GIS and 3D geological reconstruction of the Zuccone gravitational deformation: Val Taleggio (Southern Alps)

A geological map can be considered as one of the best tool to display the geometrical relationships among geological bodies. Moreover their extent can be appreciated in three dimensions, applying geometrical techniques (Ramsay and Huber, 1987; Powell, 1992, de Kemp, 2000), when topographic and structural data are also available. The aim of this work is to show how geological cartographic data stored in a Geographic Information System (GIS) can be used for 3D modeling of complex geological bodies, using a special procedure (Sterlacchini and Zanchi, 2001; Zanchi et al., 2002; 2003). 3D reconstruction has been performed in gOcad, a software based on the discrete smooth interpolator (Mallet, 1997), which makes possible the creation of 3D surfaces, volumes and grids starting from simple features, as points and lines. These techniques have been applied to the reconstruction of the Corno Zuccone deep seated slope gravitational deformation (Crosta et al., 1999, Zanchi et al., 2002, 2003) developed within the sedimentary cover of the Southern Alps, Italy (fig. 1). The DSSGD occurs within a complex thrust stack (Schonborn, 1992; AAVV, 2000), later affected by strike-slip and normal faults. These structures have been modelled basing on detailed structural, morpho-structural and geological data (1:5,000-1:2,000). All the needed data were firstly stored and integrated within a GIS, to be later generalized and imported into gOcad. The 3D model has been reconstructed through several steps which will be illustrated in the next sections.