The Lord Howe Rise (LHR) is a frontier area that extends from southwest of New Caledonia to the Challenger Plateau, west of New Zealand. It has a total area of about 1,500,000 km2. In general, the shallowest water lies in the east, although, a number of isolated islands and banks (including Lord Howe Island) make up the North-South trending Lord Howe Seamount Chain on the western flank. The LHR is underlain by continental crust that detached from eastern Australia during the margin breakup that led to the formation of the oceanic Tasman Basin from 85-52 Ma. The LHR is now separated from eastern Australia by the Tasman Basin and is bound to the east by the New Caledonia Basin.
The LHR comprises four sub-parallel geological provinces that extend for most of its length. From east to west, these provinces comprise shallow, planated, probable Palaeozoic basement of the Lord Howe Platform, overlain by a few hundred metres of mainly Cainozoic siliceous and carbonate oozes. To the east, the basement of the New Caledonia Basin is about 4 km deeper and of uncertain crustal affinity, while the western boundary of the platform is defined by a sharp Cretaceous hinge.
The central rift province, adjacent to the Lord Howe Platform, is characterised by a series of poorly defined basement blocks, normally down-faulted to the west, with 2-4 km of Upper Cretaceous and Cainozoic syn and post-rift section. This province includes the Faust Basin in the north and the Moore Basin in the south. The western rift province is separated from the central rift by a broad fault zone across which basement is down-faulted to the west. Basement and water depths are considerably deeper than in the central rift and the syn and post-rift sediments are considerably thicker. This province includes the Capel Basin in the north and the Monawai Basin in the south. In the vicinity of Lord Howe Island, the central and western rifts cannot be separated and the combined rift has been referred to as the Gower Basin. The western bounding complex ridge system, of a known continental origin, consists of the Dampier Ridge in the north and is separated from the western rift province by the Lord Howe and Middleton Basins, which may be underlain by highly extended lower continental crust. Further south, where extension is less extreme, the Monawai Ridge forms an intact outer margin to the Monawai Basin.
Knowledge of the LHR is relatively sparse and stems largely from seismic surveys conducted between the early 1970s and late 1990s. The Gower Basin is the only part of the LHR that is covered by a relatively systematic seismic grid, though the line spacing is still very regional in nature. The region has long been recognised as having long-term hydrocarbon potential as a frontier province. A recent interpretation of all the available regional data sets, shows that potentially prospective sedimentary basins underlie much of its western half and also its eastern flank adjacent to the New Caledonia Basin.