(Table 1) Planktonic foraminiferal datum events of ODP Leg 166 sites

Planktonic foraminifers recovered from Leg 166 drilling showed a progression from well-preserved to poorly preserved specimens with increasing depth. The high carbonate production and shedding from the Great Bahama Bank diluted the pelagic components to the extent that planktonic foraminifers had scattered occurrences, particularly in the lower Pliocene and/or uppermost Miocene sections in Sites 1003-1005 and Site 1007. A reasonable planktonic foraminiferal biostratigraphic framework was possible for these sites because samples from thin, clay-rich layers contained moderately to well-preserved specimens throughout the lower Pliocene to Miocene interval. Better preservation of the specimens occurred in these layers because they were dominated by terrigenous sedimentation.
The planktonic foraminiferal zonation shows that Neogene sediments with a basal age of earliest Miocene were recovered from Holes 1003A-1003C. Four unconformities were identified on the basis of planktonic foraminiferal taxa. Upper Pliocene to Holocene sediments were recovered from Hole 1004. Sediment diagenesis prevented placement of the Pliocene/Pleistocene boundary. Middle Miocene to Pleistocene sediments were recovered from Holes 1005A-1005C. A large unconformity separates the lowermost upper Miocene and lower Pliocene sediments. At Site 1006, a complete middle Miocene to Pleistocene section was recovered, in contrast to the sites more proximal to the Bahamian platform. The lower Pliocene recorded high sedimentation rates. Holes 1007A-1007C recovered Neogene and uppermost Oligocene sediments. Three prominent unconformities were identified at the Pliocene/Pleistocene boundary, upper/lower Pliocene boundary and the Miocene/Pliocene boundary. The lower upper Miocene to uppermost Oligocene section appears to be complete at this site.

从第166航次钻探（Leg 166 drilling）中回收的浮游有孔虫（planktonic foraminifers）显示，随着深度增加，标本的保存状态由完好逐渐变差。大巴哈马滩（Great Bahama Bank）的高碳酸盐生产作用及沉积物剥蚀搬运稀释了远洋组分（pelagic components），导致浮游有孔虫呈零星分布，尤其在1003-1005站位及1007站位的下上新统（lower Pliocene）和/或上中新统最顶部（uppermost Miocene）地层中。
尽管如此，上述站位仍可建立合理的浮游有孔虫生物地层框架（biostratigraphic framework），因为薄而富黏土层（clay-rich layers）的样品在整个下上新统至中新统层位中均保存有中等至完好的标本。这些层位的标本保存更佳，因为它们以陆源沉积作用（terrigenous sedimentation）为主。

浮游有孔虫生物地层分带（planktonic foraminiferal zonation）结果显示，1003A-1003C钻孔采获了底界年龄为早中新世最早期的新近纪沉积物。基于浮游有孔虫类群，共识别出4处不整合面（unconformities）。1004钻孔采获了上新统上部至全新统（Upper Pliocene to Holocene）沉积物。沉积物成岩作用（sediment diagenesis）阻碍了上新统/更新统界线（Pliocene/Pleistocene boundary）的准确厘定。1005A-1005C钻孔采获了中中新统至更新统沉积物。一处大型不整合面分隔了上中新统底部与下上新统沉积物。

在1006站位，相较于更靠近巴哈马台地的其他站位，本次钻探恢复了完整的中中新统至更新统地层。该区域下上新统记录了高沉积速率。1007A-1007C钻孔采获了新近纪及渐新统最顶部地层的沉积物。该站位共识别出3处显著不整合面，分别对应上新统/更新统界线、上新统上下部界线以及中新统/上新统界线。该站位的上中新统下部至渐新统最顶部地层整体保存完整。