Campbell Plateau

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Topographic map of Zealandia with the Campbell Plateau to the south

The Campbell Plateau is a sub- sea ​​level mountainous plateau south to southeast of New Zealand . It is part of the 4.9 million square kilometer and 94% below sea level area that scientists refer to as Zealandia and that is being promoted as a continent .

geography

The Campbell Plateau , which has almost the shape of an obtuse triangle , begins around 250 km south of Stewart Island and extends from there around 700 km to the south. The east-west extension is around 1150 km and the extension from the southernmost tip to the eastern is around 1500 km.

The elevated areas of the submarine plateau lie between 0 and 1000 m depth and with the Auckland Islands , Campbell Island , Antipodes Islands and Bounty Islands (listed from west to east) parts of the plateau even protrude from the Pacific Ocean .

Larger depressions in the Campbell Plateau include the Great South Basin , which lies south of the South Island from New Zealand to west of the Auckland Islands and continues east of it in the Pukaki Basin , the Campbell Basin , which is south of Campbell Island and the Outer Campbell Basin , which is located east of Campbell Island .

In the west, the slopes of the plateau drop to between 1500 and 4000 m depth, while in the southeast they drop to a depth of around 4000 m. To the north of the plateau is the 800 km long and 250 km wide Bounty Trough , which brings it to a depth of between 1000 and 4000 m.

geology

Most of the Campbell Plateau consists of a continental crust between 20 and 25 km thick , which decreases at the edges to between 10 and 15 km thick. The base rock of the crust consists mainly of two types of rock, silicate- containing rocks with igneous rocks in between and quartz-like metasedimentary rocks. They are comparable to those found in parts of the South Island of New Zealand. The igneous rock found on Auckland Island is similar to the rock found on Stewart Island , the Snares Islands and in the western part of the South Island, granodiorites from Bounty Island are similar to those from the Foveaux Strait area and the metasedimentary rocks from Campbell Island , from various boreholes in the lake bed of the plateau and from the seabed near the Bounty Islands are comparable to those on the West Coast of the South Island and date from the Mesozoic to the late Paleozoic .

Magnetic anomalies

In the southern part of the South Island into the Great South Basin and in the area of ​​the Campbell Plateau there are two magnetic anomaly systems , the Stokes Magnetic Anomaly System (SMAS) and the Campbell Magnetic Anomaly System (CMAS). Both systems have different characteristics in gravitation and in magnetism . While volcanic activity in the Pliocene is suspected in the case of the CMA system and a crust underlying the plateau was found under the existing continental crust, the area of ​​the SMA system was spared. In addition, the Great South Basin is considered the part of Zealandia with the thinnest and weakest crust. It cannot currently be explained why there is an inserted crust under the Campbell Plateau and why the Great South Basin lacks it.

literature

Individual evidence

  1. ↑ Mortimer et al. 10 co-authors: Zealandia: Earth's Hidden Continent . In: GSA Today . 2017, p.  1 .
  2. ↑ a b Coordinates and longitudes of the Campbell Plateau were determined by Google Earth .
  3. ^ Mortimer, Campbell : Zealandia - Our Continent Revealed . 2014, p.  54 .
  4. ^ Henry Moir Pantin : Campbell Plateau . In: Alexander Hare McLintock (Ed.): An Encyclopaedia of New Zealand . Wellington 1966 ( online [accessed March 12, 2017]).
  5. ^ Mortimer, Campbell : Zealandia - Our Continent Revealed . 2014, p.  80 .
  6. ^ Bounty Trough . In: GEBCO - Undersea Feature Names Gazetteer . National Centers for Environmental Information (NOAA), accessed on March 12, 2017 (English, interactive map for selecting the geographic object).
  7. ^ Mortimer, Campbell : Zealandia - Our Continent Revealed . 2014, p.  68 .
  8. ↑ a b Beggs, Challis, Cook : Basement geology of the Campbell Plateau: ... . 1990, p.  401 .
  9. ↑ Grobys, Gohl , Uenzelmann-Neben , Davy, Barker : Extensional and magmatic nature of the Campbell Plateau and Great South Basin from deep crustal studies . 2008, p.  223 .

Coordinates: 51 ° 0 ′ 0 ″  S , 172 ° 1 ′ 0 ″  E