The sediments drilled at Site 1087 exhibited only a few minor gas expansion cracks. No flow-in was observed. Core disturbance is minimal. Material cored with the extended core barrel below Core-175-1087C-28X consisted of drilling biscuits embedded in drill mud. Sediments from Site 1087 form two lithostratigraphic units composed of nannofossil ooze with varying abundances of clay and foraminifers (Fig. 1). The sediments recovered from Site 1087 are lithologically similar to sediments from Sites 1086 and 1085.
Unit I is composed of light gray (5Y 7/1), pale olive (5Y 6/3) and light olive-gray (5Y 6/2) foraminifer-nannofossil ooze, foraminifer-rich nannofossil ooze, foraminifer-bearing nannofossil ooze, and nannofossil ooze. Sandy nannofossil-foraminifer ooze is present in 50- to 100-cm-thick beds in the upper 45 m of Holes 1087A, 1087B, and 1087C. These beds generally have sharp bases and grade upward from foraminifer sands into more clay-rich, olive-colored foraminifer-nannofossil ooze. The tops of these layers are often intensely bioturbated. These beds are interpreted as turbidites or the products of winnowing. All cores are moderately bioturbated, and burrows range in diameter from 1 mm to over 1 cm.
Some larger burrows are dark gray, contain abundant pyrite, and are frequently filled with silt- to sand-sized foraminifer tests. Gray blebs with abundant pyrite are found disseminated throughout Cores 175-1087C-32X through 38X. Cores 40X, 41X, and 43X contain pyrite nodules ranging in diameter from 1 mm to 2 cm. Occasionally, Zoophycos traces are identified. Intervals of different colored sediment range in thickness from 40 to 100 cm and grade into one another over 15 to 20 cm. Small, finely dispersed fine sand-sized pyrite grains are ubiquitous below Core 175-1086A-16H. The boundary between Units I and II occurs between Cores 175-1087C-46X and 47X. Across the boundary, light greenish gray (5GY 7/1) nannofossil ooze changes to foraminifer-bearing nannofossil ooze that exhibits rapid changes in color, high abundances of pyrite in darker colored sections, and microfaulted thinly laminated sections. This lithostratigraphic contact coincides with the disconformity identified from biostratigraphy ("Biostratigraphy and Sedimentation Rates" section, this chapter).
Unit II extends from Cores 175-1087C-47X to the bottom of the hole at 53X. It is composed of 2- to 100-cm-thick, light gray (5Y 7/2) greenish gray (5G 6/1), light olive-gray (5Y 5/1), light greenish gray (5G 7/1), brown (10YR 4/3), and brownish gray (10YR 6/1) intervals of foraminifer-bearing and foraminifer-rich nannofossil ooze. These intervals have bioturbated boundaries that grade over 2–10 cm (see Fig. 2). Intervals of thinly laminated sediments are common and often convolutely layered, microfaulted, and sometimes tightly folded. Contacts between intervals are sharp. Individual laminae have sharp upper and lower contacts and range in thickness from 1 to 3 mm. The top of Core 175-1087C-50X contains a large pyrite concretion surrounded by a 1-cm-thick brown (10YR 4/3) iron oxide–rich rim of foraminifer-bearing nannofossil ooze (see Fig. 3). The oxidized rim is interpreted as a secondary feature resulting from reoxidation of the outside of the pyrite nodule. Because the pyrite nodule must have grown under reducing conditions below the surface, it must have been exposed via oxygenated conditions later. Biostratigraphy indicates that there is a large disconformity between Cores 175-1087C-49X and 50X ("Biostratigraphy and Sedimentation Rates" section, this chapter), supporting the interpretation of an erosional contact near the stratigraphic level of the pyrite nodule. Below the erosional contact are fine laminae that are mircofolded with sharp upper and lower contacts (see Fig. 4). Cores 175-1087C-51X through 53X are composed of moderately bioturbated 10-cm-thick layers of light gray (5Y 7/2, N/8) carbonate-rich nannofossil oozes and light brownish gray (10YR 6/3) foraminifer-bearing nannofossil oozes. The contacts between these intervals are bioturbated and grade into one another over 2 cm.
The detrital component in sediments from Site 1087 is dominated by clay and trace abundances of silt-sized, subangular mono- and polycrystalline quartz grains. Authigenic minerals are rare or present in trace abundances. Pyrite is present as silt-sized aggregates of euhedral crystals or as framboids. Very fine-grained phosphate peloids are present in bioturbated beds in trace to few amounts in Cores 175-1087A-18H, 20H, 22H, and 25H. In Unit II, iron oxide minerals may be responsible for the brownish color, whereas apatites may be responsible for the yellowish color exhibited by the sediments. The biogenic component of both units consists of abundant to very abundant nannofossils. Foraminifers are abundant to few. The abundance of diatoms is few in Cores 175-1087A-8H and 10H. Siliceous spicules, dinoflagellate cysts, and radiolarian tests are present in trace amounts.
Color reflectance data were measured every 4 cm for Holes 1087A, 1087B, 1087C, and 1087D (Fig. 5, Fig. 6). The total reflectance values range between 45% and 70% (Fig. 2, Fig. 3), reflecting the high average calcium carbonate contents at this site. The downcore variation in the total reflectance values shows high variability attributed in part to intervals of light coarse-grained foraminifer beds in the upper 50 mbsf (Fig. 2, Fig. 5) and to a low sedimentation rate (see "Biostratigraphy and Sedimentation Rates" section, this chapter). Total reflectance and the red/blue wavelength ratio at Hole 1087C display distinct features (see Fig. 6): There are high values of total reflectance between 100 and 120 mbsf and between 270 and 330 mbsf and pronounced low total reflectance values in the interval between 340 and 370 mbsf. Similar variations have been observed at Site 1085 (see "Lithostratigraphy" section, "Site 1085" chapter, this volume). The red/blue ratio shows high values between 450 and the bottom of the core. These high values are thought to be associated to the presence of iron oxides in the sediments (see above).