Drilling occurred in the area of the IAP during four previous DSDP and ODP legs: DSDP Legs 13 and 47B and ODP Legs 103 and 149 (Fig. F1). The DSDP Leg 13 crew drilled one site on the southernmost edge of the IAP (Site 120) but recovered only six partial cores that contained sediments ranging in age from Late Jurassic to Early Cretaceous (Ryan, Hsü, et al., 1973). The crew of DSDP Leg 47B, however, recovered sediments that range in age from Barremian to Holocene at Site 398. This site also included a nearly complete section from the upper Campanian through the Paleocene (Fig. F3) (Sibuet, Ryan, et al., 1979).
ODP Leg 103 occupied five sites in an east-west transect on the western margin of the Galicia Bank to the north of the study area (Boillot, Winterer, Meyer, et al., 1987). Three of the sites (637, 638, and 639) contain middle to upper Miocene to Holocene sediments that rest unconformably on Lower Cretaceous sediments. Site 640 contains 150 m of barren clays resting on top of Aptian sediments. Site 641 contains Upper Cretaceous to Pleistocene sediments. As a result of poor recovery, only a few stringers of nannofossil-bearing upper Campanian to lower Maastrichtian marl were recovered (Boillot, Winterer, Meyer, et al., 1987).
ODP Leg 149 drilled five sites in an east-west transect on the eastern margin of the Iberia Abyssal Plain. Of these sites, at only one, Site 900, did we penetrate Paleocene sediments. A little more than 2 m of uppermost Paleocene sediments was recovered. These sediments fall within nannofossil Zone CP8 (Sawyer, Whitmarsh, Klaus, et al., 1994, p. 227), which represents only the last 1 m.y. of the Paleocene. At three sites, Sites 897, 898, and 899, we recovered Holocene to middle Eocene, upper Eocene, and Oligocene sediments, respectively. From Site 901 we recovered only Jurassic sediments (Sawyer, Whitmarsh, Klaus, et al., 1994).
Previous works on calcareous nannofossils from Upper Cretaceous to Paleocene sediments in the area have been published by Perch-Nielsen (1971a, 1971b) and Blechschmidt (1979). Blechschmidt reported on a nearly complete Upper Cretaceous to Paleocene section from Hole 398D (DSDP Leg 47B). Most nannofossils contained within these sections were moderately well to poorly preserved. There were some sections that were barren of nannofossils, but there were no indicated hiatuses.
Perch-Nielsen (1971a, 1971b) described many new upper Paleocene taxa from ODP Leg 12, Site 119, in the Bay of Biscay. The Bay of Biscay is northeast of the study area and is bordered by the northern margin of Spain and the western margin of France. Many of the fasciculithids, one sphenolithid, two heliolithids, and one Toweius recorded here were originally described from Site 119.
Calcareous nannofossils have been previously reported from Leg 173 in the Initial Reports volume (Whitmarsh, Beslier, Wallace, et al., 1998). There were no planktonic foraminifers reported from the sediments recovered. The shipboard work included a reconnaissance study of the nannofossils, mostly from core-catcher samples (every 9 m), and produced sedimentation rates based upon those findings. The present study, however, reports a much higher resolution of at least one sample per core section (at least one every 150 cm).