VARISCAN-LATE VARISCAN-EARLY ALPINE PROGRESSIVE EXTENSIONAL COLLAPSE OF CENTRAL SPAIN

The Variscan-late Variscan-early Alpine evolution of Central Spain is characterized by a progressive transition from dominant compressional conditions, towards a generalized extensional regime. This evolution involved four tectonomagmatic stages: 1) a Dl Variscan stage, associated to widespread compression with E-vergent structural elements, except to the NW, where extension and coeval plutonic activity occurred; 2) a D2 Variscan stage, characterized by increasing extension and associated massive magmatism in the center, with compression localized to the margins; 3) a D3 late Variscan stage involving a NS-directed gravitational collapse of the whole area through EW-oriented detachments, within an oval-shaped "plutonometamorphic core complex"; and, 4) a final D4 early Alpine stage characterized by EW extension, giving rise to a Basin & Range-type asymmetric rift to the E.