Morphological and palaeoenvironmental evolution of the Vendicio coastal plain in the Holocene (Latium, Central Italy)

Morphological, stratigraphical and paleoecological studies carried out along the Vendicio coastal plain (southern Latium) allowed us to reconstruct the paleoenvironmental evolution of the plain in relation to Holocene sea-level changes. On the basis of altitude, texture, microfossil and pollen content of sediments recovered in a 20 m borehole carried out on the backshore, three main transitional palaeoenvironments were recognised. Particularly, the 14C dating of a peat layer at the boring base (-16 m a.s.l.), interbedded between sandy silt with organic matter and silty peat levels, gives an age of 7620 ±100 yr BP, equivalent to 8354-8524 cal yr BP. Over these deposits, sands with pebbles, sometimes alternated with silt and sandy silt levels, lay. Microfossil content, together with sediment features, confirms a transitional sequence from marsh (oligohaline) to lagoon (mesohaline-polyhaline), and finally to marine (littoral) environment, probably due to the last sea ingression related to the mid-Holocene Climatic Optimum peak (~6000 years BP). Pollen analysis reveals the existence of a deciduous forest association, rich in high-humidity demanding elements, by now not represented by a regional modern analogue. The present altitude of the dated peat level, correlated with the available eustatic curves, suggests that the Vendicio sedimentary succession probably has been affected by a slight subsidence phase during MIS 1. The occurrence of a slight subsidence may be also related to late Quaternary vertical displacement of adjacent coastal sectors, and fits in with recent morphological evolutionary models of other minor coastal plains of Latium.