Changes in palaeoceanography and palaeoecology during Marine Isotope Stage (MIS) 5 in the eastern North Atlantic (ODP Site 980) deduced from calcareous nannoplankton observations

Calcareous nannoplankton analyses on late quaternary sediments from the eastern North Atlantic ODP Site 980 (55 degrees 29'N, 14 degrees 42'W) provide detailed insight into palaeoceanographic and palaeoclimatic changes that occurred throughout the Termination II and the adjacent interglacial of the Marine Isotope Stage (MIS) 5. This study presents the development of the coccolah assemblage throughout the interglacial MIS 5 towards the beginning of the glacial MIS 4 in the vicinity of the Rockall Plateau and investigates and characterises the impact of climatic and environmental variations on the coccolith assemblage distribution between 135 and 65 ky In general, the coccolith assemblage is dominated by Gephyrocapsa muellerae and Emiliania huxleyi, whilst significant changes in palaeoceanographic and palaeoclimatic conditions are mainly shown by variations of subordinate species A drastic increase m coccolith accumulation rates and a change from a less to a higher diverse species assemblage indicate a rapid increase m surface water temperatures during the onset of MIS 5 from c. 127 5 ky on. Highest coccolith numbers, high numbers of taxa and a large diversity indicate highest coccolithophore primary productivity and peak interglacial conditions during MIS 5.5, which are due to the high influence of relatively warm surface water to this region. Coccolith numbers peak again around 120 ky and decline afterwards but stay above glacial levels. The two cooling events of MIS 54 and 5 2 interrupt the generally warm conditions and are indicated by lowered coccolith numbers, a drop of thermophile species and a reduction of the species diversity. Decreasing coccolah numbers and a slightly reduced diversity indicate that environmental conditions deteriorated towards the onset of MIS 4 The analysis of the coccolith assemblage reveals that not only the stadia! events MIS 54 and 5 2 are characterised by colder conditions, but furthermore confirms the upcoming notion that MIS 5.5 was terminated by a slight short-term cooling of the surface water which occurred around 124 ky (C) 2010 Elsevier BV All rights reserved