Abstract
Late Pleistocene paleoproductivity patterns during the last climatic cycle in the Guyana Basin as revealed by calcareous nannoplankton
Highlights
The small Noelaerhabdaceae, G. oceanica and F. profunda proved to be the dominant species in the calcareous nannoplankton assemblage
This situation would have resulted in a higher primary production and eutrophic conditions, and such a scenario implies the influence of the southeast Trade Winds 10 blowing parallel to the coast (Gibbs, 1980), favoring upwelling and eastward water transport through the well-developed North Equatorial Countercurrent (NECC)
5 Conclusions Variations in the evolution of calcareous nannofossils have allowed us to elucidate 10 changes in the oceanic and atmospheric dynamics in the Guyana Basin; such changes are primarily linked to the southeast Trade Winds
Summary
Introduction and backgroundCoccolithophorids are photosynthetic planktonic algae living in the photic layer of the ocean (Hibberd, 1976, Brand, 1994; Young, 1994; Winter et al, 1994) that play a significant role in carbonate precipitation (Siesser and Winter, 1994; Steinmetz, 1994). 5 The temporal and spatial distribution of coccolithophores may respond to major environmental factors in the upper oceanic layer such as temperature, nutrients, the trophic regime and sunlight levels (Brand, 1994; Young, 1994). 20 The production and sedimentation of coccolith-derived calcite in the deep ocean plays an important role in the carbon cycle through photosynthesis and calcification (Westbroek et al, 1993; Marsh, 2003; Brand, 1994, Young, 1994; Steinmetz, 1994) These organisms are one of the most important contributors to carbonate sedimentation in the open ocean and in continental slopes (Milliman, 1993; Steinmetz, 1994), 25 such as in the Guyana Basin (Shipboard Scientific Party, 2003), an area controlled by a setting of hemipelagic deposition. The northward or southward position of the ITCZ causes a significant impact on water discharge from the Amazon and Orinoco rivers, as well as variations in the direction and speed of the Guyana Current (GC) and the southeast Trade Winds (Muller-Karger, 5 1989; Wilson et al, 2002; Ffield, 2005; Stramma et al, 2005) (Fig. 1)
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