Basement-cover thermochronological coupling reveals lithospheric-scale geodynamics in the Western Mediterranean realm (South-East France)

The thermo-tectonic evolution of the Western Mediterranean realm reflects the superimposition of several orogenic phases inclusing the Pyrenean convergence, the Alpine collision and subsequent back-arc extension related to the opening of the Liguro-Provençal Basin. However, the long-wavelength geodynamic forcing driving this evolution remains debated. Most reconstructions rely either on basement-derived thermochronology or on basin-scale stratigraphic records, leading to segmented and sometimes conflicting interpretations. Here, we present a coupled thermochronological approach integrating crystalline basement massifs and their sedimentary cover to reconstruct the continuous geodynamic evolution of southeastern France within the Western Mediterranean realm from the Cretaceous to the Oligo-Miocene. We combine apatite and zircon fission-track and (U–Th)/He data from the Maures–Tanneron and Pelvoux crystalline massifs with new oxy-hydroxide (U–Th)/He constraints from karst-hosted bauxites and subalpine sedimentary systems of the Vocontian Basin. These datasets are jointly interpreted to derive regionally consistent time–temperature paths.

Results reveal a coherent lithospheric-scale thermal signal characterized by (i) mid-Cretaceous oxide crystallization related to Durancian Isthmus uplift, coeval with heating of the crystalline massifs, (ii) Late Cretaceous to Paleogene heating followed by cooling of bauxites driven by flexural and tectonic burial during Pyrenean convergence, synchronous with exhumation of adjacent crystalline massifs, and (iii) Oligo-Miocene heating and cooling associated with Liguro-Provençal back-arc rifting. These thermal trends are independently supported by U-Pb calcite ages documenting brittle deformation and fluid circulation within subalpine and Vocontian basins.

Basement and cover record synchronous thermal responses, while U-Pb calcite ages constrain the brittle response of sedimentary basins to the same lithospheric-scale deformation, indicating that sedimentary basins acted as passive recorders of lithospheric-scale forcing rather than isolated depocenters. This coupled approach demonstrates that long-wavelength geodynamic forcing controlled both exhumation of crystalline massifs and subsidence of adjacent basins, providing a unified thermo-tectonic framework for the Western Mediterranean realm.