La deformación en los bloques de techo y muro de los cabalgamientos de las unidades inferiores Nevado-Filabrides (Cordilleras Béticas, SE. España)

Abstract

In the Nevado-Filábride complex, in the Western sector of the Sierra de Filabres, three tectonically superimposed units can be distinguished. The internal structure of these units corresponds 10 large folds with development of subtantial overturned limbs. This internal structure has been produced by three important deformation phases, which gave rise to more or less penetrative minor structures. The first deformation phase DI gives rise to a slaty cleavage and wouId generate great overtumed folds. The second deformation phase D, gives rise to ductil shear zones with aplanar-linear fabric, and ends up with fragil thrusts which superimposed the different units. The third deformation phase generates South vergent folds that affect all the previous structures. Geometric relations between thrust surfaces and foliation or bedding between the hanging and footwall show the existence of ramps and flats with respect to hanging and footwalls. In adittion to this, there is a considerable contrast with regard to the value and nature of the strain as shown by the rock volumes superimposed by the thrust surfaces, with footwalls rocks less deformed than hanging wall rocks. These thrusts start under sinmetamorphic conditions with deformation caused by ductile and heterogeneous shear and end up in fragile conditions accompanied by strong metamorphic retrogradation.