Hydrodynamic modelling of some metamorphic processes

The P–T paths for metamorphic complexes from the Precambrian shields and fold belts of different ages may result from advection, i.e. one-cycle convective processes in the lithosphere. This conclusion has been exemplified by the metamorphic evolution of several well-known complexes, for which an advective model can be successfully applied. Numerical simulations of the above processes in terms of Newtonian rheology by using a two-dimensional finite element program have been conducted.
Two representative models for intracontinental gravitational ordering initiated presumably by mantle activity are considered: (i) a thermally activated multi-layered rhythmic sequence and (ii) huge rising diapiars causing circulation, in which crustal lithologies underwent high- P metamorphism (above 10–15 kbar) and subsequent ascent toward the Earth's surface.