Dinoflagellate cyst evidence of 'Heinrich-like events' off Portugal duringthe Marine Isotopic Stage 5

Dinoflagellate cysts were analysed from IMAGES core MD952042 (37 degrees 48 'N; 10 degrees 01 'W) retrieved from the Tagus Abyssal Plain. Previous resu lts of stable isotope and magnetic susceptibility measurements as well as o f planktonic foraminiferal temperature reconstruction from this core, sugge st the occurrence of "Heinrich-like events" (i.e. large ice-sheet decay) du ring Marine Isotopic Stage 5 (MIS 5). Dinoflagellate assemblages of this ti me period have revealed six dinocyst events that are characterised by peaks in Bitectatodinium tepikiense percentages. These events occur synchronousl y with "Heinrich-like events" previously identified. They are coeval with m ajor retreats of the forest on land, indicating, therefore, drastic changes in the regional climate. However, results from the Ice-Rafted Detritus (IR D) analysis of the >150 mu m lithic fraction shows that MIS 5 of MD952042 h as only recorded one significant input of iceberg discharge, located at the MIS 6/MIS 5 transition. It seems therefore that it is the only event that could be called a "true Heinrich event". (C) 2000 Elsevier Science B.V. All rights reserved.