Architecture and deformation mechanisms within a carbonate-hosted fault zone (Fucino basin)

The Central Apennine is one of the most seismically active regions in the Mediterranean area and is affected by moderate to large shallow earthquakes that enucleate in and propagate through carbonate rocks. In this work we present a detailed fieldwork and microstructural analysis to define the architecture and deformation mechanisms of an exhumed fault zone in carbonates, the Tre Monti fault, at the northern boundary of the Fucino Basin. Fault rocks assemblage show differences in deformation mechanisms between the main and external fault planes, and subsidiary fault planes developed within the damage zone. We infer that this variety of fault rocks represents different deformation processes acting during different stages of fault development and fluid circulation. The multidisciplinary but field-based study of fault surfaces and fault rocks is fundamental to reveal the geological record of past earthquake and seismic cycles and is strongly complementary to the seismological-based one.