Scientists Have Finished Mapping Out the Continent of Zealandia

In this world, a lot has remained unidentified or hidden. The earth’s surface is divided into two types of crust: continental and oceanic. For the past several years, scientists have emphasized measuring and modeling the aspects of plate tectonics. This is to understand continental rifting, continent-ocean boundaries, and the number of micro-continental breakups. That’s when they discovered the eighth continent, Zealandia. Recently, scientists and researchers from GNS Science have completed drawing the map of the continent hidden beneath the Pacific Ocean.

The discovery of Zealandia

The history of Zealandia, or Te Riu-a-Māui in Maori, is quite ancient. Several research and scientific developments helped to determine the location of the continent. Some say a Dutch sailor, Abel Tasman, discovered it in 1642 AD, but Scottish naturalist James Hector established its existence in 1895. Both arrived in New Zealand, the southern coast of the chain of the Zealandia islands.

Later in 2014, New Zealand researchers Nick Mortimer and Hamish Campbell, along with other geological researchers, proved that Zealandia can be classified as a separate continent. In 2017, they outlined the characteristics from its thick and geologically varied crust to its size that set it apart from Australia. The continent was thought to have formed around 83 million years ago. Its journey began around 100 million years ago when the supercontinent of Gondwana started to break up. It was once laid directly to its northwest and southwest regions that is now known as Australia and Antarctica.

Drawing the map

Zealandia has an estimated 4.9 million square kilometers, or 95% of its land, submerged under the Pacific Ocean for the past 25 million years. This makes it a big challenge to complete the map since only about 5% of the land is peaking above the water. The only reason that it became possible in 2023 is just because of technological advancement. It is a cumulative operation of different measurements:

1. Global gravity and bathymetry maps: derived from satellite microgravity/geodesy measurements that helped to measure ship track depth sounding and the derivation of water depth.
2. Global Magnetic maps: a mix of satellite and ship-borne proton precession for substantial computing resources to process the data into usable forms.
3. Research ship equipped with specialist instruments: this includes multibeam echo sounding for mapping the seabed, active source seismic reflection equipment for ultrasound of the earth’s layer, and rock dredges for collecting rock samples.
4. Seabed boreholes: used for drilling and investigating the samples of the rocks.
5. Mass spectrometers: measuring isotopic ages of rocks with X-ray and electron beam high vacuum instruments.

Volcanos and rock beds

I got a chance to get in touch with Nick Mortimer. He said it was “fair to say it’s the combination of remote sensing and direct sampling that allows the map to be made.” The new map of Zealandia is the accumulated result of bathymetry and tectonic evolution. It gives an accurate and updated picture of the geology of New Zealand as well as the Southwest Pacific area. The map also explains the setting of the volcanoes, plate boundaries, and sedimentary basins.

Its strong magnetic signature revealed the volcanic areas even though most lie underwater. The magnetic anomalies of these areas remain in the same basalt lava rocks surfaced by rock dredges. The seabed rock samples also include some granite that belongs to a 4000km transcontinental belt. All the samples adjoined the final dots of the map. Through this discovery, the geologists could finally dray the full map, curving the stretch of 250 to 100-million-year-old granite backbone. Hence, Zealandia has become the world’s first undersea continent to be completely mapped.

YouTube: Zealandia | Earth’s Forgotten eighth continent

Photo credit: The images used in the article are owned by GNS Science New Zealand and have been provided for press usage.
Sources: ArabiaWeather.com / The Geological Society of America / Satellite Geodesy / National Centers for Environmental Information / The University of Rhode Island