Paleobotany of the biogenic unit of the Leffe formation (early Pleistocene, Northern Italy): Brief report on the state-of-the-art

Abstract

This paper briefly summarises the state-of-the-art of the palasobotanical research in the Leffe Basin (N-ltaly), after constitution of a working group in Milan for the revision of the Leffe sequence. A new pollen record, integrated by preliminary macrofossil analyses, has been carried out in browncoal and lacustrine sediments in the middle Leffe sequence (the "biogenic unit" dating to the Early Pleistocene). Several problems araising from the palaeobotanical data are pointed out concerning the paleoenvironment, migration patterns of vegetation, palaeoclimatology and biostratigraphy at the beginning of the Quaternary. Reference is made to specific papers where these problems are examined in more detail. It is noteworthy that several woody plants, extinct in Central Europe since late Pliocene times, were still living in the Leffe mire during the warmest periods at the beginning of the Quaternary. Their record is discontinuous and it is modulated by cyclical climatic changes. Traditional biostratigraphic criteria, mainly based on a supposed progressive extinction of Tertiary plants, meet with substantial difficulties when applied to such rapid and cyclical evolution of vegetation.