Geological Framework of the Southern Lord Howe Rise/West Norfolk Ridge Region: Cruise Proposal

The Lord Howe Rise region is an enormous area of complex seabed lying 500-1500 km east of
Australia. It includes relatively shallow water features such as the Lord Howe Rise, and the
Norfolk, West Norfolk and Dampier Ridges, and intervening deeper water areas such as the LordHowe, Middleton and New Caledonia Basins. Based upon the UN Law of the Sea Convention,
Australia has a large seabed claim in this region because of Lord Howe, Norfolk and PhilipIslands, which are Australian territory and would all generate 200 nautical mile Exclusive
Economic Zones and related 'legal' Continental Shelf areas. There is a negotiated seabed boundaryin the north separating French and Australian territory, but as yet there is no negotiated seabed
boundary separating New Zealand and Australian territory in the south.

Owing to its vast size, many features within the Lord Howe Rise region remain sparsely covered
by seismic data. Analysis of available data has defined several areas that may have long-termpetroleum potential. The most significant of these are the rift system beneath the western Lord
Howe Rise, the New Caledonia basin and the Taranui Sea Valley area of the southern NorfolkRidge.

The Australian Geological Survey Organisation (AGSO - formerly the Bureau of MineralResources, BMR) Project 121.30 (Lord Howe Rise and Norfolk Ridge 'Law of Sea' Study) seeks
to improve our understanding of the geological framework of the southern part of the Lord HoweRise region in the vicinity of the Australia/New Zealand seabed boundary zone. Its major
objectives are:
1) To investigate the structure, stratigraphy and basin development of the southern Lord Howe
Rise, southern New Caledonia Basin, and West Norfolk Ridge in the Australia/New Zealandseabed boundary zone.

2) To assess the resource potential of the major structural features within the region.

3) To determine the tectonic framework, crustal characteristics and evolution of the region, andattempt to understand the processes that have produced narrow strips of thinned and extended
continental lithosphere ("ribbon continents"), separated by narrow ocean basins.
4) To acquire data to assist with the definition of Australia's 'legal' Continental Shelf on thesouthwestern margin of Lord Howe Rise.

To address these objectives it is proposed that RV Rig Seismic be used to acquire approximately 3250 km of multichannel seismic and associated geophysical data, and conduct dredging
operations, during a cruise in the southern Lord Howe Rise/West Norfolk Ridge region (Survey114). The seismic data will be recorded on eight lines (including four very long regional lines)
using a 3000 m streamer (120 x 25 m groups), 49 litre sleeve gun arrays, 16 second records, and
30-fold coverage.