The Iberian Massif provides the largest outcrop of Variscan and pre-Variscan rocks in Europe (Fig. 2.1a). It has been divided into several zones (Fig. 2.1b) and, within the Spanish part of these zones,extensive areas are occupied by Precambrian rocks (Fig. 2.1c). These Neoproterozoic successions are known under informal and local stratigraphic names so that it is not easy to provide a comprehensive synthesis of the Precambrian in Spain to a wide audience. Additional difficulties arise because different authors have focused their attention on different aspects (stratigraphy, petrology, tectonics, etc.) in widely separated geographic areas. Furthermore, widespread overprinting by Palaeozoic igneous and medium- to highgrade metamorphic processes has erased much sedimentological data and obscured correlations within and between Precambrian areas. As a consequence, many different local names have been proposed for stratigraphic units that are partially coincident with units in other localities. Thus, readers unfamiliar with geographic names may become discouraged when trying to compare and understand Precambrian stratigraphy from area to area in the Iberian Massif. To help readers, the names of the stratigraphic units and correlations across the zones are summarized in Figures 2.2 and 2.3.
Correlation chart of lithostratigraphic units from the Upper Neoproterozoic–Lower Cambrian in the different zones of the Spanish Iberian Massif. The Neoproterozoic–Cambrian boundary according to Bowring & Erwin (1998). U-Pb isotopic data after Lancelot et al. (1985), Schäfer et al. (1993), Ordóñez (1998), Fernández Suárez