal Superchron and in the Jurassic. Phys. Earth Planet. Inter. 169, 3-19.
Palaeosecular variation represented in terms of scatter of virtual geomagnetic poles in the Cretaceous Normal Superchron (Biggin et al., 2008; PEPI).