Sites 1003 and 1006 were drilled on the prograding western margin of the Great Bahama Bank during Ocean Drilling Program (ODP) Leg 166. Both sites lie along a platform-to-basin transect that connects the shallow bank with the deeper water areas. This transect was positioned on the "Western Geophysical seismic line" studied previously by Eberli and Ginsburg (1987, 1989) (Fig. 1). The more proximal site, Site 1003, represents the middle-slope sediments and is situated ~4 km from the platform edge at a water depth of 481 meters below sea level (mbsl). Site 1006, in contrast, is the most distal site along the transect located basinward in the northern portion of the Santaren Channel ~30 km from the platform edge at a water depth of 658 mbsl. This site was designed to (1) provide an independent indicator of sea level because of its greater pelagic component, and (2) through sequence stratigraphy, aid in the dating of the proximal sites where the chronostratigraphy is occasionally unclear. This lack of clarity could be the result of missing sequences because of erosion and/or poor recovery, and diagenesis and/or dilution by neritic sediments (Eberli, Swart, Malone, et al., 1997).
The sediments in the interval studied (0-77.5 meters below seafloor [mbsf]) at Site 1003 are Pleistocene to Holocene in age and consist primarily of unlithified to partially lithified mudstones to floatstones and minor nannofossil oozes, which contain approximately equal amounts of platform-derived mud and calcareous sand mixed with pelagic carbonate components (i.e., periplatform ooze; Schlager and James, 1978). Peloids and aragonite needles are also major components through this section. This sediment interval lies within lithostratigraphic Unit I (0-162.1 mbsf; Eberli, Swart, Malone, et al., 1997). The upper interval (0-59.9 mbsf) is thought to show a change from pelagic-dominated input in the lower section of the interval to a strong input of coarse particles in the middle to upper part that are derived from the shallow carbonate producing area (Eberli, Swart, Malone, et al., 1997). The lower interval (59.9-162.1 mbsf), in contrast, consists of an alternation of coarser and finer grained intervals that are relatively rich in platform-derived components. A downcore disappearance of peloids was also observed.
The sediments in the interval studied at Site 1006 (0-65 mbsf) are Pliocene to Holocene in age and consist of largely unlithified, bioturbated nannofossil ooze (with sand- and silt-sized foraminifers) with a small component of aragonite needles in the upper section. This lies within lithostratigraphic Unit I (0-125.95 mbsf; Eberli, Swart, Malone, et al., 1997). The interruption of this unit by a possible hardground (a chalky layer) and a series of silty clay layers allows division of Unit I into two subunits. The upper interval (0-7.28 mbsf) is a nannofossil ooze with small amounts of aragonite needles, where particle abundance and grain size increases downcore to the base of this subunit. It is thought to reflect a mix of pelagic and bank-derived carbonates (Eberli, Swart, Malone, et al., 1997). The lower interval (7.28-125.95 mbsf) is a nannofossil ooze interbedded with clays reflecting erosion from a continental source, probably Cuba and/or Hispaniola (Eberli, Swart, Malone, et al., 1997).