Gravity modelling of central Apennines deep structures along CROP11 seismic profile.

Gravity method represents an important tool for the definition of the deep structural style of a mountain belt. Moreover, the possibility to use independent geophysical data sets, such as seismic reflection data and gravity data results particularly appropriate for the reconstruction of the deeper portion of the crust.In the present work 2D and 3D gravity data inversion was used to study deep crust. The interpretation of gravity data are based on the deep-sourced gravity anomalies map obtained by means of the stripping procedure starting from the Bouguer anomalies. The reduction density for Bouguer anomaly correction was 2.67 g/cm3. The stripping has been done on the base of accurate 3D lithological model of the surficial Apennine units (BERNABINI et alii, 1996a; BERNABINI et alii, 2002a; 2002b). As the stripped gravity data concerns essentially the deep crust, the modelling presented in this work takes into account only deep-sourced gravity anomalies. The gravity modelling are constrained by DSS data (NICOLICH, 1981; SCARASCIA et al., 1994; BIELLA et al., 1997) and by deep reflection seismic data obtained along the CROP 11 line (BILLI et al., 2001; BIGI et al., 2003), that crosses the Apennine from Marina di Tarquinia (W) to Vasto (E).The regional gravity anomaly trend of Central Italy is interpreted and its role as an independent constraint for the geological interpretation of the CROP 11 seismic line is also discussed. Gravity data used in this work consist in Bouguer anomaly values provided by National Geological Service and obtained by a 3 km sampling of the database of all the Italian gravimetric stations. (*) This work has been carried out within the CROP 11 project (prof. M. Parotto co-ordinator)