The Northeast Alentejo Neoproterozoic-Lower Cambrian succession (Portugal): Implications for regional correlations in the Ossa-Morena Zone (Iberian Massif)

Abstract

The Neoproterozoic-Lower Cambrian succession of the Northeast Alentejo (Portugal) is revised from a stratigraphic perspective in order to propose regional correlations with similar Ossa-Morena Zone domains in Spain. This revision now allows a better characterization of one of the most illustrative Neoproterozoic-Lower Cambrian stratigraphic sections of the Iberian Massif. The Serie Negra Group that is represented in Portugal by the Mosteiros Formation and Besteiros Amphibolites can be correlated with the Tentudia Formation and probably to part of the Montemolin Succession. The Neoproterozoic?- Cambrian transition unit known as the Volcano-Sedimentary Complexes of Nave de Crou-Azeiteiros and Freixo-Segóvia in Portugal are correlationable with the Malcocinado Formation widely distributed within the Ossa Morena Zone in Spain. The uppermost units, attributed to the Lower Cambrian and recognized as the Detritic-Carbonate Complexes of Ouguela and Assumar in the Northeast Alentejo can be correlated with the terrigenous Torreárboles Formation and the carbonate Alconera Formation described in Spain. In the context of the orogenic cycles in Iberia, the concept of Cadomian basement should be enlarged to the Cambrian period