POLLEN DATA FOR A BIOSTRATIGRAPHY OF LGM IN THE VENETIAN PO PLAIN

Abstract

During the last forty years many works have been published on sedimentary sequences from the planitial area of north-eastern Italy.
Many Authors refer about stratigraphic sequences which contained peat layers at different depths from the ground level. Radiocarbon
dating of peats has been given ages ranging from 22,500 to 18,000 yr BP. The area with suitable conditions for the formation of peat,
seems to cover all the Venetian planitial area for a brief period of time during the LGM. We are interested in the microfossil content of
LGM peats, because it can contribute to the definition of past local hydrological conditions. We would like to answer to the following
questions: i) can we say that the same type of vegetation has formed the LGM peats? ii) can we hypothesize that the same hydrological
conditions were established during LGM in the plain? iii) can we use the peat horizon as a biozone for the Venetian Plain? We approach the topic by analysing new pollen data of peat sediments from a coastal area at the north of the Venice Lagoon, by means of a new
statistical method of data analysis, namely the NonParametric Combination of Dependent Permutation (NPC) Tests (Pesarin, 2001).
The statistical analysis of pollen data does not include the pollen records from other sites (Tab.1), since they are not entirely reported in literature; therefore a successful comparison was not achievable. The NPC Test results confirm that there aren’t significant differences between the peat sediments. Hence we can assert that the area was mostly covered by Cyperaceae and Poaceae, and this confirm our hypothesis. Some other herbaceous taxa were present and many taxa of Fungi, Algae and Mosses. Studies for the identification of the latter and other plant fragments are in progress and they will lead to a finer characterization of the plant community.