Thermal and exhumation histories of the northern subalpine chains (Bauges and Bornes—France): Evidence from forward thermal modeling coupling clay mineral diagenesis, organic maturity and carbonate clumped isotope (Δ47) data

Assessing the thermal evolution of sedimentary basinsover time is a major aspect of modern integrated basin analysis. While the behavior of clay mineralsand organic matter with increasing burial is well documented in different geological and thermal settings, these methods are often limited by the temperature ranges over which they can be precisely applied and by the available material. Here, we explore the emergent Δ_(47) clumped isotope geospeedometry (based on the diffusional redistribution of carbon and oxygen isotopes in the carbonate lattice at elevated temperatures) to refine time‐temperature paths of carbonate rocksduring their burial evolution. This study provides a reconstruction of the thermal and exhumation history of the Upper Cretaceous thrust belt series in the western subalpine massifs (Bauges and Bornes, French Alps) by a new approach combining for the first time available data from three independent geothermometers. The investigated area presents two zones affected by contrasting thermal histories. The most external zone has undergone a relatively mild thermal history (T 160–180°C) that induced widespread clay mineraldiagenetic transformations (progressive illitizationfrom R0 to R1 and R3 illite‐smectite mixed‐layers), organic matter maturation (oil window) and Δ_(47) thermal resetting with apparent equilibrium temperatures above 160°C. The three employed geothermal indicators conjointly reveal that the investigated Upper Cretaceous rocks have suffered a wide range of burial temperatures since their deposition, with a thermal maximum locally up to 160–180°C. High temperatures are associated with the tectonic emplacement of up to 4 km of prealpine nappesin the northern part of the studied area. Finally, a forward thermal modeling using Δ_(47), vitrinitereflectance and clay mineraldata, is attempted to precisely refine the burial and exhumation histories of this area.