Paleolandscape evolution along the coasts of the Baixo Alentejo (Portugal) during the Quaternary

Abstract

A detailed geomorphological mapping allowed to understand the complex relationships interplayed between local tectonics and sedimentation across the coastal area of the Baixo Alentejo (Portugal) all along the Quaternary. Different outcrops of coastal sediments between Sines and Vilanova de Milfontes permitted to reconstruct a general sequence of up to fifteen stair-cased marine terraces, while wide sequences of alluvial fans develop in the hinterland. The distinct geomorphological disposition of these alluvial fans together with the presence/absence of marine terraces, have allowed to define different phases of paleolandscape evolution based both in sea level changes and differential uplift. A dune system has been attributed to MIS 5e in basis of OSL, and 14C and U-series dating permitted the adscription of a beach unit to MIS 5. These data allowed to stablish the relative chronology of the entire marine terrace sequence and to determine the vertical movement rates along the studied coastal area. The results give values ranging from slight uplift (+0.015mm/a) to subtle subsidence (−0.030 mm/a), coinciding with other author's determinations.