Extensional and compressional regimes exist at the same time in adjacent parts of the Northern Apennines (Italy), and the former regime succeeded the latter at the same place as the thrust mountain front moved eastward since Miocene times. Numerous extensional basins have developed west of the present mountain divide. The westernmost ones formed over attenuated continental crust since Late Miocene and have been subjected to several subsidence and uplift events, with rates of subsidence generally faster than rates of sedimentation. They contain continental deposits overlain by gypsum-bearing Upper Miocene marine sequences and siliciclastic, marine Pliocene deposits. These basins were affected by shallow magmatism and are still experiencing high geothermal gradient and late to post-magmatic activities, such as in the renowned thermal region of Larderello. To the east, closer to the present mountain divide, the extensional basins formed later, from Pliocene to Quaternary, contain continental (fluvial and lacustrine) deposits and have not experienced near-surface magmatic activities.
   The sedimentary fill architecture of the Apennine extensional basins is similar to that of other European, American and African extensional or transtensional systems. For instance, a common characteristic is the prevalence of large alluvial fan deposits at the hanging-wall shoulder of half-grabens, coarser, smaller, alluvial fans at the footwall shoulder, and some fluvial deposits introduced longitudinally. Unlike the African rifts though, the sedimentary facies distribution of extensional basins which developed in active orogenic zones such as in the Apennines, may be strongly affected by uplifting, steep mountain slopes and can have large, thick, coarse alluvial fans also on the footwall side of the half-grabens.

[Home] [Books] [Papers] [Reports] [Conference Papers] [Supervised Theses] [Others]