Linking structures with the genesis and activity of mud volcanoes: examples from Emilia and Marche (Northern Apennines, Italy)

Abstract

Mud volcanism is known to be strictly linked to tectonic structures, since they have the ability to trap hydrocarbon and other fluids, and eventually induce them to migrate from a deep reservoir (e.g. sited into an anticline core, where large overpressures may be generated), to the surface. A central theme is how fluids can migrate upward, and which is the role in this process of near structures (i.e. structures directly controlling the mud volcano system) and far structures (i.e. faults located far away from the mud volcano system). In this study, we investigate the role of both types of structures in the genesis and evolution of mud volcanoes. In particular, we investigate six mud volcano case studies from the Emilia-Romagna and Marche Pede–Apennine margin, in Italy, through integration of fieldwork, interpretation of available seismic reflection profiles and aerial photos. The results of these analyses support an intimate link of the investigated mud volcanoes with anticline structures. We discuss two different fluid migration settings, particularly (i) mud volcanoes emplaced on outcropping anticlines, and (ii) mud volcanoes located on top of buried structures, discerning when fluids are likely to exploit anticline-related fracture sets, or secondary structures and porosity. Finally, we speculate on how far structures, via the seismic triggering, may play a role in the occurrence of historical eruption of some of the investigated mud volcanoes.