Palaeostress evolution of the Iberian Peninsula (Late Carboniferous to present-day)

Abstract

Three main stages can be differentiated in Iberia from the Upper Carboniferous to the Present: the end of the Variscan orogeny (Late Carboniferous), the Permian–Early Cretaceous rifting and the Alpine orogeny (Late Cretaceous to Present). In this contribution, the main features of the stress fields determined in each of these stages are compiled and revised from the analysis of the brittle deformations, mainly microfault population. Stresses are related to the development of the principal structures of each stage. In the Late Variscan fracturing stage, sinistral strike–slip faults prevailed in a stress field with NE–SW subhorizontal compression. In the Permian-to-Early Cretaceous rifting stage, the extensional trends varied in each sector. During the Alpine orogeny, primarily the margins of the Iberian Massif (the Betic and Pyrenee mountain chains) were deformed. However, numerous deformations are also identified in its interior, where large mountain chains such as the Central System and the Iberian Chain developed. These deformations occurred in a complex stress field where zones of NW–SE to NNE–SSW horizontal compression prevailed, albeit predominantly extensional zones existed as well. At present, the stress field in most of Iberia has a NW–SE compressive trend, associated with active deformations in the Betic Cordillera, where a continental subduction developed. However, simultaneously, there are zones in which extensional settings predominate, such as the Internal Zones of the Betic Cordillera and the Gulf of Valencia region, making for quite a complex current stress field.