Introduction

Since the recognition of the displaced behavior of most of the NW Iberian Paleozoic formations (Fig. 1; e.g. Iglesias et al., 1983; Ribeiro et al., 1990), several detailed works have addressed their geometry and kinematics (e.g. Pereira, 1987, Marques, 1993, Arenas et al., 1986; Farias et al., 1987; Martínez Catalán et al., 1997; Clavijo, 1997). Nevertheless, the strain compatibility between the nappes and the autochthon is still debatable. Indeed, the complex interference structural patterns induced by the progressive Variscan tectonic events, the generalized tardi-orogenic granitic intrusions and the later reworking of previous major faults usually obscures such relations. In northern Portugal the SW boundary of the nappes could be continuously followed for more than 50 km, between Vila Real and Torre de Moncorvo cities. This continuity, as well as the presence in both tectonic domains of rheologically similar quartzitic units, made this a suitable place for understanding its evolution during the first and main pervasive Variscan event. In this paper, the geometry and kinematics of two small critical regions representative, respectively, of the autochthon and adjacent parautochthon sectors, are studied in detail. The obtained data led to the proposal of a dynamical model concerning the emplacement of the Variscan nappes in northern Portugal.

Figure 1. Location Map

Location Map

The NW Iberian allochthonous units and the studied regions (modified from Ribeiro et al., 1990 after new data compiled from Clavijo, 1997 and Arenas et al., 2000).