[1] Three-dimensional dynamically consistent laboratory models are carried out to model the large-scale mantle circulation induced by subduction of a laterally migrating slab. A laboratory analogue of a slab - upper mantle system is set up with two linearly viscous layers of silicone putty and glucose syrup in a tank. The circulation pattern is continuously monitored and quantitatively estimated using a feature tracking image analysis technique. The effects of plate width and mantle viscosity/density on mantle circulation are systematically considered. The experiments show that rollback subduction generates a complex three-dimensional time-dependent mantle circulation pattern characterized by the presence of two distinct components: the poloidal and the toroidal circulation. The poloidal component is the answer to the viscous coupling between the slab motion and the mantle, while the toroidal one is produced by lateral slab migration. Spatial and temporal features of mantle circulation are carefully analyzed. These models show that ( 1) poloidal and toroidal mantle circulation are both active since the beginning of the subduction process, ( 2) mantle circulation is intermittent, ( 3) plate width affects the velocity and the dimension of subduction induced mantle circulation area, and ( 4) mantle flow in subduction zones cannot be correctly described by models assuming a two-dimensional steady state process. We show that the intermittent toroidal component of mantle circulation, missed in those models, plays a crucial role in modifying the geometry and the efficiency of the poloidal component.

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viscous coupling intermittent toroidal component of mantle circulation missed feature tracking image analysis twodimensional steady poloidal component dynamically consistent laboratory plate width velocity threedimensional timedependent mantle circulation pattern subduction zones

Bui, HA,Cenedese, A ,Moroni, M ,Funiciello, F ,Faccenna, C ,Piromallo, C ,.Mapping mantle flow during retreating subduction: Laboratory models analyzed by feature tracking. 111 (),16.

Bui, HA, et al."Mapping mantle flow during retreating subduction: Laboratory models analyzed by feature tracking" 111

Bui, HA,Cenedese, A ,Moroni, M ,Funiciello, F ,Faccenna, C ,Piromallo, C ,"Mapping mantle flow during retreating subduction: Laboratory models analyzed by feature tracking"