Lithological control and structural inheritance on faults growth in multilayer foreland sequences

Abstract

Foreland sectors and foredeep-forebulge systems are affected, as the orogenic wedge migrates, by successive stages of stress states and tectonic deformation, resulting in the development of complex fault networks, even if characterized by limited deformation. The role played by structural inheritance and changes in stress field through time, in influencing the successive re-activations of fault segments, is still a topic to be thoroughly investigated. In this work, thanks to an extensive database made available by courtesy of Energean, we were able to investigate a foreland sector at the margin of the southern Apennines. By means of thickness analysis of the Neogene foredeep sequence and of displacement analysis along the fault network, we documented a shift from forebulge-related extension, in Early Pliocene, to a new tectonic phase, since Middle Pliocene, related to a strike slip stress field, possibly related to the activity of the Tremiti Fault Zone. We also characterized the geometry and connectivity of the cover-restricted faults, developing above propagating normal faults and observed a clear correlation between fault propagation tendency and lithological/mechanical layering within the cover units.