Influence of palaeogeography on thrust system geometries: an analogue modelling approach for the Abruzzi-Molise (Italy) case history

The Abruzzi-Molise sector in the Central Apennines is a part of a fold and thrust belt that has been deforming since the Late Cretaceous as a result o f collision tectonics between the European and Adriatic plates. The superpo sition of different deformational styles highly reworked the originally com plex palaeogeography of this portion of the southern Tethyan margin. Analog ue modelling has been performed on thrusting mechanisms in the Abruzzi-Moli se area in order to (1) reduce the number of admissible hypotheses regardin g palaeogeographic setting, and (2) define thrusting mechanics. Both of the se goals are crucial for hydrocarbon exploration purposes. The sandbox appa ratus used to simulate the undeformed passive margin consisted of a thin co mpartment juxtaposed against a thick one along a linear boundary having var iable geometries and mechanical stratigraphy; a rigid but mobile backstop w as used to deform the stratigraphy in a Coulomb thrust wedge. Results from six experiments show that the geometric relationships between different str uctural units depend on the distribution of palaeogeographic domains. These domains are defined by mechanical and/or geometrical parameters, such as t he orientation between the maximum compression direction and the palaeogeog raphic boundary, the mechanical stratigraphy and the thickness of the succe ssions reproduced in the models. The present-day tectonic styles and Meso-C enozoic palaeogeography of the Abruzzi-Molise area are discussed in terms o f the mechanisms and structures analysed through the models. (C) 1998 Elsev ier Science B.V. All rights reserved.