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doi:10.2204/iodp.proc.303306.211.2010

Introduction

Coccolithophores are a major group of marine, unicellular phytoplankton, composed of calcareous plates (coccoliths) that form an important part of the fine-grained deep-sea sedimentary record and therefore are extensively used in biostratigraphic, paleoecologic, and paleoceanographic studies (e.g., Sato et al., 1999). In addition, coccolithophores have recently gained increased attention, as they make an important contribution to oceanic primary production. Their biogeographical distribution appears to be especially related to water temperature and nutrient concentration, as does their preservation (e.g., Okada and Honjo, 1973). In addition, shifts in species composition observed in several sediment cores have been attributed to changes in upwelling and sea-surface current systems.

In the present report, we present coccolith data over the last 550,000 y from Integrated Ocean Drilling Program (IODP) Site U1308 in the North Atlantic Ocean. This time interval contains a globally expressed climatic change, the Mid-Brunhes Event (MBE), centered at ~400 ka and likely forced by orbital eccentricity (Jansen et al., 1986; Pisias and Rea, 1988; Crowley and North, 1991).

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