Under the water column in the southwestern Pacific Ocean, a sunken continent was discovered. A group of American researchers who have studied the geological history of New Zealand and satellite data insists on this. How scattered fragments have grown together in 20 years and why is it beneficial for this island state to be on a separate continent.
This is more comfortable
The name Zealandia was first proposed by the American scientist Bruce Lundike in 1995. He studied the process of splitting the eastern part of the ancient supercontinent of Gondwana, from which the modern lands of the southern hemisphere and part of the northern hemisphere began to form about 150 million years ago. By the word "Zealand" Lundike meant New Zealand and a number of geological features under water: the Chatham Rise, Lord Howe Ridge, Phoenix Plateau and Campbell Plateau. “I came up with this term for the sake of convenience,” Lundijk himself explained. “They are parts of one whole, judging by Gondwana. So I thought: why separate names for fragments of the whole?"
But over time, evidence began to accumulate that a convenient word could give a name to a continent that has long been considered a "shard" of Australia. Geological processes take a long time by human standards: these pieces of land were separated from each other over 30 million years, and this process ended 53 million years ago. 23 million years ago, the current contender for the title of a new continent went under water. Now only a small part of it is visible: the islands of New Zealand and New Caledonia. Almost 95% of its territory is hidden by the waters of the Tasman Sea, which now separates Australia and New Zealand, and the Pacific Ocean.
It's all about size
It is worth noting that Lundijk referred to these fragments as the continental region. The earth's crust there belongs to the continental type, volcanic, sedimentary and metamorphic rocks were found, formed under the influence of temperature and pressure. The land, that is, the islands, rose sufficiently out of the water. There was only one criterion that did not meet the part that once made up 5% of Gondwana, namely the area. According to certain geological indicators, the area of the continent cannot be less than 3 million square meters. km.
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Now, thanks to researchers from the US Geological Society, this issue has also been resolved. It turned out that the area of the Zeeland continental crust, which differs from the oceanic one in lower density and greater thickness, is 4.9 million square meters. km.
Map of tectonic plates and continents, including the continent of Zealand / geosociety.org
In order to study in more detail where the boundaries of the alleged sunken continent are located, scientists resorted to the help of a satellite. With the new data, they refined the bathymetric map showing the bottom topography. In the opinion of the Americans, their predecessors were hindered by the fact that part of the continental crust of Zealand was cut by the oceanic crust, but they do not consider the denser "admixture" to be a significant circumstance.
Bug fixes and resource sharing
As follows from the information posted on the website of the Royal Research Institute of New Zealand, for local geologists the existence of the seventh continent is not news for a long time. The author of the work also knows about it. "New Zealand geologists must be wondering why the fuss is so high," said US research leader Nick Mortimer.
Scientists did not set themselves the goal of discovering a new continent. Rather, the work begun after the first measurements of depths and bodies of water in the region in 2002 served to restore a kind of scientific justice. The authors explain why it is important to recognize the existence of a seventh continent. Zealand, as a separate continent, albeit the smallest, fits into the ideas that science has determined. And its exclusion from this number threatens geology with inaccuracies in further research.
Researchers argue that not recognizing Zealand as a continent means ignoring important factors in the Mesozoic history of Gondwana (252-66 million years ago). Now, if the scientific community agrees with the results of the research group, scientists will be able to fill the noticeable gaps in the past of the supercontinent, eastern Australia and western Antarctica.
But science is science, and a discovery can have economic consequences. The boundaries of the continents are used internationally to decide which state the natural resources belong to. Recognition of the status of a sunken landmass is likely to place any minerals found in the underwater continent at New Zealand's disposal.
Anastasia Klepneva