GNGTS 2014 - Atti del 33° Convegno Nazionale

16 GNGTS 2014 S essione 1.1 faults. Such a complexity suitably results from the interplay between regional extension direction and local structural inheritances. The geomorphological analysis has allowed the detection of rectilinear scarps/slope breaks and the drainage net anomalies, which also affect the eroded surfaces formed in the Prata Sannita basin fill. Such indicators point to the occurrence of a network of several hundreds to few km-long fault strands with NW-SE, E-W and N-S trends. Fault scarps with N-S trend are dominating in the Colle Sponeta area. These include the N-S trending, up to about 8 m high and about 1 km long, E-facing Colle Sponeta fault scarp, shown in Figs. 2a and 2b. Preliminary data on the distribution of CO 2 , He and CO 2 flux in the surveyed Colle Sponeta area are synthesised in Table 1 and Fig. 3. Table 1 shows the main statistics of the analysed gas species. Such data highlight the following considerations: • CO 2 mean value (6.81%) is higher, but comparable to the mean value calculated for the surveyed volcanic areas of the central and southern Italy (4.77%), and to the mean value calculated for theLatera caldera in northern Latium (9.54%). • He mean value (7.07 ppm) is not comparable to the mean value calculated for the Italian volcanic areas, because the latter is biased by a very high maximum value (10325 ppm). However, the geometric mean values are comparable (6.22 and 5.67 ppm, respectively); • CO 2 flux mean value (103.60 g m -2 d -1 ) is lower than that calculated for the volcanic areas, however it is twice the typical soil values (about 40 g m -2 d -1 , Beaubien et al. , 2014). Fig. 3 – Distribution maps of CO 2 (a), He (b) and CO 2 flux (c) in the Colle Sponeta area. All gases highlight a series of gas-vents aligned along the Colle Sponeta fault scarp.