Late-Holocene coastal dune system evolution in the Danube delta, NW Black Sea Basin

The largest dunefields in the Danube delta developed during the Late-Holocene on the Caraorman and Letea beach ridge plains. Our research focused upon the reconstruction of aeolian landforms in the Danube Delta. Field based investigations of the modern aeolian morphology revealed the succession of different aeolian activity phases shaping the modern aeolian landforms. One phase of aeolian modification of the landforms occurred during conditions of generally low rugosity (bare and grassy areas) while another one followed when the development of aeolian landforms was constrained by the emplacement of woody vegetation. Optically stimulated luminescence (OSL) ages were used in order to develop a chronology of aeolian activity in the Danube Delta during the Late-Holocene. The OSL ages indicate that the interplay between sea-level, sediment availability and climate variability over the last 2400 years resulted in a dunefield pattern containing several dune generations. Moreover, our OSL ages together with the ages produced by Giosan et al. (2006) lead to a new hypothesis for the development of the Letea complex ridge plain, according to which at least three phases with different rates of progradation occurred: (1) rapid rates at the beginning, between 3640 ± 140 yrs to 2300 ± 420 yrs ago, (2) slow rates from 2300 ± 420 yrs to 900-1200 yrs ago and (3) rapid rates since 900-1200 yrs ago until the initiation of the Chilia secondary delta.