Tectono‐Sedimentary Phases of the Latest Cretaceous and Cenozoic Compressive Evolution of the Algarve Margin (Southern Portugal)

Abstract

The latest Cretaceous and Cenozoic tectono-sedimentary evolution of the central and eastern Algarve margin (southwestern Iberia) is reconstructed as a series of structural maps and three-dimensional diagrams based on multichannel seismic reflection data. Six seismic stratigraphic units, bounded by unconformities related to tectonic events during the African–Eurasian convergence, have been identified. Several episodes of major regional change in palaeogeography and tectonic setting are distinguished: they occurred in the Campanian, Lutetian, Oligocene–Aquitanian transition, middle Tortonian, Messinian–Zanclean transition and Zanclean–Piacenzian transition. These changes were induced by geodynamic events primarily related to the relative motions of the African and Eurasian plates. The Late Cretaceous and Cenozoic in the Algarve margin were dominated by compressional deformation. Triggered by the regional tectonics that affected the basement, Upper Triassic–Hettangian evaporites played an important role in tectono-sedimentary evolution by localizing both extensional and thrust detachments and generating both salt structures and salt-withdrawal sub-basins. During middle Eocene and Oligocene times, coeval development of compressive structures and normal fault systems in the eastern Algarve domain is interpreted as resulting from gravity gliding due to a general tilt of the margin. The increasing effects of the African–Eurasian convergent plate boundary zone resulted in the uplift of some areas, overprinted by an increasingly general subsidence of the domains studied.