NEW Zealanders have long scoffed at suggestions of becoming Australia's seventh state but in a major shock on both sides of the Tasman, it turns out Kiwis and Kangaroos once could have got along fine if only the terra nullius had stayed united.
But about 75 million years ago, a mass of land broke away from Australia and started drifting east before subsiding beneath the sea.
Now an expedition led by the Australian National University will make the first scientific efforts to try to solve the mysteries of the underwater continent that was believed by some to have been discovered and named Zealandia just 22 years ago.
The drill ship JOIDES Resolution leaves Townsville on Friday for a two-month research voyage with up to 55 scientists on board.
Professor Neville Exon of the ANU Research School of Earth Sciences said the expedition would help scientists better understand the major changes in the global tectonic configuration that started about 53 million years ago as the "Ring of Fire" came into existence.
"Zealandia, including today's Lord Howe Rise, was largely part of Australia until 75 million years ago, when it started to break away and move to the north-east. That movement halted 53 million years ago," he said.
Zealandia covers 5 million square kilometres, is 94 per cent under water and extends from south of New Zealand northward to New Caledonia and west to the Kenn Plateau off Rockhampton.
However, there are some who say the submerged continent's existence had been known for nearly a century and the word Tasmantis was coined in 1919.
Zealandia was named by US geophysicist Bruce Luyendyk in 1995 and was not considered continent material until February last year when a team of international scientists declared satellite technology and gravity maps of the sea floor had shown Zealandia was a large, unified area to qualify as a continent.
JOIDES Resolution, part of the International Ocean Discovery Program, has impressive capabilities: in each drill hole, it can gather more than a kilometre of continuous cores of sediment or rock. The ship is 143 metres long with a drill tower 61 metres high, and it generally carries a crew of 50 in addition to scientists and technicians.
New Zealand co-chief scientist Professor Rupert Sutherland of Victoria University, Wellington, said the drill ship would collect five kilometres of sediment to discover how a region hundreds of kilometres east of Australia had behaved during the past 53 million years.
"The continental crust of Zealandia was thinned by stretching before it separated from Australia so that it lies lower than Australia," Professor Sutherland said.
"Zealandia's continental crust is thicker than the surrounding oceanic crust, and so it lies higher than that."
US co-chief scientist Professor Jerry Dickens, of Rice University, Texas, said the region was a vital area to study the changes in global climate and oceanography.
"As Australia moved north and the Tasman Sea developed, global circulation patterns changed and water depths over Zealandia fluctuated. This region was important in influencing global changes," he said.
Scientists will study the cores on board and onshore to address problems in fields such as climate and oceanographic history, extreme climates, sub-seafloor life, plate tectonics and earthquake-generating zones, and the dynamics of island arcs and ocean basins.
The expedition is scheduled to wind up in September when the ship docks in Hobart.
