Reconstruction of pre-thrusting basin architecture: the contribution of the 3-D modeling approach

The three-dimensional (3D) reconstruction of complex geological settings and of original, pre-thrusting basin geometry is one of the challenges for modern structural geology. It has indeed a critical role in many industrial applications, such as in the hydrocarbon exploration. 3D modelling techniques provide tools for an enhanced understanding of the evolution of structurally complex domains, and for the validation of paleogeographic reconstructions. In combination with classical 2D restoration techniques, 3D modelling allows to better constrain the otherwise not always clear mean direction of tectonic transport, the kinematics and the internal consistency of interpreted geometry of investigated structures. By back-stripping the deformation (tectonics and compaction), it is possible to reconstruct a set of pre-deformation templates depicting the tectonic evolution through time. These computations may also be used to provide semi-quantitative estimates of tectonically relevant parameters. By using commercial specific softwares to produce balanced cross-sections and inferred 3D reconstructions (2Dmove, Gocad), we modelled a portion of the Umbria- Marche fold-and-thrust belt, in order to infer the pre-thrusting geometry of the Mesozoic-Cenozoic extensional basins and test the applicability of existing computer tools in areas that have experienced the effects of positive tectonic inversion.