Approximately 1.47 m (Sections 192-1187A-2R-1 and 2R-2) of upper Aptian to (possibly) Albian chalk and claystone was recovered above basalt basement encountered in Section 2R-2 in Hole 1187A. A summary of the biostratigraphic indices identified in the rotary-cored portion of Hole 1187A is presented in Table T3.
In addition, the 1 m of limestone and pelagic ooze obtained from the wash core (Core 192-1187A-1W) was analyzed for foraminifers in order to better incorporate Site 1187 into a regional paleoceanographic model (see "Lithostratigraphy" in the "Site 1183" chapter). Core 1W contains Oligocene pelagic ooze overlying middle to upper Eocene limestone.
The sediment recovered from the wash core (192-1187A-1W) was not examined for calcareous nannofossils.
Poorly preserved calcareous nannofossils are abundant in the white chalk (Sample 192-1187A-2R-2, 29 cm) directly above basement. The presence of Eprolithus floralis and Hayesites irregularis date this sample as late Aptian to late Albian; however, the absence of the Albian nannofossil taxa observed in mid-Cretaceous sections of cores recovered from Holes 1183A and 1186A favors a late Aptian age. The first occurrence of Eprolithus floralis also provided control on basal sediment ages at Sites 1183 and 1186.
Very rare and poorly preserved specimens of Watznaueria barnesae, which ranges throughout the Cretaceous, were recovered from two of eight samples taken from the brown claystone (see "Lithostratigraphy").
The upper portion of the sediment recovered in the wash core (Samples 192-1187A-1W, 4-9 cm, and 14-17 cm) is lower upper Oligocene ooze assigned to planktonic foraminifer Zone P21. An underlying limestone interval (Samples 192-1187A-1W, 94-96 cm, through 110-112 cm) was deposited below the foraminifer lysocline and is nearly barren of planktonic foraminifers. However, benthic foraminifers indicate a section comparable to the middle to upper Eocene section cored in Hole 1185 (Cores 192-1185A-2R through 8R). This correlation is further supported by a change in species composition that defines a global turnover in middle Eocene deep-water benthic foraminifers (see "Biostratigraphy" in the "Site 1185" chapter). In addition, the occurrence of rare specimens of the dissolution-resistant planktonic foraminifer species Globigerina senni confirms a middle Eocene age for Sample 192-1187A-1W, 110-112 cm.
Late Aptian planktonic foraminifers were recovered from both the brown claystone (interval 192-1187A-2R-1 to 2R-2) and the thin, white chalk (interval 2R-2, 28-30 cm) overlying basement (Table T3). Highly corroded specimens of Globigerinelloides aptiensis, which has been reported from the upper Aptian to middle Albian (Leckie, 1984), were recovered from the brown claystone (see "Lithostratigraphy"). A questionable specimen of the Albian taxon Blefuscuiana albiana was recovered from Sample 192-1187A-2R-1, 90-92 cm.
Benthic foraminifers are common and moderately well preserved in the chalk immediately above basement (Sample 192-1187A-2R, 28-30 cm). This assemblage is dominated by Gyroidinoides crassa, Gavelinella complanata, and Dorothia zedlerae, which are indicative of the transition from upper to lower slope environments (Moullade, 1984).
Washed residues of the dark brown claystone (Sections 192-1187A-2R-1 and 2R-2) are composed almost entirely of abundant fish-bone debris and very small ferromanganese nodules. This composition is consistent with very slow deposition of clay in a lower slope to abyssal setting and indicates that the CCD rose above Site 1187 shortly after deposition of the upper Aptian limestone. Washed residues from relatively rare orange-brown claystone intervals (Sample 192-1187A-2R-1, 90-92 cm) differ by having much less ferromanganese nodule material and by yielding very rare, noncalcareous agglutinated benthic foraminifers (mainly species of Ammodiscus and Glomospira). Fish-bone debris remains dominant, however. Only in mottled claystone of the upper part of the section (Sample 192-1187A-2R, 17-20 cm) does the amount of fish-bone debris decrease.
The sediment recovered in Core 192-1187A-1W tentatively indicates that the CCD did not again drop below Site 1187 until middle Eocene time. However, calcareous sediment between the Eocene limestone and Albian-Aptian claystone was not recovered.