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.

本研究聚焦福利尼奥山脉北部的侏罗纪古地理与构造演化。一项1:10000比例尺的地质调查揭示了侏罗纪伸展断裂作用对沉积环境的影响。早在早侏罗世，马西乔灰岩（Calcare Massiccio）碳酸盐岩台地内就因断裂作用出现了持续的水深差异，但受断裂围限的构造高地仅在台地解体后才得以形成。主要抬升构造——萨索迪帕莱-蓬特圣卢西亚（Sasso di Pale – Ponte Santa Lucia）可被解释为地垒状构造，受反向东东南-西西北向断裂围限，其表面平缓倾斜，遭受滑动作用与边缘侵蚀。该断裂在早侏罗世期间的总断距已超过500米，形成的陡峭断崖仅部分被沉积物掩埋。中侏罗世至晚侏罗世期间，这些断裂断崖高出海底150~200米，长期暴露导致了减压相关破裂与块体滑脱作用。