Precambrian successions in SW Iberia: their relationship to ‘Cadomian’ orogenic events

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Abstract
Despite extensive reworking in Devonian and Carboniferous times, two major deformational events taking place in late Precambrian times may be recognized in the SW Iberian Massif. These have been collectively referred to as ‘Cadomian’ or ‘Pan-African’. The Precambrian successions may be subdivided into pre-orogenic and syn-orogenic groups on the basis of their tectonostratigraphic evolution with respect to the Cadomian orogeny. The pre-orogenic successions (roughly mid-upper Riphean) represent different parts of a miogeoclinal wedge, the basement of which is not known as yet. Polyphase deformation and variable degrees of metamorphism accompanied the first Cadomian event. The syn-orogenic successions (roughly upper Riphean-Vendian) were laid down during and after the first Cadomian event and were in turn deformed and slightly metamorphosed by the second single-phased deformation. These correspond to two distinct types: calc-alkaline igneous successions and flysch-like deposits, that can be interpreted respectively as an orogenic continental arc suite and a foreland basin fill, on the basis of their geochemical and sedimentological characteristics.