Submerged about two-thirds of a mile (more than a kilometre) under the sea, Zealandia is a mass of continental crust that subsided after breaking away from Gondwanaland 83–79 million years ago. The team of 11 scientists that took part in the 2017 expedition to uncover the hidden secrets of this almost submerged land are striving to recognise this landmass as the eighth continent. The proposed continent is situated to the east of Australia and derives its name from a few of its highest mountain ranges: the land that comprises New Zealand and New Caledonia.
According to Martin Ross, an associate professor of Geology at the Northeastern University, Zealandia conforms to all the features that a continent should possess:
It must be highly elevated above the surrounding oceanic crust.
It must consist of a broad range of siliceous igneous, metamorphic, and sedimentary rocks. (Oceanic crust consists of igneous rocks—basalt and gabbro—and is poor in silica.)
It must have a thicker crust compared to the oceanic crust.
And it must have well-defined limits and be relatively large compared to micro-continents and continental fragments.
There has been a string of debates among the geologists whether Zealandia should be considered as a continent, microcontinent, or submerged continent, considering that about 94% of the landmass is submerged under water. Apart from this classification, Ross believes that the study of Zealandia could lead to a deeper understanding of tectonic evolution as he believes it to be “the youngest and thinnest continent.”
On this note, Ross explains, “Rather than being concentrated at rifts and failed rifts like the other continents, the extension of Zealandia as it thinned and separated from the ancient supercontinent Gondwana was spread over a broader zone.”
This expedition can aid in understanding the formation of continents and the breakup of supercontinents and in the future may lead to Zealandia being classified as a continent.
Dibyasha Das