Lord Howe Rise
| Lord Howe Rise | |
|---|---|
| Stratigraphic range: | |
 The Lord Howe Rise is part of the continent known asZealandia. | |
| Location | |
| Coordinates | 28°S161°E/ 28°S 161°E |
| Region | South Pacific,Coral Sea,Tasman Sea |
| Type section | |
| Named for | Lord Howe Island |
TheLord Howe Riseis adeep seaplateauwhich extends from south west ofNew Caledoniato theChallenger Plateau,west ofNew Zealandin the south west of thePacific Ocean.To its west is theTasman Basinand to the east is theNew 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 ofZealandia,a much largercontinentthat is now mostly submerged, and so is composed ofcontinental 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]
Geology[edit]
The Lord Howe Rise is associated withseafloor spreadingwhich 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 containedgranitepebbles that were in the range 216–183 million years old.[6]It wasriftedaway fromEastern Australiain association with amid-ocean ridgethat was active from 80 to 60 million years ago, and now lies 800 kilometres offshore frommainland Australia.
The Lord Howe Rise contains a line ofseamountscalled theLord Howe Seamount Chainwhich formed during theMioceneperiod when this part of Zealandia existed over theLord Howe hotspot.Onerhyolitesample has been dated at 97 million years drilled on the southern Lord Howe Rise.[6]Lord Howe Islandwas the last volcano to erupt on the rise 6.5 million years ago.[4]
Islands, reefs and seamounts[edit]
Lord Howe IslandandBall's Pyramidcap a seamount towards the central east of the rise in an area known as the Lord Howe platform. TheLord Howe Seamount Chainextends 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 theElizabethandMiddletonpart of theCoral Sea Islands,which together with reefs aroundLord Howe Islandare the most southern coral reefs on Earth.[8]
Environment[edit]
Theseabedon 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 theWest Norfolk Rise.[9]
Resources[edit]
Much of the basin remains unexplored in relation to oil and gas reserves.[10]
See also[edit]
- Chatham Rise– An area of ocean floor to the east of New Zealand, forming part of the Zealandia continent
- Norfolk Ridge– Submarine ridge between New Caledonia and New Zealand
- South Tasman Rise– Area of seafloor about 1500 m deep south of Hobart, Tasmania in the Southern Ocean
References[edit]
- ^ab"Lord Howe Rise".Regional petroleum geology of Australia.Geoscience Australia.16 June 2003. Archived fromthe originalon 13 March 2012.Retrieved2007-04-19.
- ^abHarris, 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.ISBN978-0123851406.Retrieved26 June2013.
- ^abcPrzeslawski, 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.ISSN0967-0645.
- ^abMueller-Dombois, Dieter (1998).Vegetation of the Tropical Pacific Islands.Springer. p. 167.ISBN0387983139.Retrieved26 June2013.
- ^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.S2CID140602722.
- ^abMortimer, 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.S2CID131376941.
- ^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
- ^Woodroffe, C.D., Dickson, M.E., Brooke, B.P., Kennedy, D.M., 2005. Episodes of reef growth atLord Howe Island,the southernmost reef in the southwest Pacific. Global and Planetary Change 49, 222–237
- ^Gibson, Robin N.; R. J. A. Atkinson; J. D. M. Gordon (2011).Oceanography and Marine Biology, Volume 49.CRC Press. p. 216.ISBN978-1439853641.Retrieved26 June2013.
- ^Misha Schubert and Barry Fitzgerald (2009-04-22)."National bonanza sitting on shelf".The Age.Fairfax Digital.Retrieved2009-12-04.