Chatham Rise

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Topographic map of Zealandia with the Chatham Rise stretching to the east

The Chatham Rise is a mountain range east of New Zealand lying 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 .

geography

The Chatham Rise extends east of the Banks Peninsula about 1450 km in an easterly direction and borders in the north on the Hikurangi Trench and the Hikurangi Plateau and in the south on the Bounty Trough . East of the Chatham Rise begins the deep sea of ​​the southern Pacific Ocean . The mountain range rises in the north and south from a depth of 2000 to 2500 m down to between 200 and 500 m below sea level, with two flat elevations in the western part of the Chatham Rise , the Mernoo Bank and the Veryon Bank , even less than 100 m below the sea surface.

The south-eastern flanks of Chatham Terrace and the eastern tip drop down to around 4,000 m. The mountain range has a maximum width of 330 km and rises around 850 km east of the South Island of New Zealand with the Chatham Islands from the Pacific Ocean.

geology

Geological investigations of the seabed, 650 km east of Chatham Island at the eastern tip of the Chatham Rise , see Takahe Dredge Site , have shown that the granite stones have the same composition and, at 97 million years, the same age as granites in the Canterbury region and Marlborough were found and shale and sediments from other sites are consistent with those in the Chatham Islands . The rocks covered by sediments are between 90 and 100 million years old and date from the Cretaceous period .

Scientists also found the remains of a shield volcano that was active 80 to 85 million years ago south of Chatham Island and Pitt Island . But today, more than 1000 km away from the active Alpine Fault , where the Pacific Plate and the Australian Plate shift against each other, the area around the Chatham Islands is considered to be tectonically stable, and so is the vast majority of the Chatham Rise .

Phosphate occurrence

Around 450 km east of Christchurch , on the Chatham Rise, over an area of ​​820 km 2 and a depth of 400 m, there is a phosphate deposit that comprises 23.4 million tons of the raw material on the most exploitable area. The deposit, formed seven to twelve million years ago, is expected to be exploited two years after final approval by Chatham Rock Phosphate (CRP). After the approval by the New Zealand Petroleum & Minerals Office, which was already granted in 2013, there was considerable opposition from New Zealand environmental protection organizations and the fishing industry, as a result of which the approval by the Environmental Protection Authority (EPA) was revoked in 2015. However, the company stuck to the project and applied for approval to mine the phosphate again and expects a positive decision in 2018.

Flora and fauna

The Chatham Rise lies in the convergence zone of the northern subtropical nitrate-depleted water and the southern subarctic nitrate-rich water. This mixing leads to an increased production of phytoplankton in the region of the Chatham Rise, as a result of which a complex ecosystem with many different marine life, seabirds and marine mammals has formed in the region.

The New Zealand fishing industry uses the Chatham Rise as a fishing ground due to the abundance of fish there. In order not to burden the ecosystem too much, catch quotas have been set for the predominantly caught fish species. Primarily fish are caught in the region such as: Hoki ( Macruronus novaezelandiae ) Orange Roughy ( Hoplostethus atlanticus ), Pseudocyttus maculatus , Allocyttus niger and Neocyttus rhomboidalis , spiny dogfish (Squalidae) and Grenadiers (Macrouridae) and as bycatch: six different types of black heads ( Alepocephalidae), deep sea flatheads (Bembridae), various species of sea ​​cats (Chimaera) and the pit eel species Diastobranchus capensis .

Cuttlefish, important to any marine ecosystem as they are a food source for numerous predators, come in the species: Arrow Squid ( Nototodarus sloani ), Onykia ingens ( Moroteuthis ingens ), Onykia robsoni ( Moroteuthis robsoni ), Neon Flying Squid ( Ommastrephes bartrami ), and giant squid ( Architeuthis ).

While the New Zealand fur seal ( Arctocephalus forsteri ), the New Zealand sea lion ( Phocarctos hookeri ) and the southern elephant seal ( Mirounga leonine ) are rare, whales and dolphins are common in the region. So the dolphins could Bottlenose dolphin ( Tursiops truncatus ), hourglass dolphin ( Lagenorhynchus cruciger ) and southern right whale dolphin ( Lissodelphus peronii ) are sighted in the region and numerous Walgattungen, like the blue whale ( Balaenoptera musculus ), the fin whale ( Balaenoptera physalus ), the sperm whale ( Physeter macrocephalus ), the killer whale ( Orcinus orca ) and the sei whale ( Balaenoptera borealis ), to name a few.

The number of different seabird species also shows a considerable diversity of species with 70 species.

literature

Web links

  • Ashley Rowden : Sea floor - Chatham Rise . In: Te Ara - the Encyclopedia of New Zealand . Ministry for Culture & Heritage , June 12, 2006, accessed March 10, 2017 .

Individual evidence

  1. ↑ Mortimer et al. 10 co-authors: Zealandia: Earth's Hidden Continent . In: GSA Today . 2017, p.  1 .
  2. ↑ Jeremy Titjen : Tertiary limestones and sedimentary dykes on Chatham Islands, southwest Pacific Ocean, New Zealand . Ed .: University of Waikato . Hamilton 2007, p.  13 (English, online [PDF; 26.3 MB ; accessed on March 10, 2017] Thesis for Master of Science in Earth and Ocean Sciences ).
  3. ↑ a b c d Mortimer, Campbell : Zealandia - Our Continent Revealed . 2014, p.  74-76 .
  4. ↑ a b Coordinates and longitudes of the Chatham Rise were made by Google Earth .
  5. ↑ a b Fact Sheet . Chatham Rock Phosphate , February 2017, accessed March 10, 2017 .
  6. ^ Submission to the Environmental Protection Authority on the application by Chatham Rock Phosphate for a marine consent to mine phosphate in the Chatham Rise . (PDF) deepwater group , July 10, 2014, accessed on March 10, 2017 .
  7. ^ Seabed mining of Chatham Rise denied . The Fishing Website , February 11, 2015, accessed March 10, 2017 .
  8. ^ Pinkerton : A balanced trophic model of the Chatham Rise, New Zealand . 2011, p.  4 .
  9. ^ Pinkerton : A balanced trophic model of the Chatham Rise, New Zealand . 2011, p.  19 .
  10. ^ Pinkerton : A balanced trophic model of the Chatham Rise, New Zealand . 2011, p.  23 .
  11. ^ Pinkerton : A balanced trophic model of the Chatham Rise, New Zealand . 2011, p.  17 .
  12. ^ Pinkerton : A balanced trophic model of the Chatham Rise, New Zealand . 2011, p.  14-15 .
  13. ^ Pinkerton : A balanced trophic model of the Chatham Rise, New Zealand . 2011, p.  13 .

Coordinates: 43 ° 46 ′ 0 ″  S , 174 ° 1 ′ 0 ″  E