Norfolk Ridge

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Topographic map of Zealandia with the Norfolk Ridge stretching south from New Caledonia to the south

The Norfolk Ridge is a mountain range below sea level . It belongs to the 4.9 million square kilometer and 94% below sea level area that scientists call Zealandia and that is being promoted as a continent .

Origin of name

The submarine ridge was named after the island of Norfolk Island , which is part of the submarine mountain range.

geography

The Norfolk Ridge is located south of New Caledonia and begins at the southernmost point of the island. From there, the mountain ridge stretches over 1080 km directly to the south ( geographic coordinates 22 ° 36 'S, 167 ° 10' E , geographic coordinates 32 ° 18 'S, 168 ° 07' E ). Australia , whose 200-nautical-mile zone includes the southern half of the ridge, is 1,300 km to the west and the southernmost point of the Norfolk Ridge is around 480 km to the northwest of New Zealand . West of the Norfolk Ridge is the New Caledonia Trough , adjoining the West Norfolk Ridge to the south and the North Norfolk Basin and the South Norfolk Basin east of the ridge .

The West Norfolk Ridge is sometimes counted as part of the Norfolk Ridge , which would increase the length of the ridge to 1,600 km.

The base of the mountain ridge is between 50 and 100 km wide and the entire length of the ridge is between 500 and 2000 m below sea level. The highest point of the Norfolk Ridge is the island of Norfolk Island , which belongs to Australia, with its adjoining small rock islands. The island rises 319  m from the Pacific Ocean with Mount Bates .

geology

Geologically speaking, the archipelago of New Caledonia belongs to the Norfolk Ridge and represents its continuation above sea level to the north. Both belong to the Australian plate and in contrast to New Zealand there is no active volcanism and only little seismic activity. The base rock consists of greywacke and slate and is similar to that of New Zealand. Norfolk Island is of volcanic origin and is two to three million years old.

The surface structure of the mountain ridge is rugged with steep flanks to the east and west. Even if the Norfolk Ridge has a different surface structure than the Lord Howe Rise , the structures of the continental crust are similar, which leads to the theory that both elevations were originally united and separated by the formation of the New Caledonia Trough .

Marine fauna

Until 2003 the marine fauna in the Norfolk Ridge area had been little explored. That is why the New Zealand Ministry of Fisheries, in cooperation with the National Oceans Office of Australia , started the NORFANZ project in May 2003, which will monitor marine fauna in the areas of the Norfolk Ridge and the Lord Howe Rise for two months (May 9th to June 7th 2003) should investigate. In a total of 14 different areas, ten in the Norfolk Ridge area and four in the Lord Howe Rise area , marine life was explored at depths between 100 and 2000 m. 590 different types of fish and 1305 different types of invertebrates were identified, 12% of the invertebrates were identified as new species and around 20% of the fish.

literature

  • J. Pinchin, D. Jongsma, JJ Petkovic: Seabed Margins and Resources Potential of Macquarie Ridge, Norfolk Ridge and Lord Howe Rise . Ed .: Department of Minerals and Energy . Australia October 1976 (English).
  • Malcolm R. Clark, Clive D. Roberts : Fish and invertebrate biodiversity on the Norfolk Ridge and Lord Howe Rise, Tasman Sea (NORFANZ voyage, 2003) . In: Ministry of Fisheries (ed.): New Zealand Aquatic Environment and Biodiversity Report . No. 28 , 2008, ISSN  1176-9440 (English, online [PDF; 14.6 MB ; accessed on March 15, 2017]).
  • Nick Mortimer , Hamish Campbell : Zealandia - Our Continent Revealed . Penguin Books , London 2014, ISBN 978-0-14-357156-8 (English).
  • Nick Mortimer et al. 10 co-authors: Zealandia: Earth's Hidden Continent . In: Geological Society of America (Ed.): GSA Today . Volume 27 number = Issue 3 (March / April), 2017, doi : 10.1130 / GSATG321A.1 (English, online [accessed March 15, 2017]).

Individual evidence

  1. ↑ Mortimer et al. 10 co-authors: Zealandia: Earth's Hidden Continent . In: GSA Today . 2017, p.  1 .
  2. ↑ a b Norfolk Ridge . In: GEBCO - Undersea Feature Names Gazetteer . National Centers for Environmental Information (NOAA), accessed on March 15, 2017 (English, interactive map for selecting the geographic object).
  3. ↑ a b Coordinates and longitudes of the Norfolk Ridge were made by Google Earth .
  4. ^ Ian J. Graham : A Continent on the Move . New Zealand Geoscience into the 21st Century . Ed .: Geological Society of New Zealand . Lower Hutt 2008, ISBN 978-1-877480-00-3 , pp.  38 (English).
  5. ↑ a b Pinchin, Jongsma, Petkovic: Seabed margins and Resources Potential of Macquarie Ridge, Norfolk Ridge and Lord Howe Rise . October 1976, p. 4 .
  6. ^ Fairway Basin and Ridge New Caledonia Basin and Norfolk Ridge . Geoscience Australia , accessed March 15, 2017 .
  7. ^ Mortimer, Campbell : Zealandia - Our Continent Revealed . 2014, p.  94 .
  8. ^ Mortimer, Campbell : Zealandia - Our Continent Revealed . 2014, p.  97 .
  9. ^ Clark, Roberts : Fish and invertebrate biodiversity on the Norfolk Ridge and Lord Howe Rise, Tasman Sea . 2008, p.  4 .
  10. ^ Clark, Roberts : Fish and invertebrate biodiversity on the Norfolk Ridge and Lord Howe Rise, Tasman Sea . 2008, p.  114 (Appendix 5).
  11. ^ Clark, Roberts : Fish and invertebrate biodiversity on the Norfolk Ridge and Lord Howe Rise, Tasman Sea . 2008, p.  6 .
  12. ^ Clark, Roberts : Fish and invertebrate biodiversity on the Norfolk Ridge and Lord Howe Rise, Tasman Sea . 2008, p.  113 (Appendix 5).