La extensión Sin~Colisional en la Zona Centro Ibérica: restricciones temporales impuestas por edades U-Pb en monacitas del sector de Somosierra, Sistema Central Español

Abstract

A new integrated analysis of microstructural, metamorphic and U-Pb monazite age data, indicates that the Berzosa-Riaza shear zone (BRSZ) is a major D2 extensional structure associated with crustal-scale ductile extensional shearing and important decompression. Textural relationships and U-Pb dating of monazite in rocks of several structural levels of Somosierra sector, establish that the main D2 extensional event took place in between 337±2 to 326±3 Ma (Early to Mid). This event was associated with the major extensional collapse of the Variscan interland (Central Iberian Zone) and was contemporaneous with the earliest thrusting in the foreland (Cantabrian Zone)