Geological and soil-gas investigations for tectonic prospecting: Preliminary results over the Val Roveto Fault (central Italy)

In the North sector of the Roveto Valley (Central Apennines) a detailed geological-structural survey and a soil-gas prospecting have been carried out in order to investigate the existence of structural discontinuities. In the area three different discontinuity systems, Marsica Fault, a compressive element trending NW-SE and two transversal antiapenninic elements, have been recognized. Soil gas results show the pervasive character of the Rn and He high values. Both highest anomalies of He and Rn are N45 degree W oriented and well fitted with the Val Roveto Fault. Minor anomalies are congruent with local elements observed by geological investigation. The high values of He and Rn, considering the geological environment of the area (no volcanics or uraniferous deposits), lead to the inference that a vertical and rapid migration of endogenetic gases must occur and that, therefore, a great and deep fracture system should exist. Therefore the Val Roveto Fault, as also supported by previous geophysical data, may be considered as the surface expression of such deep fracture network.