Mesozoic structural inheritance in the Cenozoic evolution of the central Catalan Coastal Ranges (western Mediterranean): Structural and magnetotelluric analysis in the Gaià-Montmell High

Abstract

The control exerted by the Mesozoic basin configuration on the Cenozoic tectonic evolution of the Catalan Coastal Ranges has been frequently recognized as a key factor to explain its present-day structure. However, details of this structural inheritance and its evolution through geological time is still under discussion. In this work we present two structural cross-sections based on fieldwork, well and magnetotelluric data in order to illustrate the structural styles and tectonic evolution of the Gaià-Montmell High. Here, the Montmell Fault not only constitutes the SW segment of one of the major Neogene faults in the Catalan Coastal Ranges (the Montmell-Vallès Fault System), but also the NW limit of a Late Jurassic-Early Cretaceous extensional basin(the Montmell-Garraf Basin), facts that denote a major role of this fault in the tectonic evolution of the area. The present-day structure of the Gaià-Montmell High resulted, therefore, from two successive episodes of inversion during the Cenozoic. The first one reactivated the Montmell Fault as compressional during the Paleogene. As a result, and among other inversion-related structures, the Gaià-El Camp Thrust developed sa major NW-directed basement footwall shortcut. Later on, the previously formed compressional structure during the Paleogene became reactivated as extensional during the Neogene. During this phase, the reactivation of the Montmell Fault looks limited and, hence, the extension is transmitted to the Baix Penedès Fault. The reactivation of the Gaià-El Camp Thrust is also manifest in the development of an array of extensional faults in the backlimb of the Carme-Cabra Anticline that corresponds to the NE-end of El Camp Fault. This episode of negative inversion developed accommodation zones between the four major faults present in the area ( Vallès-Penedès, Montmell, El Camp and Baix Penedès faults) that are characterized by the presence of relay ramps with breaching faults.