U-Pb carbonate dating reveals long-lived activity of proximal margin extensional faults during the Alpine Tethys rifting

Syn-rift extensional faults play a significant role during the early stage of rifting. Constraining the age of faulting, and how and when deformation shifts from the proximal to the distal margin areas, is crucial for the reconstruction of the rifting process. Previous assessments of the structural and temporal evolution of rift-related faults of the Adria proximal margin have primarily relied on indirect biostratigraphic evidence. Additionally, the majority of rift-related faults underwent tectonic inversion during the Alpine orogeny. In this study, in-situ U-Pb geochronology was applied on syn-kinematic calcites to unravel the activity of the Amora Fault, a remarkable example of a Jurassic growth fault unaffected by the Alpine orogeny. The obtained ages, spanning from Hettangian to Callovian, extend the AF activity beyond the previously established Early Jurassic time. This chrono-structural model has significant implications on the role of major extensional faults in focusing deformation throughout the rift system's evolution.