THE ROLE OF RIFT-INHERITED HYPEREXTENSION FOR THE FORMATION OF COLLISIONAL OROGENS: INSIGHTS FROM THE ALPS (WESTERN EUROPE)
However, the resulting pre-orogenic template still awaits to be integrated in models focusing on mountain belts formation. In this presentation, we explore how the complexity of rift-inheritance, and in particular hyperextension, may control the evolution and final architecture of the collisional stage of orogenic systems.
The Alpine belt in Western Europe constitutes one of best-studied orogenic system worldwide preserving the relics of the Alpine Tethys. Based on surface and geophysical data, we suggest that the architecture and evolution of Alpine orogeny are strongly controlled by rift inheritance. We propose that the architecture of the Alpine belt results from the orogenic collage of distinct domains of the former rifted margins. The intensity of the reactivation and inversion of these former domains within the orogen is a direct consequence of their pre-orogenic architecture and crustal thickness. The highly deformed internal part samples the remnants of hyperthinned domains whereas the weakly deformed external parts preserve domains that where only weakly affected by the rifting. Consequently, the evolution of the Alpine orogen strongly depends on the architecture of the former rifted margins. The transition from subduction to collisional stage occurs when the necking zones and thick continental crust become involved in subduction, acting as buttresses.
Eventually, the adoption of a more “realistic” pre-orogenic template may lead to a better understanding of mountain belt formation processes but may also provide new insights for plate tectonic reconstructions.