Plio-Quaternary coastal uplift along the western Iberian Margin: insights from dated marine terraces (Peniche, Portugal)

Abstract

This study presents a detailed geomorphological and geochronological analysis of a marine terrace staircase developed into the Peniche Peninsula (Portugal), a rocky headland of Jurassic carbonate bedrock located in the central sector of the Western Iberian passive margin. The marine terrace levels are described morphologically and sedimentologically, but also dated using ESR and U-Series methodologies. The marine terrace staircase comprises six emerged levels ranging from 4 m (above mean sea level, asl) (Tm6) to 24–28 m asl (Tm1), inset into a summit wave-cut platform at 29–45 m asl (Pm). The marine terrace sediments are composed of rounded boulders to cobbles and coarse sands. Dating results reveal that the marine terrace staircase spans ∼900 ka across the Middle-Late Pleistocene. The terraces can be assigned to either a single sea-level highstand or a level that has been re-occupied by two sea level highstands. The staircase records very low uplift rates (0.04 to −0.02 m/ka; the longer-term mean rate for the entire Pleistocene staircase is 0.03 m/ka), typical of a passive continental margin. Regionally, coastal terrace staircases are typically found along the Western Iberian passive margin, with their configuration locally influenced by the underlying bedrock geology and tectonic history.