Plate eduction is a geodynamic process characterized by normal-sense
coherent motion of previously subducted continental plate. This
mechanism may occur after slab detachment has separated the negatively
buoyant oceanic plate from the positively buoyant orogenic root.
Eduction may therefore be partly responsible for exhumation of high
pressure rocks and late orogenic extension. We used two-dimensional
thermomechanical modeling to investigate the main features of the plate
eduction model. The results show that eduction can lead to the quasi
adiabatic decompression of the subducted crust (approximate to 2 GPa) in
a timespan of 5 My, large localized extensional strain in the former
subduction channel, flattening of the slab, and a topographic uplift
associated with extension of the orogen. In order to further investigate
the forces involved in the eduction process, we ran systematic
parametric simulations and compared them to analytic plate velocity
estimations. These experiments showed that eduction is a plausible
mechanism as long as the viscosity of the asthenospheric mantle is lower
than 10(22) Pa.s while subduction channel viscosity does not exceed
10(21) Pa.s. We suggest that eduction can be a viable geodynamic
mechanism and discuss its potential role during the orogenic evolution
of the Norwegian Caledonides.