PD Dr. Florian Lhuillier

Research Interests

The Earth’s magnetic field (EMF), schematically described by a geocentric axial dipole, is generated by a self-sustaining dynamo in the Earth’s outer core. My research focusses on understanding (i) how the key features of the EMF—polarity, direction and strength—varied over diurnal to multi-million-year timescales, (ii) how the records of the EMF are preserved in volcanic and baked rocks, and (iii) how a good knowledge of the EMF can help to better constrain geological processes or archaeological events.

Vergrößern

Describing the changes of the Earth’s magnetic field over geologic time

During the past 200 Myr, the frequency of geomagnetic polarity reversals fluctuated from zero during the Cretaceous Normal Superchron (84–121 Ma) to more than ten per million years during the Jurassic hyperactivity event (155–171 Ma). At the same time, the EMF fluctuated in direction and strength. Through the analysis of the magnetic record of volcanic rocks collected from monogenetic volcanic fields (such as Vogelsberg, Lausitz and Hocheifel in Germany) or large igneous provinces (such as the Ethiopian or the Madagascan Traps), we seek the existence of correlations between reversal frequency, directional fluctuations, and dipole strength. Such investigations aim at answering the fundamental question whether the Earth’s dynamo changed its modus operandi through geological time.

Running projects

• Behaviour and characterisation of the geodynamo at the end of the Cretaceous Normal Superchron” (DFG grant 521315821, 2024–2027)
• Palaeomagnetism of tertiary volcanic rocks from Germany” (DFG grant 517539177, 2023–2026)

Lhuillier, F., Lebedev, I. E., Tikhomirov, P. L., & Pavlov, V. E. (2025). Is the Geodynamo Characterized by a Distinct Geomagnetic Secular Variation Regime During the Cretaceous Normal Superchron? Journal of Geophysical Research: Solid Earth, 130(4), e2024JB030928. 10.1029/2024jb030928

Lhuillier, F., Shcherbakov, V. P., & Sycheva, N. K. (2023). Detecting dipolarity of the geomagnetic field in the paleomagnetic record. Proceedings of the National academy of Sciences of the United States of America, 120(25), e2220887120. 10.1073/pnas.2220887120

Vergrößern

Understanding the thermochemical remanence acquisition in volcanic rocks

The volcanic rocks, the iron oxides of which ideally acquire a thermoremanent magnetisation during their initial cooling, are essential to reconstruct the history of the geomagnetic dipole strength over geological time. However, magneto-mineralogical transformations occurring during or after the emplacement of the rocks give rise to various types of thermochemical remanent magnetisations. Through thermomagnetic experiments, microscopic observations, structural analyses and theoretical considerations, we investigate the conditions leading to the preservation or alteration of the palaeomagnetic record. Identifying such conditions is essential for a robust interpretation of the absolute palaeointensity database.

Shcherbakov, V. P., Lhuillier, F., Gribov, S. K., Tselmovich, V. A., & Aphinogenova, N. A. (2024). Potential Bias in Volcanic Paleomagnetic Records Due To Superimposed Chemical Remanent Magnetization. Geophysical Research Letters, 51(12), e2024GL109630. 10.1029/2024gl109630

Shcherbakov, V. P., Lhuillier, F., & Sycheva, N. K. (2021). Exact analytical solutions for kinetic equations describing thermochemical remanence acquisition for single‐domain grains: Implications for absolute paleointensity determinations. Journal of Geophysical Research: Solid Earth, 126, e2020JB021536. 10.1029/2020jb021536

Vergrößern

Extracting the geomagnetic signal from baked clays or sandstones

Human-produced baked clays (bricks, potteries, kilns) are precious records of the Earth’s magnetic field over the past millennia. If dated by archaeologists, they can be used to construct local reference curves, extending the records of geomagnetic observatories. Such local reference curves can be used in turn for archaeomagnetic dating. By analogy, fine-grained sediments baked by intrusions or lavas are alternatives to volcanic rocks to determine the strength of the Earth’s magnetic field over geological time. We aim to collect such baked sediments throughout the world to densify the absolute palaeointensity database, with a particular focus on field strength during the Cretaceous Normal Superchron.

Chi, Y., Lhuillier, F., Meng, J., Zhang, C., & Shcherbakov, V. P. (2025). Geomagnetic Dipole Strength During the Cretaceous Normal Superchron Recorded by Baked Sediments From Hainan (SE Asia). Geophysical Research Letters, 52(17), e2025GL116894. 10.1029/2025gl116894

Hervé, G., Chauvin, A., Lanos, P., Lhuillier, F., Boulud-Gazo, S., Denti, M., & Macario, R. (2021). How did the dipole axis vary during the first millennium BCE? New data from West Europe and analysis of the directional global database. Physics of the Earth and Planetary Interiors, 315, 106712. 10.1016/j.pepi.2021.106712

Vergrößern

Constraining the eruptive history of large igneous provinces

Large igneous provinces, ascribed to the impingement of mantle plumes on the lithosphere, are responsible for the massive outpouring of several million km3 of basaltic lava over a few million years, with notable consequences on the biosphere due to the sudden release of gas in the atmosphere or in the hydrosphere. Each lava flow constituting an instantaneous record of the Earth’s magnetic field, a flow-by-flow study of the palaeomagnetic record provides temporal constraints on the eruptive history of the large igneous province. On the one hand, the obtained polarities can be compared with the geomagnetic polarity timescale, yielding an estimate of the eruption rate. On the other hand, the detection of serial correlation in the palaeomagnetic directions helps to detect the existence of eruptive pulses.

Eid, B., Lhuillier, F., Gilder, S. A., Pfänder, J. A., Gebru, E. F., & Aßbichler, D. (2021). Exceptionally High Emplacement Rate of the Afar Mantle Plume Head. Geophysical Research Letters, 48(23), e2021GL094755. 10.1029/2021gl094755

Lhuillier, F., & Gilder, S. A. (2019). Palaeomagnetism and geochronology of Oligocene and Miocene volcanic sections from Ethiopia: geomagnetic variability in the Afro-Arabian region over the past 30 Ma. Geophysical Journal International, 216(2), 1446-1481. 10.1093/gji/ggy517

Vergrößern

Modelling the dynamo process in the Earth’s outer core

The thermochemical convection of an electrically conducting iron-nickel alloy in the Earth’s fluid outer core is responsible for the generation of the main geomagnetic field. By using the equations of the magnetohydrodynamics and making some approximations, sequences of several tens of million years can be numerically simulated. These simulations allowed us for instance to produce predictions on the distribution of the length of the polarity chrons, on the duration of the polarity reversals, or on the morphology of the field during such events.

Lhuillier, F., Hulot, G., Gallet, Y., & Schwaiger, T. (2019). Impact of inner-core size on the dipole field behaviour of numerical dynamo simulations. Geophysical Journal International, 218, 179-189. 10.1093/gji/ggz146

Lhuillier, F., Hulot, G., & Gallet, Y. (2013). Statistical properties of reversals and chrons in numerical dynamos and implications for the geodynamo. Physics of the Earth and Planetary Interiors, 220, 19-36. 10.1016/j.pepi.2013.04.005

Publikationsliste