Opposite verging chains sharing the same foreland: Kinematics and interactions through analogue models (Central Po Plain, Italy)

In this study, we investigate the potential role played by different geological factors on the development of a thrust system. In particular our goal is to analyze how pre-existing compressional structures located in the foreland of a thrust-and-fold beltmay affect the kinematics of a thrust system.Westudied such circumstances both in a natural case and through analogue models. As a natural case,we selected the Central Po Plain (Italy),where the buried external fronts of the Northern Apennines and Southern Alps are very close to each other. Starting from a regional cross-section representative of this tectonic setting, we reconstructed the post-Messinian development of the Apennines thrust fronts, which includes out-of-sequence thrusting. Then, we modeled this evolution through a set of analogue experiments to evaluate the possible relationships of the out-of-sequence thrusting with the burial of the syntectonic sediments and/or the existence of the outer fronts of an opposite verging chain in its foreland. The comparison between natural case and models highlights that the presence of opposite verging thrust fronts in the foreland of a belt limits the propagation of new thrusts favoring the out-of-sequence reactivation of inner thrusts. An analysis of the study areawith respect to adjacent tectonic settings, coupled with analogue models, revealed that syntectonic sedimentation aswell has a role in the reactivation of the inner fronts, although secondary. In the Po Plain specific case, this implies that the presence of the buried Southern Alps fronts affects the Northern Apennines kinematics, even if the two fronts did not collide yet.