We developed a 2 D numerical model to simulate the evolution of two superposed ocean-continent-ocean subduction cycles with opposite vergence,both followed by continental collision,aiming to better understand the evol...We developed a 2 D numerical model to simulate the evolution of two superposed ocean-continent-ocean subduction cycles with opposite vergence,both followed by continental collision,aiming to better understand the evolution of the Variscan belt.Three models with different velocities of the first oceanic subduction have been implemented.Striking differences in the thermo-mechanical evolution between the first subduction,which activates in an unperturbed system,and the second subduction,characterised by an opposite vergence,have been enlighten,in particular regarding the temperature in the mantle wedge and in the interior of the slab.Pressure and temperature(P-T) conditions predicted by one cycle and two cycles models have been compared with natural P-T estimates of the Variscan metamorphism from the Alps and from the French Massif Central(FMC).The comparative analysis supports that a slow and hot subduction well reproduces the P-T conditions compatible with data from the FMC,while P-T conditions compatible with data of Variscan metamorphism from the Alps can be reproduced by either a cold or hot oceanic subduction models.Analysing the agreement of both double and single subduction models with natural P-T estimates,we observed that polycyclic models better describe the evolution of the Variscan orogeny.展开更多
基金partially supported by the MIUR-PRIN 2011 project(2010AZR98L)‘Birth and death of oceanic basins:geodynamic processes from rifting to continental collision in Mediterranean and CircumMediterranean orogens’by the SISMA-Pilot Project‘SISMA-Information System for Monitoring and Alert’(ASI contract No.Ⅰ/093/06/0)。
文摘We developed a 2 D numerical model to simulate the evolution of two superposed ocean-continent-ocean subduction cycles with opposite vergence,both followed by continental collision,aiming to better understand the evolution of the Variscan belt.Three models with different velocities of the first oceanic subduction have been implemented.Striking differences in the thermo-mechanical evolution between the first subduction,which activates in an unperturbed system,and the second subduction,characterised by an opposite vergence,have been enlighten,in particular regarding the temperature in the mantle wedge and in the interior of the slab.Pressure and temperature(P-T) conditions predicted by one cycle and two cycles models have been compared with natural P-T estimates of the Variscan metamorphism from the Alps and from the French Massif Central(FMC).The comparative analysis supports that a slow and hot subduction well reproduces the P-T conditions compatible with data from the FMC,while P-T conditions compatible with data of Variscan metamorphism from the Alps can be reproduced by either a cold or hot oceanic subduction models.Analysing the agreement of both double and single subduction models with natural P-T estimates,we observed that polycyclic models better describe the evolution of the Variscan orogeny.
