Bulk sediment parameters (CaCO3, TOC, and >63 µm) are reported in Tables T1, T2, T3, T4, T5, and T6. The results of the coarse-fraction analysis at Site 1095 are given in Table T7. All data are plotted vs. age. The age-depth models used for calculating linear sedimentation rates are based on the paleomagnetic stratigraphy presented by Barker, Camerlenghi, Acton, et al. (1999).
At this site, CaCO3 contents are generally low (Fig. F1); average values are <2 wt%. Four samples have higher values of up to 40 wt% from the upper Miocene sequence, whereas in the Pliocene and Quaternary sequence, only three samples have higher values between 3 and 7 wt%. The TOC average is ~0.3 wt% for the late Miocene and decreases upward to a value of 0.2 wt% in the Pliocene and Quaternary. Peak values of up to 1.0 wt% are restricted to single samples from the Pliocene and Quaternary. The >63-µm fraction shows significant peak values between 10 and 40 wt% in the upper Miocene. During the Pliocene, a large peak (~50 wt%) in the >63-µm fraction occurs ~4.9 Ma. Large peaks (between 10 and 40 wt%) can also be seen at 3.2 and 0.7 Ma. A general increase in weight percent of the coarse fraction (>63 µm) is characteristic for the past 3.2 Ma.
The contents of CaCO3 are very low (average = 1.5 wt%) throughout Site 1096 (Fig. F2), with only three peaks (up to 40 wt%) in the Pliocene, whereas several maxima are documented in the Quaternary, where the CaCO3 exceeds values of >30 wt%. The TOC shows average values of 0.25 wt%. During the Pliocene, one peak (7 wt%) occurred ~4.8 Ma, and during the Quaternary, three maxima (>1.0 wt%) took place between 1.7 to 1.0 Ma. The weight percent of the >63-µm fraction increased uphole from ~2.8 Ma to present. There are several peaks that exceed values of up to 30 wt%.
The CaCO3 shows larger and more frequent peaks with respect to Sites 1095 and 1096 (Fig. F3). The average values exceed 2 wt%. In the Pliocene, one maximum occurs ~2.1 Ma (values >40 wt%), whereas during the Quaternary (between 1.8 to 0.77 Ma), the CaCO3 peak values (between 10 to 30 wt%) seem to have occurred regularly every 2 and 0.5 m.y. TOC contents average 0.2 wt% at this site. The coarse fraction (>63 µm) was generally low during the Pliocene except for a peak of up to 15 wt% ~2.7 Ma. The coarse fraction increases uphole with a trend similar to the CaCO3 and is highly variable in the samples with ages between 1.6 and 0.78 Ma.
Significant differences in biogenic components (Fig. F4) occur within the 125- to 500-µm fraction. High amounts of biosiliceous particles, such as radiolarians and diatoms, characterize the Pliocene interval (4.5 to 3.2 Ma). Planktonic and benthic foraminifers (calcareous) occur within single samples that date to ~2.25 and 1.0 Ma, whereas the samples from ~3.3 Ma show greater numbers of agglutinated benthic foraminifers. The terrigenous particle input (Fig. F5) also documents significant changes in the composition of the particle assemblage. Angular quartz is present throughout the interval investigated. Greater numbers of the rounded quartz are present in samples dated between 4.2 and 0.8 Ma, with maxima ~3.2, 2.5, and 2.2 Ma. Feldspar is lower in samples with ages between 2.2 and 1.0 Ma. Mica is also variable. Biotite has two maxima, from 3.2 to 2.6 Ma and from 0.8 to 0.2 Ma. Higher contents of muscovite are found in samples from 4.4 to 4.1 Ma and from 0.8 to 0.2 Ma. Some igneous rock fragments (up to 4 grain%) were found mainly in samples with ages between 4.4 and 2.4, 2.1 to 1.6, and 0.8 Ma to present. Variations in the contents of metamorphic rock fragments are not well pronounced. It appears that in samples from 4.4 to 3.1 Ma and from 2.6 to 2.0 Ma, the amounts of this component are somewhat lower. Contents of sedimentary rock fragments are enhanced in samples with ages between 4.4 and 3.1 Ma as well as between 2.6 and 1.3 Ma, showing clear fluctuations in these two intervals. Volcanic glass and pyrite never exceed values of >20 grain%.
In summary, there are clear differences in both the bulk sediment parameters and in coarse-fraction composition through depth and time. CaCO3 content of the sediment varies between the three site locations on the continental rise. At Site 1095, CaCO3 contents were low during the Miocene. It appears that, in general, the CaCO3 content decreases from the northeast (Site 1101) to the southwest (Site 1095) during the Pliocene and the Quaternary. The >63-µm fraction provides evidence that sedimentation on the continental rise was always influenced by a certain degree of ice rafting, which has varied through time since the Miocene. For the time interval of the Pliocene and Quaternary, where a record from all three sites is available, there is a significant positive correlation between the three sites with respect to the timing and occurrence of peaks in the >63-µm fraction. In the future, additional studies need to be done to integrate these data sets in proposed sedimentation models for the rise area (e.g. Rebesco et al., 1998; Pudsey and Camerlenghi, 1998).