Figure 1. Antarctica and surrounding continents at the Cretaceous/Tertiary boundary, in early Oligocene and earliest Miocene times, showing the change from meridional to circum-Antarctic Current circulation that brought about the thermal isolation of Antarctica (Kennett, 1978).

Figure 2. Global sea level, tectonism, and ice volume (after Barrett, 1994). Left curve from Atlantic benthic foraminifers (Miller et al., 1987); right curve from seismic sequence analysis (Haq et al., 1987).

Figure 3. Trajectory of the South Tasman Rise with respect to Antarctica (J.-Y. Royer, unpubl. data). Because Antarctica has remained stable relative to the South Pole since the Cretaceous (e.g., Muller et al. 1993; DiVenere et al., 1994), it also shows the paleolatitudes of the STR. The close correspondence between the hot spot trace (dashed line) and the trace with Antarctica fixed (solid line) adds confidence to the interpretation (ages after Cande and Kent [1995] magnetic reversal time scale; magnetic chrons in parentheses).

Figure 4. Bathymetry of the offshore Tasmanian region, making use of Tasmante swath bathymetry. Solid lines = seismic profiles shown in Figure 5. Contours in meters.

Figure 5. Cross-sections from seismic profiles across the region showing DSDP and proposed high-priority ODP sites. P1 = west Tasmania, P2 and 3 = South Tasman Rise, P4 = East Tasman Plateau. Site locations are shown in Figure 4.

Figure 6. Map of the offshore Tasmanian region showing location of multichannel seismic tracks. Locations of DSDP sites and proposed ODP sites are also shown.

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