LATE PRECAMBRIAN SERIES AND STRUCTURES IN THE NAVALPINO VARISCAN ANTICLINE (CENTRAL IBERIAN PENINSULA)

The Navalpino Anticline is a major Variscan structure in the Central I berian Zone of Spain. Three lithological groups are defined in the pre -Ordovician rocks of this anticline. The Rifean or Lower Vendian Extre meno Dome Group is unconformably overlain by the Upper Vendian Ibor-Na valpino Group. This fatter group presents two different facies separat ed by a NW-SE trending synsedimentary fault. The Lower Cambrian Valdel acasa Group unconformably overlies both the Extremeno Dome and the Ibo r-Navalpino Groups. Three pre-Variscan episodes of deformation have be en defined in the area of the Navalpino Anticline. A major asymmetrica l fold with a subvertical east-west-striking limb is the result of the first deformation event of pre-late Vendian age. The second deformati on event is of Cadomian (Late Precambrian) age and is composed of two stages; (i) an early extensional stage including NW-SE trending extens ional fault and basin development in the north-eastern block; and (ii) a second compressive stage giving rise to north-south trending uprigh t folds. This second compressive stage possibly inverted the basin. A final pre-Variscan deformation event took place between the Early Camb rian and the Early Ordovician resulting in a 5-10 degrees tilting to t he north-east. There are two main phases of Variscan deformation in th e area. The first deformation event (D-v1) gave rise to a upright WNW- ESE trending folds on all scales, whereas the second (D(v)2) gave rise to a brittle-ductile sinistral strike-slip shear zone tending subpara llel to the axial trace of the D(v)1 folds.