Crustal-scale balanced cross-section and restorations of the Central Pyrenean belt (Nestes-Cinca transect): Highlighting the structural control of Variscan belt and Permian-Mesozoic rift systems on mountain building

Abstract

In this paper, we combined new field geological, structural, paleo-temperature and subsurface data together with deep geophysical data to build a new 210\u202fkm-long crustal-scale balanced and sequentially restored cross-section in the Central Pyrenean belt (Nestes-Cinca transect). The present-day surficial thrust system geometry of the belt consists of bi-vergent basement-cover thrust sheets with inverted extensional basins and halokinetic structures. Its crustal geometry consists of a thrust wedge geometry of the European lithosphere between the Axial Zone imbricate system of the Iberian upper crust and the north-directed subduction of the Iberian lower crust. Along the study transect, the contractional belt corresponds to the inversion of the Mesozoic Pyrenean Rift system, which consisted in a hyper-extended relay zone of two metamorphic zones with exhumation of lithospheric mantle, the Montillet and Baronnies zones, separated by the Barousse upper crustal boudin. Surface and subsurface data show that the European and Iberian crusts include major inherited structures of the Variscan belt and Permian Rift. These old crustal features controlled the location and geometry of the Mesozoic Pyrenean Rift system. During the upper Cretaceous-lower Miocene contraction, both Paleozoic and Mesozoic inherited features controlled the thrust kinematics and the structural architecture of the Pyrenean orogen. Palinspastic restorations show that the orogenic shortening recorded in the Central Pyrenean belt reaches 127\u202fkm (39%) including the closure of the hyper-extended Pyrenean Rift system that initially archived 56\u202fkm of extension. This study emphasizes the long-term influence of Paleozoic-Mesozoic structural and thermal inheritances for the evolution of orogenic belts.