Site 1133 was located in 1037.2 m of water on the middle-upper slope of the Great Australian Bight (Fig. F1) and was designed primarily to address Cenozoic paleoceanographic objectives. The site was also situated to provide intermediate depth information as part of the overall shallow-to-deep drilling transect across the margin.
Site 1133 was located to intersect an expanded Neogene section that primarily consists of a thick interval (>1100 m) mapped as seismic Sequence 4 (Feary and James, 1998, reprinted as Chap. 2), overlain by a thinner (>250 m) interval of Sequence 3 (Fig. F2). Although other sites targeted these sequences to some extent (e.g., Site 1130 intersected Sequence 3, and Site 1132 intersected both Sequences 3 and 4), Site 1133 presented an opportunity to obtain a much-expanded record through these sequences. However, the expanded nature of the section at this location also carried the risk that lower parts of the section would not be cored if drilling penetration rates became too low to achieve these targets within a reasonable time. An excessive target depth (1727 m) was deliberately chosen for this site so that it could act as a fallback location should poor weather or bad drilling conditions rule out many of the other sites. Another consideration for site location was the need for an intermediate water depth site to recover equivalent intervals to horizons at the deepest water site (Site 1128) anticipated to lack calcareous fauna as a consequence of carbonate compensation depth (CCD) fluctuations.
A submarine canyon system occurs to the west of Site 1133 (Fig. F1), consisting of a broad canyon on the lower slope and narrow 'tributary' channels extending onto the upper slope. This system complicates seismic ties between this site and the other Leg 182 drill sites to the west and makes detailed seismic sequence assignment difficult. Nevertheless, sequence correlations were expected to be broadly correct, with the succession expected to consist of a thin Pleistocene interval (<100 m), corresponding to seismic Sequence 2; an intermediate thickness (~260 m) of Sequence 3, expected to be of Pliocene age; and the considerably expanded Miocene section (>1100 m) of Sequence 4. In each case, the components of this succession were expected to provide deeper water facies information for comparison with shallower water equivalents at other sites. Despite approval for drilling through to the Paleogene (Sequence 7) and Cretaceous, there was no realistic expectation that these targets could be reached.
The broad objectives for Site 1133 were to
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