Episodic slab rollback fosters exhumation of HP-UHP rocks

Laurent Husson (1) , Jean-Pierre Brun (1) , Philippe Yamato (1) , Claudio Faccenna (2)

1 GR - Géosciences Rennes
2 Dipartimento di Scienze Geologiche [Roma TRE]

The burial-exhumation cycle of crustal material in subduction zones can either be driven by the buoyancy of the material, by the surrounding flow, or by both. High pressure and ultrahigh pressure rocks are chiefly exhumed where subduction zones display transient behaviours, which lead to contrasted flow regimes in the subduction mantle wedge. Subduction zones with stationary trenches (mode I) favour the burial of rock units, whereas slab rollback (mode II) moderately induces an upward flow that contributes to the exhumation, a regime that is reinforced when slab dip decreases (mode III). Episodic regimes of subduction that involve different lithospheric units successively activate all three modes and thus greatly favour the exhumation of rock units from mantle depth to the surface without need for fast and sustained erosion.

Mots clés: High strain deformation zones; Continental margins: convergent; Dynamics of lithosphere and mantle; Subduction zone processes

Domaines: Tectonique

Laurent Husson, Jean-Pierre Brun, Philippe Yamato, Claudio Faccenna. Episodic slab rollback fosters exhumation of HP-UHP rocks. Geophysical Journal International, 2009, 179 (3), pp.1292-1300. ⟨10.1111/j.1365-246X.2009.04372.x⟩. ⟨insu-00553853⟩