You might think you know all the continents, but what about Zealandia? In 2017, a previously unknown expanse of New Zealand’s shores made global headlines when it was unveiled to the world.
Zealandia, referred to as Te Riu-a-Māui in the Māori language, encompasses over 5 million square kilometers, dwarfing the subcontinent of India in size, being twice its magnitude.
The reason for this lies in the fact that a staggering 95 percent of its landmass is concealed beneath the southwest Pacific Ocean, having submerged eons before human beings walked the Earth. Only a substantial mountain chain, essentially comprising the two islands of New Zealand, along with some petite oceanic islands, protrudes above the water’s surface.
The newly discovered continent, Zealandia, remains shrouded in mystery due to its virtually inaccessible nature. Nevertheless, an international team of geologists has collaborated to create a novel geological map encompassing Zealandia. This map was fashioned through a fusion of ocean-recovered rock samples and advanced geophysical mapping techniques.
During their quest for samples, geologists identified extensive sandstone formations and deposits of basaltic rock pebbles along Zealandia’s outer boundaries. These sandstones are estimated to be approximately 95 million years old and contain older granite and volcanic pebbles, suggesting that when Zealandia was above sea level, it was traversed by rivers streaming from volcanic highlands and filling tectonic basins.
The volcanic highlands were an active geological feature at least 30 to 50 million years prior, but the erosion likely occurred when the sandstone layers were deposited.
Geologists posit that Zealandia underwent a gradual inundation roughly 40 million years ago. This conclusion is substantiated by the discovery of basalt pebbles linked to underwater volcanic activity.
The findings from this research, titled “Reconnaissance basement geology and tectonics of North Zealandia,” have been documented in the 2023 edition of the journal Tectonics.