A new ocean mapping expedition draws the borders of Zealand, the submerged “lost continent” that hosts New Zealand and the territory of New Caledonia in the South Pacific.
Zealand separated from the supercontinent of Gondwana between 79 and 83 million years ago. Apart from New Zealand and New Caledonia, this fragment of the continental crust is now at the bottom of the ocean. It is not the only part of the continental crust that has separated from the larger continent, but it is the largest with 4.9 million square kilometers of 1.9 million square kilometers. It is six times larger than the next largest continental fragment, the microcontinent of Madagascar.
Zealand, also known as Te Riu-a-Māui in Maori, was granted continental status in 2017. Since then, researchers have been working on mapping the lost continent – it is not an easy feat, because 94% is under water.
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Now Derya Gürer, a country scientist from the University of Queensland in Australia, and her colleagues have collected new data on the northwestern edge of Zealand, located in the sea in the Coral Sea Marine Park in Queensland. The researchers spent 28 days aboard the Falkor exploring the region, mapping 37,000 square miles.
“Our expedition collected topographic and magnetic data from the seabed to gain a better understanding of how a close link was formed between the Tasmanian and Coral Seas in the Cato Basin region – a narrow corridor between Australia and Zealand,” Gürer he said in a university statement.
The area between the Australian Plate and Zealand is probably very complicated, Gürer said. Several microcontinents were probably submerged there, which were vaccinated against major continental masses when Australia was liberated Gondwana. (The supercontinent encompassed present-day South America, Africa, Antarctica, Australia, Zealand, Arabia, and the Indian subcontinent.) These fragments of the continental crust differ from the surrounding oceanic seabed crust, which is denser and thinner than the continental crust.
Performed in collaboration with the Schmidt Ocean Institute, the mapping was part of the Seabed expedition to seabirds. The mapping data will also go into a larger project, the Seabed 2030 collaboration, which aims to create a publicly available, comprehensive map of the ocean floor by 2030. According to the National Oceanic and Atmospheric Administration (NOAA), less than 10% of the seabed has been mapped by modern sonar methods. which use sound to detect submarine topography. The Seabed to Seabird expedition collected not only information on the topography, but also data on the intensity of the magnetic field in the area. Because the oceanic and continental crusts are made up of different concentrations of minerals with different magnetic signatures, this data will allow researchers to reconstruct broken fragments of Gondwana.
“The seabed is full of clues to understanding the complex geological history of the Australian and Zealand continental plates,” Gürer said.
Originally posted on Live Science.