Zealandia Under Pacific Close To Recognition As Continent

Posted: Feb 17 2017, 3:30am CST | by , in News | Latest Science News

 

Zealandia under Pacific Close to Recognition as Continent
Simplified map of Earth’s tectonic plates and continents, including Zealandia. Continental shelf areas shown in pale colors. Large igneous province (LIP) submarine plateaus shown by blue dashed lines: AP—Agulhas Plateau; KP—Kerguelen Plateau; OJP—Ontong Java Plateau; MP—Manihiki Plateau; HP—Hikurangi Plateau. Selected microcontinents and continental fragments shown by black dotted lines: Md—Madagascar; Mt—Mauritia; D—Gulden Draak; T—East Tasman; G—Gilbert; B—Bollons; O—South Orkney. Hammer equal
 

Zealandia -- a lost continent submerged in the southwest Pacific -- is a step closer to being recognised, the authors of a new scientific paper have claimed.

A paper published in GSA Today, the journal of the Geological Society of America, contends that the vast, continuous expanse of continental crust, which centres on New Zealand, is distinct enough to constitute a separate continent, the Guardian reported.

The paper's authors argued that the incremental way in which it came to light goes to show that even "the large and the obvious in natural science can be overlooked".

Zealandia covers nearly 5 million sq. km, of which 94 per cent is under water, and encompasses not only New Zealand but also New Caledonia, Norfolk Island, the Lord Howe Island group and Elizabeth and Middleton reefs.

The area, about the same size as the Indian subcontinent, is believed to have broken away from Gondwana -- the immense landmass that once encompassed Australia -- and sank between 60 and 85 million years ago.

"This is a big piece of ground we're talking about, even if it is submerged," said Nick Mortimer, a New Zealand geologist who co-authored the paper.

Geologists have argued in favour of Zealandia being recognised as its own continent intermittently over the past 20 years.

Zealandia would be the world's seventh and smallest continent, after Eurasia, Africa, North America, South America, Antarctica, and Australia.

Paper Abstract:

A 4.9 Mkm2 region of the southwest Pacific Ocean is made up of continental crust. The region has elevated bathymetry relative to surrounding oceanic crust, diverse and silica-rich rocks, and relatively thick and low-velocity crustal structure. Its isolation from Australia and large area support its definition as a continent—Zealandia. Zealandia was formerly part of Gondwana. Today it is 94% submerged, mainly as a result of widespread Late Cretaceous crustal thinning preceding supercontinent breakup and consequent isostatic balance. The identification of Zealandia as a geological continent, rather than a collection of continental islands, fragments, and slices, more correctly represents the geology of this part of Earth. Zealandia provides a fresh context in which to investigate processes of continental rifting, thinning, and breakup.

Manuscript received 12 Sept. 2016; Revised manuscript received 19 Dec. 2016; Manuscript accepted 21 Dec. 2016. doi: 10.1130/GSATG321A.1

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<a href="/latest_stories/all/all/2" rel="author">Luigi Lugmayr</a>
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