Holocene palaeoenvironmental evolution of the Ebro Delta (Western Mediterranean Sea): Evidence for an early construction based on the benthic foraminiferal record

Abstract

Major Mediterranean deltas began to develop during a period between 8000 and 6000 22 yr BP when the rate of fluvial sediment input overtook the declining rate of sea-level 23 rise. However, different authors have argued that the Ebro Delta primarily formed 24 during the Late Middle Ages as a consequence of increased anthropogenic pressure on 25 its river basin and these arguments are supported by the scarcity of previous geological 26 studies and available radiocarbon dates. To reconstruct the environmental evolution of 27 the Ebro Delta during the Holocene, we used micropalaeontological analysis of 28 continuous boreholes drilled in two different locations (Carlet and Sant Jaume) on the 29 central delta plain. Different lithofacies distributions and associated environments of 30 deposition were defined based on diagnostic foraminiferal assemblages and the 31 application of a palaeowater-depth transfer function. The more landward Carlet 32 sequence shows an older and more proximal progradational delta with a sedimentary 33 record composed of inner bay, lagoonal, and beach materials deposited between 7600 34 yr BP and >2000 yr BP under rising sea-level and highstand conditions. This phase 35 was followed by a series of delta-plain environments reflected in part by the Carlet 36 deposits that formed before 2000 yr BP. The Sant Jaume borehole is located closer to 37 the present coastline and contains a much younger sequence that accumulated in the 38 last 2.0 ka during the development of three different deltaic lobes under highstand sea-39 level conditions. The results of the present study reinforce the idea that the Ebro Delta 40 dates to the early Holocene, similar to other large Mediterranean deltas.

Benthic foraminifera and environmental changes in the Quaternary of the western Mediterranean coast: the core of Xeraco, Valencia, Spain

“…Several studies have treated the Quaternary evolution of foraminifera from coastal restricted environments in the western Mediterranean area, but many are limited to the Holocene. In the Iberian Peninsula, this is the case of the Ebro delta (Cearreta et al, 2016), the Vilanova i La Geltrú peat bog (Calzada, 1970), the Peníscola marsh (Usera et al, 2006), the Torreblanca lagoon (Colom, 1959;Collado & Robles, 1983;Usera et al, 1996a), the Albufera of València (Robles et al, 1985;Carmona et al, 2016) or the Albufereta of Alacant (Blázquez & Ferrer, 2003;Ferrer et al, 2005). Although Upper Pleistocene sediments have been preserved in the Albufera of Alcúdia (Mallorca), the studied foraminiferal assemblages are Holocene in age (Viñals & Mateu, 1999).…”

Study of the morphological affinity between two species of benthic foraminifera from restricted environments: Rosalina douvillei (Cushman, 1928) and Trichohyalus aguayoi (Bermúdez, 1935)

“…Trichohyalus aguayoi was originally described in littoral waters in Cuba (Bermúdez, 1935) and later reported in different brackish environments in the Caribbean and the Gulf of Mexico (Arnold, 1954;Boltovskoy & Hincapié de Martínez, 1983;Scott et al, 1991), in the Mediterranean and the Black Sea (Tufesco, 1969(Tufesco, , 1973Lévy, 1982;Albani et al, 1991;Zampi et al, 1996;Foresi et al, 2004), in the Atlantic (Javaux & Scott, 2003) and the Pacifi c coast of North America (Murray, 1991), in Hawaii (Resig, 1974), in South America (Boltovskoy & Vidarte, 1977;Scott et al, 1990) or even in Australia (Albani, 1968), where a very similar species, possibly co-specifi c with T. aguayoi, Trichohyalus tropicus (Collins, 1958), has also been found in non-marine saline lakes (Cann & De Dekker, 1981). In the Iberian Peninsula, this species is limited to the Mediterranean area and has been reported living in the Ebro Delta (Usera et al, 1989;Cearreta et al, 2016) in the Santa Pola Salinas (Zaninetti, 1984) or in the Torreblanca lagoon (Usera et al, 1990b;Arco et al, 1991;Guillem, 2007).…”

Holocene palaeoenvironmental evolution of Saltés Island (Tinto and Odiel estuary, SW Spain) during the Roman period (1st century BC–5th century AD)

“…In the last 20 years, numerous studies were focussed on the Late Holocene geological record of different Spanish estuaries in order to draw the evolution of these complex areas during the last thousands of years. These investigations are usually based on the analysis of continuous cores or exposed sections and the vertical facies distributions and architecture defined in them, as well as in their datings and age models (Dabrio et al 2000;Ruiz et al 2004b;Leorri and Cearreta 2004;Pérez-Arlucea et al 2007;Cearreta et al 2016;Camacho et al 2017).…”