Site 1134 is located on the Eyre Terrace upper slope in 701.0 m of water (Fig. F1). This site was designed to intersect Cenozoic seismic Sequences 2, 3, and 4 and Lobes 2 and 3 of Sequence 6A (Feary and James, 1998, reprinted as Chap. 2; Fig. F2) and to intersect as much of the upper part of the Cretaceous section as time permitted. The target depth at this site was just below a high-amplitude reflector of probable Cenomanian age, estimated before drilling (on the basis of stacking velocities) to be at 520 meters below seafloor (mbsf).
The principal objectives at this site were to collect a detailed record of Paleogene-lower Neogene temperate to subtropical midlatitude sedimentation in an upper slope environment, and to recover a record of marine flooding of the evolving rift basin in the Cenomanian. Seismic interpretation (Feary and James, 1998, reprinted as Chap. 2) indicated that the lowermost Cenozoic sequence at this site (Sequence 6A) should be broadly contemporaneous with the Eocene?-middle? Mio-cene carbonate platform exposed on land and underlying the modern mid-inner shelf. Although seismic data show that a significant portion of this time interval (Sequence 6A, Lobe 1) is missing at this location, Site 1134 represents an ideal opportunity to sample the upper (Lobe 3) and the middle (Lobe 2) portions of this deep-water sequence, deposited apparently contemporaneous with this platform. Despite the absence of Lobe 1 at this location, it was likely that these deeper-water deposits should contain a more complete sequence than coeval shallow-water sediments, without lowstand hiatuses.
This site also constituted an upper slope component of the overall Leg 182 shelf-to-basin transect, designed to address a number of paleo-ceanographic problems: (1) the relationship between circulation patterns in the deep ocean and on the shelf during times of warm vs. cold oceanic conditions, (2) the precise timing and nature of the opening of the Tasman Gateway, (3) the evolution and effect of the Leeuwin Current, and (4) the relationship between primary productivity and cool-water carbonate development.
The relatively thin Cenozoic sequence at this location offered an opportunity to recover the uppermost part of the Mesozoic section, shown to be of Cenomanian age in the nearby Jerboa-1 exploration well. Although Jerboa-1 yielded a record of this interval in the form of ditch-cutting fragments, a fully cored section through this succession was sought to clarify facies relationships and the biostratigraphy of this near-shore marine interval.
The drilling objectives at Site 1134 were to
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Ms 182IR-112