Evidence for Pleistocene wet aeolian dune and interdune accumulation, S. Pedro da Maceda, north‐west Portugal

Abstract

Outcrops and cored/counter‐flushed boreholes in the coastal area between Espinho and Aveiro (north‐west Portugal) were investigated to reconstruct the changing patterns of sedimentation during the Late Pleistocene–Holocene. To obtain a common comparison basis, the grain‐size data from outcrop and borehole samples were analysed. The outcrops and the cored parts of the boreholes were dated by radiocarbon and optically stimulated luminescence. The results show that, on top of pebble‐rich beds of fluvial origin, a wet aeolian dune and interdune environment was active during the later part of the Pleistocene, turning to dry aeolian at the transition to the Holocene. The data indicate also that aeolian accumulation was controlled by vegetation changes (climate) and groundwater table fluctuations. During the Holocene, a podzol formed on the Pleistocene dunes and extensive vegetation precluded major aeolian accumulations. Remobilization of sand started again because of human deforestation and – last but not least – the Little Ice Age.

Characterization and dating of coastal deposits of NW Portugal (Minho–Neiva area): A record of climate, eustasy and crustal uplift during the Quaternary

“…The S. Domingos Sands and Silts (U10) and the Ribeira de Portela Sands (U12) reveal climatic conditions favourable to edaphogenesis (U10) and fluvial drainage reestablishment (U12), which may have occurred between z 32 and z 28 ka. This evidence agrees with Granja et al (2008), who reported successions of small fluvial systems progressively covered by wet aeolian accumulations during the first half of MIS 3. Pérez-Alberti et al (2009) described paleosols on the Galician coast, dated between z 32 and z 25 ka.…”

“…Later, other studies were carried out by Alves (1989Alves ( , 1995Alves ( , 1996 and Meireles (1992). In the adjacent coastal areas of Galicia and Neiva-Aveiro, several studies on the Pleistocene and Holocene deposits were also made: Granja (1990), Granja and Carvalho (1991, 1993, Carvalho et al (1995Carvalho et al ( , 2006, , Granja et al ( , 1999Granja et al ( , 2008Granja et al ( , 2010, Granja (1997, 2003), Groot and Granja (1998), Pérez-Alberti et al (1998), Pagés (2000, 2007), Blanco-Chao et al (2002, 2003, Fábregas Valcarce et al (2003), Araújo (2001Araújo ( , 2004Araújo ( , 2005Araújo ( , 2008, Araújo et al (2003), Garcia-Amorena et al (2007), Thomas et al (2008), Araújo and Gomes (2009) and Ribeiro et al (2010Ribeiro et al ( , 2011. This paper focuses on the geomorphological and sedimentological characteristics of a Pleistocene coastal terrace staircase of NW Portugal, covered by extensive late Pleistocene to Holocene sedimentary units.…”

Climate-driven episodes of dune mobilization and barrier growth along the central coast of Portugal

“…In addition, a podzol was deposited on the Pleistocene dunes located along Espinho -Ovar between 2.7 and 2 cal ka BP, suggesting reduced aeolian activity (Fig. 1) (Granja et al 2008). These results suggest the onset of several lagoonal environments over time, although it is not clear whether there was a single barrier extending alongshore the entire bay or several barriers enclosed the documented lagoons.…”

“…Alternatively, evidence of ephemeral lagoons and landwards shoreline translation during the mid-late Holocene have been reported along the north-central coast of Portugal (Granja et al , 2008(Granja et al , 2010Granja 1999Granja , 2000Bernardes & Rocha 2007;Danielsen et al 2012). These results suggest a scenario of barrier evolution for highenergy and linear coasts characterized by landwards shoreline translation since the mid Holocene, when sea level reached its present position (Vis et al 2010a;Leorri et al 2013).…”

“…The time interval between both aeolian episodes represents a hiatus coincident with the deposit of lagoonal sediments along Furadouro-Torreira around 2 cal ka BP (Bernardes & Rocha 2007) and at Silvalde at about 2.7 cal ka BP . In addition, a podzol was formed on the Pleistocene dunes located along Espinho-Ovar between 2.7 and 2 cal ka BP, suggesting reduced aeolian activity (Granja et al 2008).…”