DINOFLAGELLATE CYST STRATIGRAPHY OF THE EOCENE-OLIGOCENE TRANSITION IN CENTRAL ITALY

Eight dinoflagellate cyst zones based on the Massignano and Monte Cagn ero sections in central Italy provide high-resolution control for the Eocene/Oligocene (E/0) transition. Most of these zones have been recog nized in the time-equivalent Contessa Highway section and are calibrat ed against previously established magneto- and biostratigraphies. The invasion of the Mediterranean area by several higher-latitude dinoflag ellate taxa marks the E/O boundary as characterized by the last occurr ence of the hantkeninids (planktic foraminifers), calibrated against a horizon just above the youngest normal polarity event within Chron C1 3R. Quantitative and qualitative dinoflagellate events across the E/O boundary allow the recognition of warmer and cooler successive interva ls of sea surface temperature, in addition to apparent sea-level fluct uations. Our data indicate that latest Eocene warm conditions and a se a-level highstand were rapidly replaced by short-term cooler condition s and a lowstand across the E/O boundary horizon. Following a short-te rm warmer interval and a highstand during the earliest Oligocene, a se cond cool and lowstand episode occurred. This cool interval was of gre ater magnitude and duration than the one at the E/O boundary horizon a nd may correspond to the globally recognized cooling event reported fr om the basal part of Chron C13N.