Understanding the complex magnetic records in natural materials requires knowledge of the fundamental magnetic properties of their minerals. We investigate the common terrestrial magnetic minerals, including iron sulphides, iron oxides, iron-titanium oxides, that have origins from either chemical precipitation, biological synthesis or environmental weathering. Studies range from atomic-scale magnetic mineral structures to macro-scale fundamental rock magnetic properties.
“Fundamental rock and mineral magnetism” Read More
Magnetic proxies are widely used in paleoenvironmental reconstructions. However, traditional environmental magnetic approaches rely heavily on simple magnetic parameters and their ratios. We take a different approach: we determine magnetic property variations from direct observation of magnetic minerals, and combine these with advanced rock magnetism, mathematical unmixing, and magnetic modelling. This helps to get more robust magnetic proxies for tracing environmental processes.
“Paleoenvironmental and paleoclimate reconstructions” Read More
Investigating DRM/PDRM/CRM processes to understand how marine sediments get magnetized. We use a combined experimental and numerical approach: we do laboratory redeposition experiments under controlled conditions, and also build numerical models in order to get a better picture of the magnetic recording processes in marine sediments.
We use a full finite-element micromagnetic model (MERRILL
) to simulate the magnetic properties of complex magnetic mineral ensembles, such as biogenic magnetite/magnetotactic bacteria and magnetic mineral inclusions in silicates, that are widely present in many natural environments. We seek to link the simulation with experimental data to detect subtle changes reflected in magnetic proxies throughout sedimentary records.
“Micromagnetic modelling” Read More
This is a new technique where we collect samples from large tsunami boulders (recently from Cape Verde) that were quarried and rotated during the tsunami. Afterwards they slowly acquire a viscous remagnetization whose intensity/blocking temperature increases over time. By measuring this viscous remagnetization, we can calculate the age of the tsunami.
We use first-order reversal curve (FORC) diagrams to understand mixtures of different minerals and different domain states present in a sample. This is done both with numerical models and experimentally on ocean sediments to understand how different minerals vary in response to environmental factors.
“Unmixing complex mineralogies / domain-states” Read More