Jaime Almeida , Nicolas Riel, Filipe Medeiros Rosas, João Duarte, Boris J.P. Kaus 

Subduction zones have recurrently formed on Earth. Previous studies have, however, suggested that they are unlikely to start in the interior of a pristine ocean. Instead, they seem to be more likely to form from another pre-existing subduction zone. One widely cited conceptual model to start new subduction zones is polarity reversal, resulting from the shutdown of a pre-existent subduction zone due to the arrival of a buoyant block at the trench. However, the dynamic conditions by which this process occurs remain elusive. Here, we present 3D numerical models of subduction zone initiation by polarity reversal resulting from the arrival of an oceanic plateau at the trench. Our results show that this process is more likely to occur for old subducting plates and narrow plateaus, and that new subduction zones can form from previous ones in a self-replicating manner, without requiring any other external tectonic forcing.