Subduction zones are arguably the most significant tectonic features on Earth as they are the main driver of plate motion and mantle flow, and they play a dominant role in shaping the Earth’s topography through formation of mountain belts and ocean basins, thereby affecting atmospheric and ocean circulation, causing long-term climate change. Furthermore, they are associated with many different types of mineral deposits and with sedimentary basins that can be used for geothermal energy extraction and/or carbon capture and storage (CCS). Lastly, subduction zones produce the most destructive volcanoes and earthquakes (and related tsunami) on Earth, including the December 2004 Sumatra-Andaman earthquake and March 2011 Japan earthquake. Therefore, there is both a scientific and societal need to increase our understanding of subduction zone processes. Our group investigates both generic subduction zone processes, specific subduction zones found at various locations across the globe, as well as settings of former subduction that have evolved into collision zones or continental subduction zones.
Geodynamics & plate tectonics
We particularly use geodynamic models to provide quantitative insight into subduction zone processes, mantle flow and orogenesis. We use both scaled laboratory modelling (analogue modelling) and numerical modelling techniques to investigate these processes. The analogue experiments are carried out in the Kuenen-Escher Geodynamics Laboratory (KEG Lab), which houses a variety of equipment (e.g. rheometer, density meter) to assess the physical properties of the modelling materials, modelling tanks and sandboxes to run the experiments, and cameras and a Particle Image Velocimetry (PIV) System to record, visualize, quantify and post-process the experiments.
For the numerical modelling we use the open source code Underworld, which has been developed at Monash University, The Australian National University and the University of Melbourne in Australia by Louis Moresi and colleagues. This is a particle-in-cell finite element code that has been specifically designed to simulate the evolution of large-scale geodynamic processes in three-dimensional space.
Main topics of research:
- Subduction zone evolution and subduction-induced mantle flow (example).
- Cordilleran mountain building at subduction zones (e.g. Andes).
- Backarc basin formation at subduction zones (e.g. Aegean Sea).
- Continental subduction and orogenesis (e.g. Himalaya, Tibet and East Asia).
- Dynamic topography and (past) subduction (e.g. Australia).
- Subduction termination, ophiolite obduction (e.g. New Guinea).
- Subduction initiation (e.g. Scotia Sea).
- Subduction zone forearc topography (example)
1.2. Tectonic plates in extension
Extension of tectonic plates is controlled by the interplay between diverging forces that exert tension on a tectonic plate and forces in the mantle (e.g. mantle upwelling) that cause heating of the tectonic plate that experiences tension. If a tectonic plate is under extension for an extended period of time, the surface expression will show basins and depressions in various sizes, shapes and depth. These depressions will initially fill with water and sediments. Continuous extension over millions of years will lead to extreme thinning of a plate causing it to break-apart, forming an oceanic spreading centre where new crust is formed.
At the VU, we investigate how plates with different rheological compositions evolve when they are extending. We do this by participating in geophysical and geological data acquisition expeditions with international partners. We use numerical and analogue modelling techniques to simulate and quantify how plates in extension behave and we perform field work to understand the geological conditions of extending tectonic plates.
Main topics of research:
- Active rift- and spreading systems (e.g. East African Rift)
- Failed rift and aborted extensional systems (e.g. North Sea)
- Passive margins (e.g. South Atlantic margins)
- Mid-Ocean Ridges and Transform systems (e.g. Mid-Atlantic Ridge)
- Back-arc basins (e.g. Lau Basin, Scotia Sea, Aegean Sea)