Is Zealandia is a new continent

Is New Zealand a continent in its own right?

An area the size of India, east of Australia, is said to be an independent continent. This is what at least one group of geologists from New Zealand and New Caledonia argues. What is to be made of this thesis?

Today, geological discoveries are almost only possible in the deep sea. This is why the seabed, which is hidden deep under water, has been measured intensively for years. Now researchers from New Zealand and New Caledonia conclude from the results that a huge piece of solid rock east of Australia is a continent of its own. A US geologist suggested the appropriate name, “Zealandia” 22 years ago. But only now have the findings been sufficient to confirm his hypothesis, write the researchers in "GSA Today", the magazine of the US geological society.1

"Zealandia" meets all geological criteria

According to the researchers, Zealandia meets all the geological criteria that the other six continents would meet (North and South America, Eurasia, Africa, Antarctica and Australia). This includes that around New Zealand an elongated plateau rises around one kilometer above the sea floor. As with all continents, the reason for this lies in the isostatic buoyancy of the rock. Because continental rocks such as granite, gneiss or sediments have a lower density than typical ocean floors, which almost always consist of dense basalt. Its considerable size distinguishes Zealandia from continental fragments, which have repeatedly broken off as smaller parts of large continents during the history of the earth. Madagascar is an example of such a splinter. Zealandia, on the other hand, is almost five million square kilometers larger than India, which, until it collided with Asia a few million years ago, was also considered an independent continent.

Zealandia differs most from the other continents by its massive water cover: 94 percent of the area is under water. But that is not at all unusual, argue the scientists. Because geology also assigns shelf areas offshore to the continents. The Antarctic, for example, has a shelf base that makes up a good half of the area of ​​the continent.

In terms of plate tectonics, Zealandia is independent

Besides New Zealanders and New Caledonians, geologists in particular are likely to be interested in the new continent. The researchers involved complain that studies on moving continents have so far hardly taken into account the plate-tectonically independent Zealandia. The new continent played a role in the history of the earth: Zealandia once made up five percent of the area of ​​the supercontinent Pangea before the continent separated in the Cretaceous period, was elongated by external forces and finally sank largely under the Pacific.

1GSA Today, v. 27 (2017).