Course goals
To understand the role of the Earth's ancient magnetic field as recorded in rocks in a wide range of Earth scientific disciplines. Examples include geodynamics & plate tectonics, time scales, geomagnetic variations and behaviour of the geodynamo through geological time, and application to (paleo) environmental magnetism and climate proxies.
Content
The paleomagnetism course deals with the integrated geophysical (geomagnetism, intensity of magnetic field), geochemical (rock magnetism, environmental magnetism), and geological (magnetostratigraphy and tectonic rotations) fundamentals of magnetism in Earth Sciences. Application of these techniques will be explained through practical assignments, hands-on exercises and data analyses.
Geophysical aspects: geomagnetic variations at all time scales. from secular variation, tiny wiggles and excursions of the field, to reversals (including magnetostratigraphy), reversal frequency, Superchrons and paleointensity reconstructions. At short time scales (100-5000 years), geomagnetic variations typically reflect core processes. Variations at longer time scales, however, must reflect mantle and core/mantle boundary processes. Hence, what do these variations tell us about processes in the internal, deep Earth?
Geochemical aspects: the magnetic carriers in rocks. How and why do rocks record the geomagnetic field? We discuss magnetism at the atomic level and link it to macroscopic properties of mineral and rock magnetism. We explain why the natural remanent magnetisation (NRM) can be geologically stable - i.e. for tens of billions of years, and how to extract this information from rock samples. This involves both laboratory and field tests, and we discuss how rocks acquire their NRM.
Geological aspects: stratigraphic and geodynamic applications: There are applications of paleomagnetism and rock magnetism in a wide range of earths scientific disciplines. Time Scales: the role of accurate dating is crucial in Earth Sciences, and, here, magnetostratigraphy forms a powerful part of the dating toolbox. It can be used in combination with other dating methods, of which astrochronology is the one providing the highest accuracy and precision. Applications of time scales have a wide range: from determining changes in (paleo)environment and (paleo)climate (and the corresponding influence on mineral magnetic changes in sediments) to dating tectonic phases and climate change, and their respective impacts on the geological archive. Geodynamic applications, from the scale of continents to regional studies: block rotations and crustal movement, paleomagnetic poles and apparent polar wander (APWP), hotspot versus paleomagnetic reference frames. In some case studies, there will be emphasis on the recognition of tectonic versus climatic processes in the development of sedimentary basins.
