Figure 1. Locations of Leg 177 drill sites and previous ODP and DSDP sites in the South Atlantic relative to major frontal boundaries.

Figure 2. Leg 177 sites relative to the vertical distribution of potential temperature on a transect from the Agulhas Ridge to Bouvet Island in the southeast Atlantic Ocean. NADW = North Atlantic Deep Water; CDW = Circumpolar Deep Water; AABW = Antarctic Bottom Water; AAIW = Antarctic Intermediate Water; SASW = Subantarctic Surface Water; SAF = Subantarctic Front; and PF = Polar Front.

Figure 3. Schematic representation of present ocean circulation and interocean exchange showing the central role of the circumpolar region in global circulation (numbers are flux in Sverdrups, 1 sv=106 m3/s). Not shown are the deep Indian and Pacific reservoirs (after Kier, 1988).

Figure 4. Schematic representation of the Southern Ocean showing its oceanic frontal system and sea-ice distribution relative to sites drilled by ODP and DSDP.

Figure 5. Position of Leg 177 sites relative to the gravity field of the Agulhas basin derived from Geosat ERM (Exact Repeat Mission) and GM data.

Figure 6. Schematic tectonic map of the Agulhas Basin showing Leg 177 sites relative to seafloor magnetic anomalies (after Raymond and LaBrecque, 1988). Contours are in meters

Figure 7. Tectonic reconstruction of the South Atlantic during the late Paleocene and middle Eocene with positions of sites drilled during Legs 114 and 177 (after Ciesielski, Kristoffersen, et al., 1988).

Figure 8. Temperature and salinity at water depths of Leg 177 sites taken from conductivity temperature-depth profiles collected during site-survey cruise TN057 aboard the Thomas G. Thompson. Temperature and salinity values are shown relative to components of North Atlantic Deep Water (NADW), which includes Labrador Sea Water (LSW), Gibbs Fracture Zone Water (GFZW), and DSOW (Denmark Straits Overflow Water). Also shown are mean values for Circumpolar Deep Water (CPDW).

Figure 9. Positions of Leg 177 sites relative to the depositional regimes in the basins around South Africa (after Tucholke and Embley [1984] and Ciesielski, Kristoffersen, et al. [1988]). 1 = core of circumbasin erosional zone; 2 = basement exposed by current erosion; 3 = sediment wave field; 4 = zone of thin sediment along the mid-oceanic ridge axis and beneath the ACC; 5 = thick sediment drifts with weak acoustic laminae; 6 = generalized bathymetric contours as labeled (4500 m is a dashed line); 7 = limit of thick, moderately laminated drifts of diatomaceous sediment extending north of the polar front; 8 = glide plane scars at the head of slumps and slides; 9 = approximate seaward limit of slumps and slides; 10 = seamounts; 11 = piston cores of pre-Quaternary outcrops (from left to right, top to bottom: Pliocene, Miocene, Oligocene, Eocene, Paleocene, and Cretaceous); 12 = manganese nodules/pavement observed in bottom photographs; 13 = current direction from bottom photographs; 14 = direct current measurements; and 15 = flow of AABW inferred from bottom-water potential temperature.

Figure 10. Downhole variations of percent blue reflectance (450-550 nm), volume-specific magnetic susceptibility, gamma-ray attenuation (GRA; line, smoothed data) and moisture and density (MAD; white dots) bulk density, and natural gamma radiation at Site 1094. Dashed lines indicate marine isotope stages inferred from peaks in blue reflectance which represent carbonate peaks.

Figure 11. Summary of lithologies and paleomagnetic stratigraphies of expanded sections recovered at Sites 1089 (41°S), 1091 (47°S), 1093 (50°S) and 1094 (53°S) along a north-south transect across the ACC; w.d. = water depth. The geomagnetic polarity time scale of Cande and Kent (1992) is shown on the right.

Figure 12. Age-depth plots for Leg 177 sites for the Pliocene-Pleistocene.

Figure 13. Age-depth plots for Leg 177 Sites 1088, 1090, and 1092 for the middle Eocene-Pleistocene. At Site 1088, the length of the dashed lines indicating hiatuses are not representative of the length of time involved. To make them visible on the figure, the dashed lines were extended across the depth/time line.

Figure 14. Summary of lithologies for Leg 177 Sites 1088 through 1094; w.d. = water depth.

Figure 15. Example of a laminated diatom mat from interval 177-1093A-23H-4, 78-108.5 cm.

Figure 16. Correlation of %red reflectance (650-750 nm) during the Brunhes Chron in expanded sections from Sites 1089 (41°S), 1091 (47°S), 1093 (50°S), and 1094 (53°S) along a north-south transect across the ACC. Dashed lines indicate marine isotope stages inferred from peaks in blue reflectance which represent carbonate peaks. B/M = Brunhes/Matuyama boundary.

Figure 17. Percent blue and red reflectance at Site 1090.

Figure 18. Pore-water profiles of chloride, sulfate, phosphate, and manganese from the high sedimentation-rate diatomaceous-ooze Sites 1091, 1093, and 1094. See text and individual site chapters for a more detailed explanation of the profiles.

Figure 19. Variation in oxygen-isotope ratio of deep-sea benthic foraminifers from the Atlantic Ocean (left) relative to the global sea-level curve inferred from seismic stratigraphic analysis (middle) (after Barrett, 1994). Shown on the right are Leg 177 sequences recovered over these time intervals.

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