Paleogeographic interpretation of a peat layer at Torson di Sotto (Lagoon of Venice, Italy).

Abstract

A 3.3m long core from the central part of the lagoon of Venice has revealed a peat layer between 1.3m and 2.0m below mean sea level. Pollen analysis indicates the predominance of Quercus and Alnus and the existence of a transgressive phase: the base of the peat (dated 1730 yr BP) was formed in a fresh-water environment, and the upper part (dated 1140 yr BP) in a brackish one. Foraminifera analysis indicate that transgression has preceded a regression. The whole sequence is, from bottom to top: 1) an oligohaline to mesohaline environment (from -3.3 to -2.5m) with very abundant forams; 2) a fresh-water environment (from -2.5 to -2.0m); 3) the 0.7m thick peat layer, becoming gradually brackish; 4) a mesohaline environment (above -1.3m).-from English summary