Mantle dynamics

While mantle convection is generally accepted as the underlying cause of plate motions, the geometry of mantle flow and its relation to plate motions remains poorly understood. Researchers at NGU's Center for Geodynamics aim at improving mantle flow models by using observational, and experimental constraints, and through using more sophisticated modeling procedures.

Dynamic topography 

Mantle flow models predict the mantle contribution to surface uplift and subsidence over time on a large scale. Dynamic topography thus influences which regions are below sea level, and therefore where sediments and related natural resources may form. Predictions may be combined with topographic changes from crustal and lithospheric processes and compared with observational constraints based on thermochronology and field geology.

Lowermost mantle

The relation between seismic velocity, temperature and composition in the lowermost mantle is studied. This is important for understanding heat flow from the core, and generation of Earth's magnetic field.

Figure illustrating link between plate reconstructions and the deep Earth. It shows that both many reconstructed eruption sites of Large Igneous Provinces (white dots) and hotspots (red crosses) fall above a region close to the -1% contour of seismic velocity anomalies in the lowermost mantle. Hence, we suggest that this region marks a "plume generation zone".

The mantle reference frame

A key ingredient in the link between plate motions and mantle processes is the relation between their reference frames. These may be based on hotspot tracks or paleomagnetism. In particular, plate motions relative to the mantle need to be distinguished from true polar wander (motion of the entire Earth relative to its spin axis).