In 2017, the scientific community echoed the description of a new continent almost totally submerged under the waters of the Pacific Ocean: Zealandia. We are talking about a land mass that extends from the northeast of Australia to beyond the south of New Zealand and with an extension that would be equivalent to about two-thirds the size of the Australian continent.
As we have already mentioned, Zealandia is a very unusual continent, since it is practically submerged under water and only its highest mountains emerge: New Zealand and New Caledonia. It should also be noted that there is also no consensus on the definition of a continent: while some refer to Zealandia as ‘the eighth continent’, others say that it would be the seventh and that the other six would be Africa, Eurasia, North America, South America, Antarctica. and Australia.
The existence of Zealandia has already been sensed since a scientific expedition recovered several samples from the ocean floor in the area in 1972, but it was not until 2017 that a team began to explore it in depth as part of the International Ocean Discovery Program. (IODP).
Since then, scientists have been studying thousands of microfossils from various holes in the seafloor of Zealand, and some of the results have just been published in the journal Geology . As revealed in the article, the continent would have arisen from two tectonic events. In the first place it would have separated from Australia and Antarctica 80 million years ago. Second, the same forces that started the formation of the Pacific Ring of Fire, an area of volcanoes and earthquakes located on the shores of that ocean, would also have acted on Zealandia.
“The results of these studies have changed the little that was known about this hidden continent”, explains Laia Alegret, paleontologist at the University Institute of Environmental Sciences of Aragon and one of the authors of the work. “They have allowed us to know how it evolved as an independent continent after separating from Australia and Antarctica 80 million years ago, how the depth of its seas changed over time, when it emerged and sank, conditioning the migrations of the species, ocean currents and global climate. In addition, it has been possible to determine the movement of the tectonic plates, which seems to be related to the formation of the Pacific Ring of Fire. These results provide information on climate change and on fundamental geological processes, with implications in the prevention of geological risks such as volcanism or earthquakes ”.
Zealandia and the Ring of Fire
The authors of this new work have found evidence suggesting that Zealandia was not always a submerged continent, since some of its regions rose above sea level between 50 and 35 million years. Subsequently, practically the entire continent ended up sinking at least one kilometer.
The processes that shaped Zealandia have a lot to do, as we have mentioned, with the mythical Pacific Ring of Fire, a region with intense seismic and volcanic activity. Although its formation is not known in detail, it is known that it would be the result of subduction processes, which occur when a tectonic plate sinks underground. Apparently, about 50 million years ago a subduction rupture event would have spread throughout the entire western Pacific.
“What is proposed is that the process would be similar to a super slow massive earthquake that resurrected ancient subduction faults that had lain dormant for millions of years, but began to move again,” explained in a press release from the Institute. University of Environmental Sciences of Aragon. “There is probably no current analog of this process, but the evidence from Zealand suggests that these events can dramatically alter the geography of the continents . This same event created natural resources, affected the global climate, changed the direction and speed of movement of almost all the tectonic plates on the planet. It really was an event of global significance. “
The team of scientists continues to work on the analysis of all the samples collected during the expedition, so it is expected that, in the coming years, new data will continue to be discovered about this fascinating and unknown continent.
