Publication Name: Eastern Australian Basins Symposium 2001
Authors: J.B. Willcox, J. Sayers, H.M.J. Stagg and S. van de Beuque
Date Published: November 2001
Number of Pages: 38
Reference Type: Magazine Article
Abstract:
The Lord Howe Rise (LHR) region comprises a system of ridges, basins and seamount chains in the Tasman Sea. The LHR itself is a 'continental ribbon ', I ,600 km long and 400 - 500 km wide. Water depths are 1,000- 1,500 m along its crest, 3,000+ min the New Caledonia Basin to the east, and -5,000 min the Tasman Sea to the west. Regional structural elements trend N-S and NW-SE and include:? the Lord Howe Platform underlying eastern LHR;
? then westwards, a 'Central Rift Province' (Faust, Gower and Moore Basins);
? a 'Western Rift Province' (Capel, Gower and Monawai Basins);
? deep-water flanking basins (Lord Howe and Middleton) and ridges (Dampier and Monawai); and
? eastwards, the Fairway Basinfrrough and Ridge, and the New Caledonia Basin and Norfolk Ridge.
Widespread seismic tectono-stratigraphic sequences suggest little age difference between the basinal elements, though the eastern margin of LHR may be the oldest. Evolutionary stages comprise: pre-rift continental 'basement' ; two Early Cretaceous syn-rift (pre-Tasman Sea) phases (similar to the Bass Strait basins), separated by Cenomanian uplift/inversion; breakup/thermal subsidence from the Early Campanian (c. 83 Ma), with fully marine conditions established by the Maastrichtian; blanketing by marine ?terrigenous sediments following global plate reorganisation in the Middle Eocene (c. 42 Ma); and open marine pelagic sedimentation from the Oligocene when the Australian and Antarctic Plates fully separated (c. 35 Ma). From the Middle Eocene, compression along a new plate boundary to the east created W-E directed thrusting in the Norfolk Ridge/New Caledonia area, and folding/reverse faulting in the west.
Unresolved problems within the LHR region include:
? the age of the New Caledonia Basin,
? the crustal type beneath the New Caledonia, Lord Howe and Middleton Basins,
? the location of the Gondwanan margin,
? the nature of basement underlying the LHR syn-rift section, and
? structural controls.