Evolution of rift-related cover-basement decoupling revealed by brecciation processes in the eastern Pyrenees

Breccias associated with tectonic, fluid and sedimentary evolution of rifted margins can provide information on a variety processes reflecting the modes extension. In this paper, we analyse numerous breccias exposed in Agly Massif that was part European side Cretaceous rift now inverted eastern Pyrenees. Using combination petrologic sedimentologic analyses, field-based structural study, multivariate analysis clast shape diversity, binding lithology size, breccia fabrics, distinguish 5 types depositional, salt-related processes. The integration these tectonic history Pyrenees confirms attribution to rifting. We emphasize major role played by evaporitic Triassic particularly during first stages rifting as decoupling level at basement/cover interface. Salt tectonics shearing assisted circulation fluids are reflected hydrofracturing base Mesozoic cover. As weak mechanical layer is later extracted extension increases, brittle detachment system developed along cover-basement interface exhume deep crust mantle. relationships between brecciation argue for mixed mode ductile deformation formation hyper-extended domain.