2D numerical models of passive margin reactivation

Subduction is a key driving mechanism in Plate Tectonics, but how it initiates is still poorly understood.

Subduction initiation is thought to be a complex and evolving tectonic process. It consists of stages of lithospheric contractional deformation that may reactivate inherited structures, potentially localizing deformation in a proto-plate boundary and leading to subduction of one of the plates. One way subduction initiation may occur is through the reactivation of a passive margin.

The processes that generate a self-sustained subduction zone are still debated and are thought to be dependent on various factors, such as the presence of a weak zone (e.g., a serpentinized layer), a pre-existing stress/strain field, the structure of the rifted margin and the age of the subducting oceanic plate.

Using high-resolution 2D geodynamic numerical models carried out with the code LaMEM, this work investigates the mechanisms that may control the reactivation of rifted margins. In particular, by testing different parameters (e.g., length of the passive margin, presence of a serpentinized layer), different deformation regimes (e.g., strain-rates) and the thermomechanical state of the system (e.g., temperature profiles and rheology) that may lead to subduction initiation in these locations.

Our preliminary results show that serpentinized layers facilitate the reactivation of inherited rift structures by localizing deformation. The results also show that the length of the passive margin might influence the location of the subduction nucleation.