Late Pleistocene and Holocene evolution of the north Adriatic sea

Abstract

: The Adriatic sea is a modem epicontinental basin where the late Quaternary transgressive deposition shows differentiated sedimentary responses that reflect contrasting physiographic areas as well as differences in the balance between ocean-ographic regime and sediment input during relative sea-level rise. Low shelf gradients (40 m/100 km), and low sediment input with respect to the increasing available space volume, favour significant landward shifts of depositional environments during relative sea-level rise. As a consequence, successive backstepping parasequences do not completely overlap. Furthermore, transgressive deposits are not covered by younger high-stand sediments on large shelf areas and can, therefore, be selectively sampled by conventional gravity and piston coring. Remnants of a complex barrier-lagoon-estuary system rest under the ravinement surface between -30 and -50 m depth. Several AMS 14C dates obtained from peat layers frequently interbedded within these paralic deposits are added to the already large 14C Adriatic database. The new data are in good agreement with the global sea level rise curves, proving their re-liability as sea level indicators. A few samples from peat layers marking the base of the transgressive deposits in the study area between -42 and -52 m depth record the cold event related to the Younger Dryas chronozone (13,000-11,700 calendar years BP; and 11,000-10,000 14C years BP. The bulk of transgressive paralic deposits (barrier-lagoon system) is related to the phase immediately following the last melting water pulse (MWPIB), dated at 11,000 calendar years BP in the northern Atlantic Ocean. The formation of this barrier-lagoon system may reflect increased sediment discharge rates. The good preservation of this coastal system suggests a rapid drowning related to the increased rates of sea level rise observed in global curves between 11,000 and 6,000 calendar years BP. The maximum marine ingression is recorded by lagoonal deposits in land wells and is dated around 5,000 calendar years BP.