Past low-latitude climate changes are still under considerable debate. Different techniques to extract past sea-surface temperatures are being used, yet all are subject to potential errors and uncertainties. The best approach is to use a multitude of techniques; however, it is prohibitively time consuming. Therefore, at this stage, we present the stable isotope record of Site 1006 to obtain a first impression of climate variability in the low-latitude northern Atlantic, with the intention of producing additional proxy records in the future.
Site 1006 was drilled in 658 m of water in the northern portion of the Santaren Channel, ~30 km from the western platform edge of the Great Bahama Bank (Fig. 1). It is the most distal member of the five transect sites located westward of the Great Bahama Bank, positioned on a thick sequence of Neogene-age drift sediments. The drift sediments interfinger with neritic material derived from the carbonate platform. The result is an expanded section suitable for paleoceanographic studies because of its high temporal resolution. The advanced hydraulic piston corer (APC) system was used to retrieve the Neogene sequence, of which the upper seven cores of Hole 1006A were studied. The cores include 166-1006A-1H through 7H, which cover the upper 65 m of sediment.
The age model for Site 1006 was constructed by directly correlating its stable oxygen isotope record to the astronomically tuned record of Site 806 from the western equatorial Pacific (Berger et al., 1993). This provided the opportunity to make direct comparisons between different oceans in the low latitudes to highlight similar and dissimilar features of both records as a response to glacial/interglacial variability. As we shall show, the low-latitude glacial/interglacial variability is about twice as large, or even larger, in the Atlantic than in the western Pacific throughout the last 1.4 m.y.
Site 1006 is situated in an interesting position in 'the source area of the Gulf Stream' and thus the stable oxygen isotope record reflects its sea-surface conditions. The Gulf Stream originates from the western equatorial Atlantic, and its low-latitude variability may have possibly influenced northern-latitude climate variations. We shall show that considerable interglacial warming has taken place since stable oxygen isotopic Stage 11. Transport of additional heat into the North Atlantic during the last five interglacial periods may have contributed to the rapid melting of the large ice sheets that developed during the late Quaternary glacial periods.
Finally, the platform production of the Great Bahama Bank is explored at this site as a response to sea-level changes and sea-surface conditions. This is more fully explained in the chapter by Rendle et al. (Chap. 6, this volume). Here we use the aragonite records to aid in the reconstruction of the age model because the aragonite cycles perfectly match those of the stable oxygen isotope record and are sometimes better developed than the oxygen isotope cycles.