ABSTRACT Detrital zircon U-Pb geochronology has been widely used to constrain the pre-Carboniferous geography of the European and, to a lesser extent, the Moroccan Variscides. The latter have been generally considered as part of a long-lasting passive margin that characterized northern Gondwana from Ordovician to Devonian time, and was subsequently involved in the late Paleozoic Variscan orogeny. We report detrital zircon ages for three Early to Late Ordovician samples from the Beni Mellala inlier in the northeastern part of the Western Moroccan Meseta in order to discuss the temporal evolution of the sources of sediments in this region. The detrital zircon spectra of these samples, characterized by two main populations with mean ages of 630–610 Ma and 2170–2060 Ma, are typical of Cambrian–Devonian rocks from the Moroccan Variscides and confirm their link to the West African craton. A minor Stenian–Tonian population (peak at ca. 970 Ma) suggests the influence of a distant and intermittent NE African source (Sahara metacraton), which was probably interrupted after Ordovician time. Our data support previous interpretations of the Moroccan Meseta (and the entire northern Moroccan Variscides) as part of the northern Gondwana passive margin. The main sources of these sediments would have been the West African craton in the western regions of the passive margin (Moroccan Meseta and central European Paleozoic massifs), and the Arabian-Nubian Shield and/or Sahara metacraton in the eastern areas (Libya, Egypt, Jordan, central and NW Iberian zones during Paleozoic time), where the 1.0 Ga detrital zircon population is persistent throughout the Ordovician–Devonian time span.

Abstract In the South Portuguese Zone (Iberian Massif), thin-skinned tectonics linked to the collision with the Ossa-Morena Zone produced the inversion of previous extensional basins in Carboniferous times. Its central domain, namely the Iberian Pyrite Belt, underwent two deformation phases at mostly low-grade metamorphic conditions linked to a progressive deformation migrating upwards from a basal detachment and from north to south. The Puebla de Guzmán Antiform is one of the most outstanding cartographic structures in the Iberian Pyrite Belt, representing a imbricate fan thrust system developed during the second regional deformation phase. In the Puebla de Guzmán Antiform, the first deformation phase gave rise to a penetrative slaty cleavage (S 1 ), which is also recognized in the whole Iberian Pyrite Belt and constitutes the main foliation all over the region. Its genesis is possibly linked to the coetaneous development of thrusts at deeper crustal levels and SSW-vergent folds at all levels above these thrusts. First phase structures were deformed by large-scale imbricated thrust systems with lateral (NNE–SSW) and frontal (WNW–ESE) ramps, which constitute the most relevant regional cartographic structures. This second deformation phase generated thrusts, two set of folds with WNW–ESE and NNE–SSW-oriented axes, as well as two related axial plane crenulation cleavages. These relatively brittle to ductile-brittle second phase structures have been identified in many areas of the Iberian Pyrite Belt, and especially in the southern limb of the Puebla de Guzmán Antiform. The second phase thrusts reported from the Puebla de Guzmán Antiform have not been folded according to both the geological map of the area and the analysis of maximum shortening and stretching axes.

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