A gas geochemical prospection has been carried out in a tectonically active area located in the Southern Apenninic Belt (Italy) with the purpose to investigate the origin of local gaseous emissions. On the basis of helium isotopic
ratios, a high contribution of deep-marked fluids has been recognised. Local field evidences of gases flow rate do not seem consistent with only a mantle provenance of the fluids. It seems likely that the gases source has to be located at shallower depth than the crust-mantle transition