Publication Name: Eastern Australian Basins Symposium III (EABS 2008)
Authors: M.S. Norvick, R.P. Langford, T. Hashimoto, N. Rollet, K.L. Higgins and M. P. Morse
Date Published: September 2008
Number of Pages: 20
Abstract:
New seismic, gravity and magnetic data over the Capel and Faust basins have allowed improved resolution of the basin architecture and a better appreciation of the stratigraphy, terrane evolution and palaeogeography. Preliminary interpretation suggests that the Capel Basin contains several depocentres up to 150 km long and 40 km wide that contain up to four seconds two-way time (s TWT) sediment thickness. Graben stratigraphy appears to include Lower Cretaceous synrift volcanics, Turonian–Maastrichtian synrift clastic megasequences and a Maastrichtian–Recent postrift bathyal phase. There may also be a Lower-Middle Jurassic pre-rift sequence, possibly an equivalent of the Walloon Coal Measures in the Clarence-Moreton Basin. Total Jurassic-Recent sediment thickness may be as much as 6–7 km. A number of smaller graben characterise the Faust Basin to the east and the southern part of the Capel Basin. Stratigraphic complexity was driven by multiple extension events. Subsequent discrete seafloor spreading events resulted in the sequential formation of the Tasman Sea, and possibly the Middleton Basin, proto-Loyalty Basin, and central New Caledonia Basin. Plate reconstructions indicate that the Capel Basin was located adjacent to the northern edge of the Sydney Basin prior to breakup. The junction between the Capel and Faust basins is a major fault system, which may have exploited a Middle Triassic collision suture between the New England Orogen and equivalents of the Maitai–Murihiku terranes of New Zealand. The interpreted Lower Cretaceous volcanics are expected to correlate with the Lower Cretaceous igneous complexes and associated volcanogenic sediments in Queensland, Bass Strait and New Zealand. Sediment analogues of the mid-Cretaceous rift fill in the Capel–Faust area can possibly be found in the Gippsland and Great South basins, but exact correlations will be difficult because of the diachronous breakup of Tasman continental fragments/terranes. The Capel Basin, in particular, may contain sediments capable of generating gas and perhaps some liquids such as those seen in Clarence–Moreton and Great South basins.