Capel and Faust Basins - New Information from the Offshore Frontier Between Australia, New Zealand and New Caledonia

Brief description

New geophysical and geological datasets have been acquired in water depths of 1300-2500m from the Capel and Faust basins located some 800 km east of Brisbane (Figure 1). Between December 2006 and January 2007 Geoscience Australia acquired ~6000 km of industry standard 2D seismic data using an 8 km solid streamer. The survey identified numerous depocentres, some up to 150 km in length and 40 km in width with up to 7 km of sediment fill. Initial interpretation has identified a potential pre-rift succession, three syn-rift phases (clastic/volcanic), and two post-rift carbonate packages. Episodes of post-rift igneous activity are also apparent. Possible correlations with the Capricorn, Great South and/or deepwater Taranaki basins are suggested.

In late 2007 the RV Tangaroa completed a marine reconnaissance survey of the Capel and Faust basins. Geophysical datasets acquired on this survey included gravity, magnetics, multibeam sonar, and sub-bottom profiler data. An accompanying seafloor sampling program acquired geological and biological samples from potential seepage sites and representative areas of the sea floor, to search for indications of active petroleum systems and to document marine biodiversity and habitats. These datasets are designed to better define the region's petroleum prospectivity and inform marine and environmental planning decisions.

The multibeam sonar revealed seafloor features that appear to reflect the underlying basin structure, such as fault-related slumps. The gravity and magnetic coverages are expected to significantly improve the delineation of depocentre boundaries. Seafloor sampling and camera footages provided information on the substrate composition and potential fluid escape sites. Current work involves the initial interpretation of these datasets and their integration to define the rift basin architecture and tectonostratigraphic history to better understand the region's petroleum prospectivity.

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