North Atlantic (Rockall Plateau) coccolith assemblage data for MIS 5 of ODP Hole 162-980B

Calcareous nannoplankton analyses on late quaternary sediments from the eastern North Atlantic ODP Site 980 (55°29'N, 14°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 coccolith 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 in coccolith accumulation rates and a change from a less to a higher diverse species assemblage indicate a rapid increase in 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 5.4 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 coccolith 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 stadial events MIS 5.4 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.

(Table 2) Varimax factor matrix of planktonic foraminifera at DSDP Hole 72-517

Quaternary sediments were recovered at all four Sites at Leg 72. Planktonic foraminifers were abundant and well preserved, especially in the holes shielded from Antarctic Bottom Water (AABW) influence. The fauna belonged to the subtropical province marked by Globigerinoides ruber and to a lesser extent by Globorotalia inflata. Thirty planktonic foraminiferal species were distinguished, and a detailed study of the Site 517 stratigraphy was made. The Quaternary sequence of the Rio Grande Rise was subdivided slightly differently from the Bolli and Premoli Suva (1973) pattern. Five subzones were identified but some difficulties arose when a precise correlation became necessary in the subzones of the tropical provinces. Correlations could nevertheless be made, particularly with respect to the earliest Quaternary. Quaternary faunal data have been dated by isotopic stratigraphy (Vergnaud Grazzini et al.,1983) and partially contradict results previously published for this part of the Atlantic (Williams and Ledbetter, 1979). By studying the occurrence of planktonic foraminifers, we obtained more information about hydrologic variations during the Quaternary sequence of Hole 517; two broad periods were recognized. Finally, we identified the interaction between the Brazil Current and the subtropical convergence