Subduction And Plate Motion In Laboratory. European Geosciences Union.

We have performed 3-D laboratory experiments to test the influence of factors controlling plate and trench motion of a subducting plate. The systematic study has been carried out widely changing geometrical and rheological parameters of the system and testing the relative influence on the kinematics of subduction. A total number of 60 different experiments have been performed using variable combinations of thickness, viscosities, densities of the plate and mantle. We have scaled down our experiments to natural gravity field using silicone putty and honey to simulate the viscous behavior of slab and mantle, respectively. Our models can be divided in two classes typified by a different style of subduction: a "retreating" style of subduction characterized by the backward motion of the trench and the slow advancing motion of the plate, and an "advancing" style, where trench is stationary or advance towards the upper plate and the plate move in faster way. The latter condition is found to be more difficult to be obtained. In general terms, the two behaviors depend upon the distribution of the forces active into the system. If driving forces are much more elevated than resisting ones the system is more prone to retreat. The result we obtained in terms of velocity of subduction, in addition, is original with respect to previous works. We found a velocity of subduction which is always much greater than the one calculated by using simple equations. Hence we pointed out that a precise evaluation of subduction velocity could not be done assuming a constant radius of curvature.