The Jurassic structure of the northern sector of Foligno mountains (Central Italy)

This study examines the Jurassic palaeogeography and tectonic evolution of the northern Foligno mountains. A 1:10,000-scale geological survey highlights the impact of Jurassic extensional faulting on depositional environments. Persistent bathymetric differences due to faulting existed as early as the Early Jurassic within the Calcare Massiccio carbonate platform, but fault-bounded structural highs formed only after the platform fragmentation. The main raised structure (Sasso di Pale – Ponte Santa Lucia) can be interpreted as a horst-like feature, bordered by antithetic ESE-WNW faults, with a gently tilted surface affected by sliding processes and edge erosion. The faults reached a total throw of over 500 m already during the Early Jurassic, forming steep escarpments only in part buried by sedimentation. During the Middle and Late Jurassic, these fault scarps protruded 150–200 m above the sea floor, and their prolonged exposure resulted in decompression-related fracturing and block detachments.