AN EARLY PLEISTOCENE PLANT ASSEMBLAGE WITH EAST EUROPEAN AFFINITY IN THE VENETIAN-FRIULIAN BASIN (NE ITALY)

Abstract

A palaeobotanical study, including pollen and carpological analyses, has been carried out on the brown coal seam of San Pietro di Ragogna (Friulian foothills). The palynoflora and carpoflora have been analysed with the Plant Community Scenario approach for a better interpretation of their palaeovegetational signals. The coal-bearing layer, despite its limited chronological extension and exposure, is significant for the occurrence of several fossil fruits and seeds belonging to taxa with East European affinity, recorded for the first time in Italy, such as Hypericum tertiaerum, Myriophyllum praespicatum, Najas major-pliocenica, Nymphaea borysthenica, Potamogeton cf. panormitanoides, Schoenoplectus cf. lacustroides. Their concomitant occurrence with Carex cf. elata, Menyanthes trifoliata and Nuphar aff. lutea, which appear in Italian floras after the Piacenzian/Gelasian boundary, points to a Gelasian age of the studied coal deposit. Such hypothesis is also supported by the floristic/vegetational affinities with selected Gelasian floras from Central and Eastern Europe. The coal deposit directly overlays the regional unconformity, ascribed to the Messinian, which marks the base of the Quaternary succession in the Friulian piedmont plain. The geographical location of the site is also significant for the reconstruction of palaeovegetational changes at the Plio-Pleistocene transition. In fact, the occurrence of East European elements may indicate that the migration of plant taxa from Eastern Europe reached the easternmost part of Northern Italy, under the effects of climate worsening related to the inception of glacial periods in the Northern Hemisphere.