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doi:10.2204/iodp.proc.303306.205.2009

Introduction

Planktonic foraminifers have been very useful in elaborating biostratigraphic studies for the Pliocene and Pleistocene in the North Atlantic (Berggren, 1984; Berggren et al., 1985; Weaver, 1987; Weaver and Clement, 1986, 1987; Raymo et al., 1989). Most of these studies are based on the distribution of some species of Globorotaliids, such as Globorotalia puncticulata, Globorotalia margaritae, Globorotalia inflata, or Globorotalia truncatulinoides, as well as Neogloboquadrina pachyderma sinistral or Neogloboquadrina atlantica. Some of these species, however, show a preferential habitat in the temperate and subtropical regions, and consequently their distribution is not synchronous throughout the North Atlantic. This is the case with G. margaritae, which disappeared first from the northern latitudes of the North Atlantic (Weaver and Clement, 1986). Other species, such as G. truncatulinoides or G. puncticulata, are rarely distributed in the northernmost regions of the North Atlantic, and therefore their use is limited to the mid-latitudes.

Globorotaliids were also used to construct biostratigraphic scales in the Mediterranean (Cita, 1973; Iaccarino, 1985). Biostratigraphic events in this region were calibrated to the astronomical timescale through the tuning of rhythmic sedimentary cycles to astronomical solutions (Hilgen, 1991a, 1991b; Lourens et al., 1996a, 1996b, 1998), which gave very accurate ages with a precision lower than a precession cycle.

In this study we performed a quantitative study of some planktonic foraminifer species from Integrated Ocean Drilling Program Site U1313 in order to define and locate the main biostratigraphic events for this site and to compare these ages with the astronomical dates derived from the Mediterranean cyclical sections.

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