TERMINAL CRETACEOUS WARMING EVENT IN THE MIDLATITUDE SOUTH ATLANTIC-OCEAN - EVIDENCE FROM POLEWARD MIGRATION OF CONTUSOTRUNCANA-CONTUSA (PLANKTONIC-FORAMINIFERA) MORPHOTYPES

Spatial and temporal patterns in test size and shape (test conicity an d spiral roundness) and absolute abundance (accumulation rate) of the planktonic foraminifer Contusotruncana contusa were studied in the Sou th Atlantic Ocean (DSDP sites 356, 516, 535 and 527) during an interva l corresponding to the last 800 kyr of the Cretaceous. The variation i n absolute abundance of C. contusa was characterised by alternating pe riods of high and low abundance; some of these periods were traceable across the entire mid-latitude South Atlantic Ocean. While the mean sp iral roundness did not show any interpretable patterns, a sudden incre ase of the mean test size and mean test conicity occurred between 65.3 and 65.2 Ma (based on linear interpolation within the Cretaceous part of Subchron C29R) at all sites studied, indicating a poleward migrati on followed by rapid withdrawal of the low-latitude C. contusa morphot ypes from the mid-latitude South Atlantic Ocean. We suggest that this event was caused by a short period of surface-water warming in the sou thern mid-latitudes corresponding to the brief high-latitude warming e vent and associated faunal migrations in the Boreal and Austral realms . (C) 1998 Elsevier Science B.V.