In collision belts, the first-order role of the mantle in localizing deformation has remained elusive, as the resolution of geophysical imaging remains too low to constrain crustal geometry. To address this issue, we geologically interpret a recent high-resolution shear-wave velocity model from ambient-noise tomography of Western Alps. We show that the lower crustal Alpine geometry is highly variable at depth, evolving from a preserved European crustal slab in the South to a smooth crustal root in the North. Moho morphology is controlled by numerous pre-existing major faults reactivated during the Alpine orogeny. Two mantle indenters located above the subducted European plate at different depths appear to control the locus of active deformation. The rigid nature of Adria mantle explains the localization of brittle deformation that is transferred towards the upper crust. The strain-field partitioning results in a combination of strike-slip with either shortening or extension controlled by the anticlockwise rotation of Adria.

Constraining the relative roles of erosion and tectonics in the evolution of mountain belts is a challenging scientific goal. In this review article on the Western Alps, we show how it becomes possible to “bridge the gap” between the long–term (>Ma) orogenic evolution controlled by tectonics and exhumation processes and the recent geomorphological evolution that is accessible on an annual–decadal basis. Advances in mineral dating that have grown in relation to deformation in the ductile and brittle crustal fields have allowed us to constrain the evolution of deformation through time and depth. A drastic change from early collision, dominated by rapid underthrusting of the European plate, to a more stagnant syn–collisional tectonic context is documented since about 26–20 Ma by syn–kinematic phengites and vein–hosted monazites along the Alpine arc. The overall dextral kinematic context is accompanied by local extensional domains in the Simplon and High Durance Valley. Activation of the Simplon ductile fault is documented from 20 Ma, whereas the High Durance extensional system commenced after 10 Ma. The application of cosmogenic nuclide dating of incised river gorges demonstrates that the erosion pattern of the Western Alps follows a different evolution within the valleys dominated by upstream glacial erosion than in peripheral watersheds devoid of glaciers. The very low peripheral incision is found to be similar to the vertical GPS signal, suggesting equilibrium of tectonic uplift and incision, whereas the glacial–dominated valleys exhibit significantly increased and transient river incision during interglacials and a constant ongoing tectonic regime.

The Vocontian Basin in southeastern France records a long-lived history of subsidence and polyphase deformation at the junction of Alpine and Pyrenean orogenic systems. This study aims to reconstruct the tectonic, burial and thermal evolution of this basin, based on new U–Pb dating of calcite from veins and faults combined with new RSCM (Raman Spectroscopy of Carbonaceous Material) thermometry and stratigraphy-based burial models. Three main generations of calcite are identified: (1) the Late Cretaceous to Paleocene period related to the Pyrenean-Provençal convergence (∼ 84–50 Ma); (2) the Oligocene period linked to the extension of the West European Rift (∼ 30–24 Ma); and (3) the Miocene period, ascribed to strike-slip and compression associated with the Alpine collision (∼ 12–7 Ma). No older ages related to the Jurassic and Early Cretaceous rifting phase are obtained, despite targeted sampling near normal faults, suggesting highly localized syn-rift fluid circulation or dissolution of early calcite mineralization during subsequent tectonic events. RSCM data highlight a pronounced east–west thermal gradient. Peak temperatures are below 100 °C in the west and exceed 250 °C in the eastern basin, reflecting greater crustal thinning and salt diapirism in the eastern Vocontian Basin with the overlapping Jurassic and Cretaceous rifting phases. These results emphasize the significant impact of the West European Rift in south-eastern France. They further highlight the potential mismatch between large-scale tectonic processes and the tectonic history inferred from calcite U–Pb dating, which is sensitive to the presence of fluids and the physical conditions required for their preservation.

The Vocontian Basin in southeastern France records a long-lived history of subsidence and polyphase deformation at the junction of Alpine and Pyrenean orogenic systems. This study aims to reconstructed the geodynamical evolution of this basin, based on new U–Pb dating of calcite from veins and faults combined with RSCM thermometry and stratigraphy-based burial models. Three main generations of calcites are dated: (1) Late Cretaceous to Paleocene dates related to Pyrenean-Provençal convergence (~84–50 Ma); (2) Oligocene dates linked to the West European Rift extension (~30–24 Ma); and (3) Miocene dates ascribed to strike-slip and compression associated with Alpine collision (~12–7 Ma). No older ages related to the Jurassic and Early Cretaceous rifting phases are obtained suggesting limited syn-rift fluid circulation or subsequent dissolution of early calcite mineralization. RSCM data highlight a pronounced E–W thermal gradient, with peak temperatures exceeding 250 °C in the eastern basin, consistent with crustal thinning and/or salt diapirism. These results emphasize the large-scale impact of the opening of the West European Rift in SE France and underscore the possible mismatch between the large-scale tectonics and the tectonic history inferred from calcite U–Pb dating, which is sensible to presence of fluids and the physical conditions for their preservations.

Recent ambient noise Vs tomography data at the scale of the Western Alps (Nouibat et al., 2022) highlight the deep structure of the chain. In the European foreland, the seismological model shows a crust of normal thickness, with slow velocities (