La tectónica de inversión en una región intraplaca: la Cordillera Ibérica

La Cordillera Ibérica es una cadena intraplaca formada durante el Paleógeno-Mioceno inferior a partir de la inversión de la Cuenca Ibérica extensional mesozoica a partir de compresiones transmitidas desde los márgenes de placa activos (Pirineos y Béticas): una NE a NNE (Eoceno medio- Oligoceno superior) y otra SE a SSE (Mioceno inferior). Este trabajo revisa y examina principalmente las estructuras de inversión asociadas con fallas normales cretácicas que determinaron la división de la Cuenca Ibérica en cuatro dominios paleogeográficos, cada uno fuertemente compartimentado y caracterizado por una particular evolución sedimentaria y estructural. Los ejemplos se relacionan con la inversión de las dos cuencas cretácicas más importantes (Cameros y Maestrazgo), que conllevó asimismo el desarrollo de cuencas cenozoicas (Ebro, Montalbán, Aliaga) cuyos sedimentos han permitido conocer la evolución cinemática de algunas estructuras. Otros ejemplos proceden de estructuras extensionales pérmicas y triásicas. La gran variedad de ejemplos estudiados permite proponer una clasificación de estructuras de inversión para las regiones intraplaca. También, analizar algunos factores que controlaron la inversión de fallas (profundidad del despegue basal, presencia de despegues superficiales, geometría de las fallas extensionales). Asimismo, se ha distinguido modelos de inversión tectónica de piel fina, que involucra o no al basamento, y de piel gruesa. The Iberian Chain is an intraplate mountain range, oblique to the northern (Pyrenean) and southern (Betic) active margins of the Iberian Plate. It developed by positive inversion of the extensional Mesozoic Iberian basin, caused by compression both normal (NNE to NE) and parallel (SE to SSE) to its boundaries. The main, NNE to NE compression (Middle Eocene to Late Oligocene in age) was responsible for the principal folds and thrusts. The SE to SSE compression was mainly active during the Early Miocene, as the convergence between Europe and Africa was transferred from the Pyrenean to the Betic margin of Iberia, though it formed few new macrostructures. This work mainly reviews and examines the inversion structures associated with Cretaceous normal faults that determined the development of four paleogeographical domains into the Iberian Basin, each one characterized by particular structural and sedimentary features, and also divided into subbasins. Examples are mainly related to inversion of the two main Cretaceous basins (Cameros and Maestrazgo), showing different Cenozoic compressional evolution. Associated with basin inversion, the development of coeval Cenozoic continental basins (e.g., Ebro, Montalbem, Aliaga) was produced, their tectonosedimentary relationships allowing to know the kinematics of some inversion structures. Other inversion examples related to Permian and Triassic extensional structures are also reported. The great variety of cases studied along the Iberian Chain allows us to propose a classification of inversion structures that can be extrapolated to other intraplate areas. In addition, this variety of examples has permitted to analyse some of the main factors controlling tectonic inversion and the resulting compressional structures, such as the location (depth) of the main (basal) detachment, usually in Paleozoic basement rocks, the presence of intermediate detachement levels within the cover (mainly Middle and Upper Triassic gypsum and lutites), or the direction and geometry at depth of the previous extensional faults. Based on changes in geometry of the main inversion structures along the chain and its surroundings, thick-skinned, basement-involved thin-skinned, and thin-skinned inversion tectonics have been distinguished. They usually vary from central to marginal parts of major extensional basins that contain an intermediate detachment level within the cover