Oblique strain partitioning and transpression on an inverted rift: The Castilian Branch of the Iberian Chain

Abstract

The Iberian Chain is a wide intraplate deformation zone formed by the tectonic inversion during the Pyrenean orogeny of a Permian –Mesozoic basin developed in the eastern part of the Iberian Massif. The N – S convergence between Iberia and Eurasia from the Late Cretaceous to the Lower Miocene times produced signi cant intraplate deformation. The NW –SE oriented Castilian Branch of the Iberian Chain can be considered as a “key zone ” where the proposed models for the Cenozoic tectonic evolution of the Iberian Chain can be tested. Structural style of basin inversion suggests mainly strike slip d–isplacements along previous NW –SE normal faults, developed mostly during the Mesozoic. To con rm this hypothesis, structural and basin evolution analysis, macrostructural Bouguer gravity anomaly analysis, detailed mapping and paleostress inversions have been used to prove the important role of strike slip deformation. In addition, we demonstrate that two main folding trends almost perpendicular (NE SW t–o E W an–d NW SE) w–ere simultaneously active in a wide transpressive zone. The two fold trends were generated by dierent mechanical behaviour, including buckling and bending under constrictive strain conditions. We propose that strain partitioning occurred with oblique compression and transpression during the Cenozoic.