A beach-ridge progradation complex reflecting periodical sea-level and climate variability during the Holocene (Gulf of Almerı́a, Western Mediterranean)

Abstract

AbstraetDetailed mapping based on aerial photographs at various scales, analysis of morpho-sedimentary units, and radiocarbon dating of the prograding beach-ridge complex of Campo de Dalías (Almería) allow the differentiation of six prograding units, These are called: H¡, 7400-6000 cal BP; H2, 5400-4200 cal BP; H3, 4200-3000 cal BP; H4, 2700-1900 cal BP; Hs, 1900-1100 cal BP; and H6, 500 cal BP-Present. H-units are deposited during periods of high relative sea level and increased sediment input to the coast. They are bounded by large swales or erosional surfaces associated with lower sea levels and reduced input 01' sediment to the coast; these correspond to short periods 01' increased aridity inside the general arid trend recorded in the Westem Mediterranean since 5.4 ka. Changes in the flux 01' Atlantic superficial waters into the Mediterranean Sea, and relative strength of the W/SW winds account for the recorded oscillations of relative sea leve!.We deduce a decadal periodicity for the deposition of a beach ridge and the adjacent swale, and suggest that it is related to fluctuations of the North Atlantic Oscillation (NAO) index and to variations of solar activity. The duration of H-units shows a quasi-millennial periodicity punctuated by short (hundred years) episodes of reduced progradation or erosion representing events of increased aridity likely to be related to Bond's Holocene cold events.

The coastal archives of the last 15ka in the Atlantic–Mediterranean Spanish linkage area: Sea level and climate changes

“…The value is significantly similar to the 400 500 a calculated for areas of the North Atlantic affected by the Gulf Stream by Harkness (1983), Stuiver et al (1986), Bard (1988), Southon et al (1990). In the Mediterranean samples, Goy et al (2003) used the value proposed by Sanlaville et al (1997) of 400 years for the reservoir effect in the Mediterranean, very close to the 402-year figure given by Stuiver and Braziunas (1993), which is currently incorporated in the calibration software used. Calibration of radiocarbon ages was performed using the CALIB Program and its revised version (Stuiver and Reimer, 1993;Stuiver et al, 1998).…”

“…Radiocarbon data available from previous authors are used (Rodriguez-Ramirez et al, 1996;Zazo et al, 1999bZazo et al, , 2005Dabrio et al, 2000;Lario et al, 2002;Goy et al, 2003). Usually, sediments were dated by accelerator mass spectrometry (AMS) and conventional radiocarbon techniques applied on mollusc shells: Glycymeris glycymeris in beach and barrier systems, the available molluscs and wood fragments in estuaries, and charco al in aeolian dunes.…”

“…lOa and b) includes part of H s , as age of the oldest exposed beach ridges is 1800 cal a BP, and H6 (sensu Goy et al, 2003). Analysis of beach ridges morphology, age, and distribution reveals that sets of four beach ridges, similar to o 2Km.…”

“…1). Much information comes from coastal sectors studied in previous papers (e.g., Zazo et al, 1994Zazo et al, , 1999aZazo et al, c, 2005Borja et al, 1999;Dabrio et al, 1999Dabrio et al, , 2000Goy et al, 1996Goy et al, , 2003Lario et al , 2000Lario et al , , 2002Luque, 2002;YIl et al, 2003), and from Doñana-Huelva (Rodrí-guez-Ramírez et al, 1996Ruiz et al, 2005;Cáceres et al, 2006). The paper also ineludes data from Portuguese (Bard et al, 2000); M39-008 (Cacho et al, 2001; MD95-2043 (Cacho et al, 1999(Cacho et al, , 2001Sánchez-Goñi et al, 2002);H-658 C (de Menocal et al, 2000).…”

“…8c). Changes in set configuration, occurrences of particularly wide swales (or gaps) or erosional surfaces truncating the systerns of beach ridges, and changes in the orientation of ridges and swales led Goy et al (2003) to identify six prograding units or groups of sets (H-units) that began prograding, ca. 7400 cal a BP (Figs.…”