Lord Howe Rise

Last updated
Lord Howe Rise
Stratigraphic range: 216–6.5  Ma
Zealandia, topographic map.jpg
The Lord Howe Rise is part of the continent known as Zealandia.
Location
Coordinates 28°S161°E / 28°S 161°E / -28; 161
Region South Pacific, Coral Sea, Tasman Sea
Type section
Named for Lord Howe Island


The Lord Howe Rise is a deep sea plateau which extends from south west of New Caledonia to the Challenger Plateau, west of New Zealand in the south west of the Pacific Ocean. To its west is the Tasman Basin and to the east is the New Caledonia Basin. [1] Lord Howe Rise has a total area of about 1,500,000 km2 (580,000 sq mi), [1] and generally lies about 750 to 1,200 metres under water. [2] It is part of Zealandia, a much larger continent that is now mostly submerged, and so is composed of continental crust. Some have included the 3,500 m (11,500 ft) deep New Caledonia Basin as within the rise, given its continental crust origin, and this would give a larger total area of 1,950,000 km2 (750,000 sq mi). [3]

Contents

Geology

The Lord Howe Rise is associated with seafloor spreading which also resulted in the creation of the Tasman Sea. [4] The geology has not yet been characterised as well as other parts of Zealandia but when previous samples are analysed with current geological techniques they fit with the Zealandia hypothesis. [5] The seafloor is known to be dominated by soft sediments and the highest quality recent survey only mapped approximately 25,500 km2 (9,800 sq mi) of the western flank of the rise which is less than 1% of the total area of the rise. [3] In this area about 0.1% of the rises seafloor was classed as hard substrata based on a combined area of 31 km2 (12 sq mi) for 16 volcanic peaks. [3] Sandstone rocks dredged from the central Lord Howe Rise contained granite pebbles that were in the range 216–183 million years old. [6] It was rifted away from Eastern Australia in association with a mid-ocean ridge that was active from 80 to 60 million years ago, and now lies 800 kilometres offshore from mainland Australia.

The Lord Howe Rise contains a line of seamounts called the Lord Howe Seamount Chain which formed during the Miocene period when this part of Zealandia existed over the Lord Howe hotspot. One rhyolite sample has been dated at 97 million years drilled on the southern Lord Howe Rise. [6] Lord Howe Island was the last volcano to erupt on the rise 6.5 million years ago. [4]

Islands, reefs and seamounts

Lord Howe Island and Ball's Pyramid cap a seamount towards the central east of the rise in an area known as the Lord Howe platform. The Lord Howe Seamount Chain extends northwards along the rise. The seamounts provide habitat to a diverse range of marine species which attracts commercial fishers, but cover a very small area, less than 1% of the total area of Lord Howe Rise. [7]

Further north is the Elizabeth and Middleton part of the Coral Sea Islands, which together with reefs around Lord Howe Island are the most southern coral reefs on Earth. [8]

Environment

The seabed on the rise is mostly sandy mud with some volcanic outcrops, gravel and boulders. [2]

The doubleheader fish, Coris bulbifrons , is endemic to reefs on the Lord Howe Rise and the West Norfolk Rise. [9]

Resources

Much of the basin remains unexplored in relation to oil and gas reserves. [10]

See also

Related Research Articles

<span class="mw-page-title-main">Tasman Sea</span> Marginal sea of the South Pacific between Australia and New Zealand

The Tasman Sea is a marginal sea of the South Pacific Ocean, situated between Australia and New Zealand. It measures about 2,000 km (1,200 mi) across and about 2,800 km (1,700 mi) from north to south. The sea was named after the Dutch explorer Abel Janszoon Tasman, who in 1642 was the first known person to cross it. British explorer Lieutenant James Cook later extensively navigated the Tasman Sea in the 1770s during his three voyages of exploration.

<span class="mw-page-title-main">Guyot</span> Isolated, flat-topped underwater volcano mountain

In marine geology, a guyot, also called a tablemount, is an isolated underwater volcanic mountain (seamount) with a flat top more than 200 m (660 ft) below the surface of the sea. The diameters of these flat summits can exceed 10 km (6.2 mi). Guyots are most commonly found in the Pacific Ocean, but they have been identified in all the oceans except the Arctic Ocean. They are analogous to tables on land.

<span class="mw-page-title-main">Seamount</span> Mountain rising from the ocean seafloor that does not reach to the waters surface

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The South Tasman Rise is an area of seafloor that lies 550 km south of Hobart, Tasmania in the Southern Ocean where water depths are about 1,500 metres. The South Tasman Rise is also known as the Tasmania Ridge or South Tasmania Ridge. The South Tasman Rise is a sunken landbridge that used to connect Tasmania to Antarctica.

<span class="mw-page-title-main">Campbell Plateau</span> Large oceanic plateau south of New Zealand and the Chatham Rise

The Campbell Plateau is a large oceanic plateau south of New Zealand and the Chatham Rise. It originated in the Gondwanan breakup and is part of Zealandia, a largely submerged continent. The above sea level parts of the plateau — the Bounty Islands, Antipodes Islands, Auckland Islands and Campbell Island — form part of the New Zealand Subantarctic Islands which were declared a World Heritage Site in 1998. Large parts of the Campbell Plateau lie less than 1000 m below sea level. It rises to 500 m at the Pukaki Rise and emerges above sea level at the Auckland and Campbell Islands.

The Lord Howe Seamount Chain formed during the Miocene. It features many coral-capped guyots and is one of the two parallel seamount chains alongside the east coast of Australia; the Lord Howe and Tasmantid seamount chains both run north-south through parts of the Coral Sea and Tasman Sea. These chains have longitudes of approximately 159°E and 156°E respectively.

<span class="mw-page-title-main">Lansdowne Bank</span>

Lansdowne Bank, sometimes called Landsdowne Bank, is an extensive submerged bank located between the main island of New Caledonia and the Chesterfield Islands, in the easternmost part of the Coral Sea. It covers an area of 4,300 km2 (1,660 sq mi), making it one of the largest banks of the world, has general depths of 60 to 80 metres (197–262 ft), and a largely sandy bottom. Two reefs mark the shallowest spots of the bank, but they are still submerged at low tide.

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<span class="mw-page-title-main">Geology of the Pacific Ocean</span> Overview about the geology of the Pacific Ocean

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The Norfolk Marine Park is an Australian marine park located in the waters immediately offshore of Norfolk Island, an external territory of Australia. The marine park extends 700 km (430 mi) in a north–south direction and covers an area of 188,444 km2 (72,759 sq mi). The park is assigned IUCN category IV and is one of 8 parks managed under the Temperate East Marine Parks Network.

The Lord Howe Marine Park is an Australian marine park located about 550 km (340 mi) offshore of New South Wales, near Lord Howe Island. The marine park covers an area of 110,126 km2 (42,520 sq mi), encompassing the smaller Lord Howe Island Marine Park, and is assigned IUCN category IV. It is one of 8 parks managed under the Temperate East Marine Parks Network.

<span class="mw-page-title-main">Joseph Gilbert Seamount</span> Continental fragment seamount west of New Zealand

Joseph Gilbert Seamount is a large seamount in the Tasman Sea located 450 km (280 mi) west of the South Island of New Zealand at the southern edge of the Lord Howe Rise. It has an elongated northwest–southeast trend, covering an area of about 11,500 km2 (4,400 sq mi) and rising to 2,400 m (7,900 ft) below sea level.

<span class="mw-page-title-main">Geology of New Caledonia</span>

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<span class="mw-page-title-main">Gifford Guyot</span> Seamount east of Australia

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<span class="mw-page-title-main">Geology of Zealandia</span> Geology of continental crust containing New Zealand and New Caledonia

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<span class="mw-page-title-main">Three Kings Ridge</span> Deep sea plateau, north of New Zealand

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References

  1. 1 2 "Lord Howe Rise". Regional petroleum geology of Australia. Geoscience Australia. 16 June 2003. Archived from the original on 13 March 2012. Retrieved 2007-04-19.
  2. 1 2 Harris, Peter T.; Scott L. Nichol; Tara J. Anderson; Andrew D. Heap (2011). "57: Habitats and Benthos of a Deep Sea Marginal Plateau, Australia". Seafloor Geomorphology As Benthic Habitat: GeoHAB Atlas of Seafloor Geomorphic Features and Benthic Habitats. Elsevier. p. 777. ISBN   978-0123851406 . Retrieved 26 June 2013.
  3. 1 2 3 Przeslawski, Rachel; Williams, Alan; Nichol, Scott L.; Hughes, Michael G.; Anderson, Tara J.; Althaus, Franziska (2011). "Biogeography of the Lord Howe Rise region, Tasman Sea". Deep Sea Research Part II: Topical Studies in Oceanography. 58 (7–8): 959–969. Bibcode:2011DSRII..58..959P. doi:10.1016/j.dsr2.2010.10.051. ISSN   0967-0645.
  4. 1 2 Mueller-Dombois, Dieter (1998). Vegetation of the Tropical Pacific Islands. Springer. p. 167. ISBN   0387983139 . Retrieved 26 June 2013.
  5. Mortimer, N. (2004). "Basement gabbro from the Lord Howe Rise". New Zealand Journal of Geology and Geophysics. 47 (3): 501–507. doi:10.1080/00288306.2004.9515072. S2CID   140602722.
  6. 1 2 Mortimer, N.; Turnbull, R. E.; Palin, J. M.; Tulloch, A. J.; Rollet, N.; Hashimoto, T. (2015). "Triassic–Jurassic granites on the Lord Howe Rise, northern Zealandia". Australian Journal of Earth Sciences. 62 (6): 735–742. doi:10.1080/08120099.2015.1081984. S2CID   131376941.
  7. Harris, P.T., 2011. Benthic environments of the Lord Howe Rise submarine plateau: Introduction to the special volume. Deep-Sea Research Part II 58, 883–888
  8. Woodroffe, C.D., Dickson, M.E., Brooke, B.P., Kennedy, D.M., 2005. Episodes of reef growth at Lord Howe Island, the southernmost reef in the southwest Pacific. Global and Planetary Change 49, 222–237
  9. Gibson, Robin N.; R. J. A. Atkinson; J. D. M. Gordon (2011). Oceanography and Marine Biology, Volume 49. CRC Press. p. 216. ISBN   978-1439853641 . Retrieved 26 June 2013.
  10. Misha Schubert and Barry Fitzgerald (2009-04-22). "National bonanza sitting on shelf". The Age . Fairfax Digital . Retrieved 2009-12-04.