Site 1067 is situated near the northern edge of the southern Iberia Abyssal Plain at 40°40.95´N, 11°35.75´W, in 5020.90 m of water. Coring began at 648.00 meters below the seafloor (mbsf) at Hole 1067A and continued over the next 207.60 m; we recovered only 77.67 m of sediment (average recovery = 37.4%) to a total depth of 855.6 mbsf. We recovered sediments from Cores 173-1067A-1R through Section 14R-1 (648.00-763.08 mbsf). These sediments range from middle Eocene to latest Paleocene in age and consist of greenish gray calcareous claystones, calcareous silty claystones, and light gray calcareous siltstones and sandstones. Relative abundances of species and biostratigraphically identified units from Site 1067 are presented in Table T1.
Paleocene sediments were encountered at Sample 173-1067A-13R-1, 47-48 cm (754.67 mbsf), just below the first occurrence of Discoaster diastypus (see McGonigal and Wise, Chap. 4, this volume). Based on the occurrence of Discoaster multiradiatus, this section was assigned to Zone CP8. This zone was traced downhole to Sample 173-1067A-13R-2, 28-29 cm (755.98 mbsf), which is barren of nannofossils. This barren interval persisted downhole to Sample 173-1067A-14R-1, 0-3 cm (763.80 mbsf), where a rare occurrence of Coccolithus pelagicus indicates that the sediments are still Cenozoic in age; however, no other significant datums were encountered in this sample. This last sample represents the lowest occurrence of sediments that rest directly upon basement rock.
Site 1068 is situated near the southern edge of the IAP, at 40°40.955´N, 11°36.720´W, in 5043.90 m of water. Coring began at 711.30 mbsf in Hole 1068A and continued over the next 244.50 m, recovering only 180.59 m of sediment (average recovery = 73.9%), to a total depth of 955.80 mbsf. Sediments were recovered from Core 173-1068A-1R through Section 15R-5 (711.30-853.02 mbsf). These sediments range from middle Eocene to Maastrichtian in age and consist of claystones, calcareous claystones, nannofossil chalk, and calcareous siltstones. The Paleocene section is dominated by carbonate turbidites and upward-darkening sequences that contain a record of all Okada and Bukry (1980) zones (Table T2).
Paleocene sediments were encountered at Sample 173-1068A-8R-4, 44-45 cm (783.84 mbsf), based on the absence of D. diastypus (see McGonigal-Roessig and Wise, Chap. 4, this volume) and the presence of D. multiradiatus. The first occurrence (FO) of D. multiradiatus, which marks the lowest boundary of Subzone CP8a, was noted in Sample 173-1068A-9R-6, 28-29 cm (796.28 mbsf). Within Zone CP8 are occurrences of Fasciculithus shaubii, Fasciculithus lillianae, and single occurrences of many other fasciculithids (Plate P1). The FO of Discoaster nobilis was noted in Sample 173-1068A-10R-3, 123-125 cm (802.33 mbsf), which marks the bottom of Zone CP7.
The FO of Discoaster mohleri, which marks the lowest boundary of Zone CP6, is found in Sample 173-1068A-11R-3, 15-17 cm (810.85 mbsf). The occurrence of D. mohleri in Sample 173-1068A-11R-4, 35-36 cm (812.55 mbsf), is considered to be reworked because it was found in the same sample as the FO of Heliolithus kleinpellii. Within Zone CP6, in Sample 173-1068A-11R-2, 8-9 cm (809.28 mbsf), is the FO of Heliolithus riedelii. Discoaster bramlettei (Plate P2) was also noted within this section and persists to the bottom of Zone CP5. The FO of H. kleinpellii in Sample 173-1068A-11R-4, 35-36 cm (812.55 mbsf), marks the lower boundary of Zone CP5. The lower boundary of Zone CP4 is marked by Fasciculithus tympaniformis; its last observed occurrence is found in Sample 173-1068A-11R-CC, 3-4 cm (815.41 mbsf). Below this level is a long interval that is barren of calcareous nannofossils. This barren interval persists to Sample 173-1068A-12R-5, 35-36 cm (823.65 mbsf), in which F. tympaniformis is absent, placing the lower boundary of Zone CP4 in Sample 173-1068A-12R-4, 140-143 cm (823.20 mbsf).
The CP3 lower zonal boundary is marked by the FO of Ellipsolithus macellus, which was noted as a single occurrence in Sample 173-1068A-13R-2, 20-21 cm (828.60 mbsf). Zone CP2 and Subzone CP1b had to be combined because we could not distinguish Chiasmolithus danicus in any sample in this part of the column. The FO of Cruciplacolithus tenuis in Sample 173-1068A-13R-5, 78-79 cm (833.68 mbsf), marks the base of this combined zone. The Cretaceous/Tertiary (K/T) boundary was placed between Sample 173-1068A-13R-6, 52-53 cm (834.92 mbsf), and Sample 173-1068A-13R-6, 69-70 cm (835.09 mbsf), based on the lack of Cenozoic forms in the latter sample.
The interval from Sample 173-1068A-13R-6, 82-83 cm (835.22 mbsf), to Sample 173-1068A-15R-4, 10-11 cm (850.39 mbsf), is classified here as Subzone CC25c/Zone CC26 (Table T3), based on the FO of Micula murus. The sediments in this interval are dominated by Arkhangelskiella cymbiformis, Cribrosphaerella ehrenbergii, Micula decussata, Prediscosphaera cretacea, Retecapsa crenulata, and Watznaueria barnesae (Plate P3). The lack of Micula prinsii and reliable Nephrolithus frequens makes it impossible to resolve a more precise zonation. The interval from Sample 173-1068A-15R-4, 12-13 cm (850.41 mbsf), to Sample 173-1068A-15R-4, 101-102 cm (851.30 mbsf), is assumed to belong to Subzone CC25b; however, the absence of reliable datums makes it difficult to assign this section to any zone. The latter sample represents the lowest occurrence of Upper Cretaceous sediments at Site 1068.
Site 1069 is situated in the southern IAP, at 40°43.612´N, 11°46.633´W, in 5074.80 m of water. Coring began at 718.80 mbsf at Hole 1069A and continued over the next 240.50 m, recovering only 96.30 m of sediment (average recovery = 40.0%) to a total depth of 959.30 mbsf. Sediments were recovered from Core 173-1069A-1R through Section 17R-1 (718.80-873.70 mbsf). These sediments range from middle Eocene to Late Jurassic in age and consist of claystones, calcareous claystones to nannofossil claystones, nannofossil chalk, and calcareous siltstones. The upper Campanian to Paleocene section is dominated by carbonate turbidites and upward-darkening sequences.
Paleocene sediments were encountered at Sample 173-1069A-7R-5, 18-19 cm (782.98 mbsf), based on the absence of D. diastypus (see McGonigal and Wise, Chap. 4, this volume) and the presence of D. multiradiatus (Table T4). The FO of D. multiradiatus, which marks the lowest boundary of Zone CP8, is noted in Sample 173-1069A-7R-CC, 20-22 cm (784.58 mbsf). Within Zone CP8 are occurrences of F. shaubii, F. lillianae, and Fasciculithus alanii, as well as many other fasciculithids. The only occurrence of D. nobilis was noted in Sample 173-1069A-8R-1, 33-34 cm (786.73 mbsf), which marks the bottom of Zone CP7.
The FO of D. mohleri, found in Sample 173-1069A-8R-2, 70-71 cm (788.6 mbsf), marks the lower boundary of Zone CP6. Within this zone in Sample 173-1069A-8R-1, 87-90 cm (787.27 mbsf), is a single rare occurrence of H. riedelii; this sample also marks the lowest observed occurrence of H. kleinpellii. From Sample 173-1069A-8R-2, 117-118 cm (789.07 mbsf), to Sample 173-1069A-8R-5, 62-63 cm (793.02 mbsf), is a long barren interval, below which assigning a zonation to the samples becomes very difficult because of a lack of reliable markers and the presence of numerous barren intervals. The absence of H. kleinpellii and F. tympaniformis below this interval indicates that these samples belong to Zone CP3. The lower boundary of Zone CP3 is tentatively marked as the first common occurrence of Prinsius martinii in Sample 173-1069A-11R-1, 128-129 cm (816.58 mbsf). Perch-Nielsen (1979) showed that P. martinii could be used to approximate the lower boundary of Zone CP3, although it appears slightly lower than E. macellus.
A single occurrence of C. danicus and the last occurrence of a generic Chiasmolithus spp. mark the lower boundary of Zone CP2 in Sample 173-1069A-11R-3, 91-92 cm (819.21 mbsf), below which is the first common occurrence of Prinsius dimorphosus in Sample 173-1069A-11R-4, 79-81 cm (820.59 mbsf). Perch-Nielsen (1979) showed that P. dimorphosus falls within the middle of Subzone CP1b. The lower boundary of Subzone CP1b is marked here by C. tenuis in Sample 173-1069A-12R-1, 1-2 cm (825.01 mbsf).
The K/T boundary was found between Sample 173-1069A-12R-1, 113-114 cm (826.13 mbsf), and Sample 173-1069A-12R-1, 120-122 cm (826.20 mbsf). The absence of Cenozoic forms in the latter and the presence of Bianolithus sparsus in Sample 173-1069A-12R-1, 62-64 cm (825.62 mbsf), make it possible to place the boundary here despite the fact that Sample 12R-1, 113-114 cm (826.13 mbsf), is barren.
Upper Cretaceous nannofossils indicate a fairly continuous section from the upper Campanian to the end of the Cretaceous; however, the lack of certain key markers made the combination of some zones necessary (Table T5). Most of the combined zones occur in the Maastrichtian and could be the result of hiatuses or poor preservation that results from deposition at or below the carbonate compensation depth (CCD). Preservation throughout the Cretaceous is moderate to poor (Plate P4), and samples generally contain abundant nannofossils with the exception of a few short barren intervals.
The lower boundary of Subzone CC26b is located in Sample 173-1069A-12R-5, 135-137 cm (832.35 mbsf), and is marked by the FO of M. prinsii. Subzones CC25c and CC26a had to be combined here because of the absence of N. frequens. The FO of M. murus in Sample 173-1069A-14R-1, 77-79 cm (845.17 mbsf), marks the lower boundary of this combined zone. Zone CC24 through Subzone CC25b were combined as a result of the absence of Lithraphidites quadratus and Reinhardtites levis. The lower boundary of this combined zone is approximated here by the last common occurrence (LCO) of Uniplanarius trifidus in Sample 173-1069A-14-2, 16-18 cm (846.06 mbsf). There may possibly be hiatuses in this section that cannot be resolved by our zonation.
In the Campanian, all zones are present through Subzone CC22a. The lower boundary of Subzone CC23b is marked by the LCO Broinsonia parca constricta in Sample 173-1069A-15R-1, 138-141 cm (855.38 mbsf). There are two uphole occurrences of Broinsonia parca constricta that are considered here as reworked. The lower boundary of Subzone CC23a is marked by the LO of Eiffellithus eximius in Sample 173-1069A-15R-3, 19-21 cm (857.77 mbsf). The FO of U. trifidus marks the lower boundary of Zone CC22 and was found in the lowermost sample studied in this hole, Sample 173-1069A-16R-2, 38-41 cm (865.48 mbsf). The absence of reliable occurrences of R. levis and Lithastrinus grillii makes it impossible to distinguish subzones within Zone CC22.
Site 398 is situated on the southern flank of the Vigo Seamount, at 40°57.6´N, 10°43.1´W, in 3910 m of water. Continuous coring began at 489.5 mbsf (nine spot cores were taken over the first 489.5 m) in Hole 398D and continued over the next 1298.0 m, recovering only 936.6 m of sediment (average recovery = 72.2%), to a total depth of 1740.0 mbsf. Sediments were recovered from Cores 47B-398D-1R through 138R-2 (0.0 to 1740.0 mbsf). These sediments range from Holocene to Early Cretaceous in age and consist of claystones, calcareous claystones to nannofossil claystones, nannofossil chalk, and calcareous siltstones.
The Cretaceous nannofossil zonation performed by Blechschmidt (1979) was loosely based upon a zonation scheme proposed by Thierstein (1976) with her own modifications. The Cenozoic nannofossil zonation was loosely based upon Martini (1971). Samples were obtained near zonal boundaries in both the Cretaceous and Cenozoic sections for the purpose of updating the Blechschmidt zonal scheme to the zonal schemes used in this paper. The result of our review is shown in Figure F3, where Hole 398D is correlated with Holes 1069A and 1068A.
Nearly all Okada and Bukry (1980) biozone markers were present in the Cenozoic section of Hole 398D with the exception C. tenuis, which could not be recognized due to poor preservation. The lack of this marker made it necessary to combine Subzones CP1a and CP1b.
Poor preservation in the Cretaceous made it impossible to recognize many subzones. Zones CC26, CC23, and CC22 were not subdivided because of the lack of reliable datums. Zone CC24 and Subzone CC25a were combined because of the absence of R. levis. This part of the section may harbor hiatuses that cannot be resolved by our zonation.