The Monviso ophiolitic massif (Western Alps), a section through a serpentinite subduction channel.

Description

The exhumation of subducted lithosphere requires a mechanically weak zone at the interface between the subduction plane and the rigid overlying mantle peridotites with a viscosity greater than 10 20 Pa.s. At shallow depths (< 40-50 km) blueschists are exhumed in accretionary wedge along the interface between the subducting plate and the overriding plate (Platt, 1993). At greater depth, serpentinites plays the role of mechanically weak layer in cool continental subduction and act as the lubricant and produce a return flow for the exhumation of eclogitic rocks. The close association of serpentinites and eclogites in the Monviso massif (Western Alps) allow to discuss the concept of subduction serpentinite channel. We propose that the Monviso ophiolitic massif corresponds to a section of a 50 km long serpentinite channel in where eclogitic blocks were exhumed between 60 and 45 Ma and ended whEuropean continental margin was involved in the southeast dipping subduction zone.

Additional details