A thermochronological transect across the Trento platform: constraints for the evolution of the European Eastern Southern Alps.

Abstract

Late Oligocene and Miocene east-west decoupling of the Alpine retro-wedge evolution along the Giudicarie fault system and the associated late-stage shortening within the eastern Southern Alps (ESA) are key features of the Neoalpine, post-collisional Adria-Europe convergence. A new thermochronological N-S transect across the Trento platform in the western ESA suggests a ~ 25 Ma onset of exhumation in the Neoalpine fold-and-thrust belt. This requires a longer lasting transfer of shortening from the Eastern Alps, north of the Periadriatic fault system, into the evolving ESA, rather than a single and distinct Middle Miocene shift to a coupled state. Still, the highest exhumation rates are observed between 17 and 10 Ma, linking rapid ESA exhumation to the termination of folding within the Sub-Penninic interior of the Tauern Window. Prior to the Neoalpine evolution, the oblique Paleogene collision of northeast-Adria and Europe entailed Dinaric top-southwest thrusting on the Adriatic microplate. An Eocene antiformal basement structure and an assumed blind fault in the northwestern ESA, revealed by new thermochronological data, mark the northwestern extend of the Dinaric fold-and-thrust belt. Apart from Dinaric and Neoalpine exhumation related cooling, Adria was affected by Eocene to Oligocene subduction-related magmatism, Late Triassic-Early Jurassic extension, middle Triassic strike-slip tectonics, and Permian extension. Each event, as well as the Permian to Cretaceous burial, resulted in the thermal perturbation of the Adriatic crust and its sedimentary cover. Statistical analyses of apatite fission-track single-grain ages emphasize the imprint of the post-Permian thermal evolution, as detrital ages and magmatic formation ages are overprinted or obliterated throughout the study area. Jurassic and Cretaceous apatite fission-track data are attributed to a widespread exhumed partial annealing zone.

Supplementary information: The online version contains supplementary material available at 10.1186/s00015-025-00491-w.