Multidisciplinary study of non-volcanic degassing vent field in the Solopaca area (southern Apennines)

In the southern Apennines, evidence of non-volcanic degassing is widespread reported. Geochemical surveys indicate that the gases are mainly formed by CO2. In particular, degassing vents are focused along the SW margin of the Matese Mts. The main vents are located at north in Ciorlano, Pratella and Ailano areas, and at south in the Telese-Solopaca sector. The CO2 flux reaches high values in these areas, with the Ciorlano vent being one of the world’s highest non-volcanic CO2 fluxes. Geophysical investigations on these non-volcanic vents mark a close relation between degassing and tectonics, indicating that the fluids migrate upward along preferred pathways corresponding to damage and cataclastic zones of major faults. The SW margin of the Matese Mts is delimited by the Southern Matese Fault (SMF) system characterized by different segments with dominant normal kinematics that lowered the SW area (Alife and Telese plains). Historical seismicity occurs along the southern margin of Matese Mts, including the ancient earthquake that occurred in 346 CE (M 7.0) that some authors indicate as resulting from the reactivation of the entire SMF system. Despite the historical earthquake occurrences, instrumental seismic activity is presently negligible. The SMF system seems to continue southward, bounding the hills northward of Solopaca town; however, geological evidence is a few, and in general, the area is poorly studied. Hence, we analyzed the area northward of the Solopaca town where a CO2 degassing vent field occurs, never studied before. We performed stratigraphic, structural, geophysical and geochemical investigations in order to reconstruct the tectonic architecture of the area and shed light on the possible southward prosecution of the SMF system.