New constraints for indentation mechanisms in arcuate belts from the Jura Mountains, France

The mechanism of indentation in arcuate belts is discussed using the Jura Mountains as an example. Using fault-inversion analysis from numerous sites, the Miocene-Pliocene stress pattern is reconstructed. Two superimposed compressional stress fields have been recognized. Considering the theoretical distribution of compression in front of a rigid indenter, we interpret the complex stress pattern in the Jura Mountains as a result of a major change in the mechanism of indentation of the Jura by its hinterland. Initially, the indenter was narrower and limited in the southwest by the Vuache transfer fault. With time, it expanded to the southwest and included the entire Molasse basin. This evolution highlights the importance of decoupling along faults, which here controlled the indenter shape.