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

Abstract

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 of collision tectonics between the European and Adriatic plates. The superposition of different deformational styles highly reworked the originally complex palaeogeography of this portion of the southern Tethyan margin. Analogue modelling has been performed on thrusting mechanisms in the Abruzzi–Molise area in order to (1) reduce the number of admissible hypotheses regarding palaeogeographic setting, and (2) define thrusting mechanics. Both of these goals are crucial for hydrocarbon exploration purposes. The sandbox apparatus used to simulate the undeformed passive margin consisted of a thin compartment juxtaposed against a thick one along a linear boundary having variable geometries and mechanical stratigraphy; a rigid but mobile backstop was used to deform the stratigraphy in a Coulomb thrust wedge. Results from six experiments show that the geometric relationships between different structural units depend on the distribution of palaeogeographic domains. These domains are defined by mechanical and/or geometrical parameters, such as the orientation between the maximum compression direction and the palaeogeographic boundary, the mechanical stratigraphy and the thickness of the successions reproduced in the models. The present-day tectonic styles and Meso–Cenozoic palaeogeography of the Abruzzi–Molise area are discussed in terms of the mechanisms and structures analysed through the models.