Talk:Zealandia

outline

It would be much more clear to the average reader where/what exactly is considered Zealandia if that area were outlined on the map. ⇔ ChristTrekker 15:19, 28 September 2007 (UTC)

Thanks to whomever added Zealandia-Continent map en.svg. ⇔ ChristTrekker 14:36, 4 March 2008 (UTC)

submerged continent

on this article here it says that submerged continents are a physical impossibility. but this article says that Zealandia is a submerged continent. what is the correct view here? —Preceding unsigned comment added by 124.43.230.33 (talk) 10:36, 17 October 2007 (UTC)

Well it says that it broke away and then sank. --Savre 21:25, 17 October 2007 (UTC)

It's just a matter of linguistics. It can't 'sink' since it hasn't got water as its foundation, but it can be submerged by it if water levels rise... So it's not 'sinking' in the nautical term of the word. —Preceding unsigned comment added by 193.190.253.146 (talk • contribs)

It's possible that it could be stretched out, and a thinner continent would ride lower in the crust, possibly below sea level. The English Channel is submerged continent, as are continental shelves all over the world. But a continent wouldn't sink to the level of oceanic crust; there would be remains like Zealandia. kwami 22:55, 17 October 2007 (UTC)

The Lemuria article has since been fixed. -- Avenue (talk) 09:31, 1 June 2008 (UTC)

As far as i'm aware it is just quite low lying, and only present as a continet during the middle of ice ages. —Preceding unsigned comment added by 121.216.35.159 (talk • contribs)

The portion that was above sea level in the depths of the last ice age was still only a small proportion of the whole. Sea level then was about 130 m lower (see our article on sea level rise), but much of Zealandia lies 500-1500 m below the sea. -- Avenue (talk) 09:31, 1 June 2008 (UTC)

I'm wondering why the above paragraph (or something like it) isn't in the article---that was the first thing I wanted to know, namely, how deep is he submerged portion, and how much was exposed during ice ages? Could a mention of that (as quantitative and precise as possible) be added? I'm not an expert, so I'll leave it to you folks. Thanks. -- Spireguy (talk) 22:10, 26 March 2009 (UTC)

Not a Continent?

I question the assertion that Zealandia is actually a continent, i.e. formed of continental crust. The technical papers I've seen indicate that it is no more than an oceanic plateau, made up of crustal material that is intermediate between oceanic crust and true continental crust. Owing to its density, it's unlikely that any significant part of it ever extended above sea level. New Zealand itself is indeed comprised of fully continental crust, unlike this Zealandia. Tmangray (talk) 05:05, 11 April 2008 (UTC)

Please tell us which technical papers you're referring to, so we can incorporate or rebut your interpretation of them. There is some high-standing oceanic crust around Zealandia, but Zealandia itself is continental - see e.g. this map. Its rocks have similar density to other continental areas, but are generally much thinner; that's why most of it is now submerged. -- Avenue (talk) 11:13, 11 April 2008 (UTC)

I think the real crux of my contention is what this article is claiming to be the extent of the continent. The Hikurangi Plateau, for example, is not continental crust, but a large igneous province, an oceanic plateau, no granite in sight. Am I wrong? Tmangray (talk) 21:16, 11 April 2008 (UTC)

I think you're right, about the Hikurangi Plateau at least. The source cited following that sentence (Mortimer, 2006) includes a map that clearly excludes the plateau. I'll remove that claim from the article. The Louisiade Plateau and Mellish Rise also look doubtful. -- Avenue (talk) 21:49, 11 April 2008 (UTC)

The LP and MR are both specifically included. As for the HP, that could simply be a defect in coloring the map, so it would be good to have confirmation. kwami (talk) 23:08, 11 April 2008 (UTC)

Why are they included? The Louisiade Plateau is not granitic, but is another oceanic plateau. Examination of plate reconstruction maps shows that this Zealandia is actually a narrow ridge-like structure, probably indicating that it is a terrane, not a continent, a former island arc. (By that definition, Baja California and everything granitic west of the San Andreas is a "continent".) These maps do not show any of the oceanic plateaus claimed. None of these are granitic. Unless you can show otherwise, they should not be included. Tmangray (talk) 04:08, 12 April 2008 (UTC)

The only undersea plateau that appears granitic is the Campbell Plateau, and it is specifically not referred to as an oceanic plateau or large igneous province, while most of the others are. Tmangray (talk) 04:20, 12 April 2008 (UTC)

Which plate reconstruction maps are you looking at? There is one in Mortimer's paper (Figure 3), and it clearly shows the Louisiade Plateau as part of Gondwana, not a separate island arc.

There seem to be two elements to your argument, which I think are separate issues: whether these areas consist of continental crust, and whether Zealandia is a "continent". On the second issue, I have seen it described as a continent, or as a microcontinent. Our article mentions both terms. Zealandia does not contain a craton, but it is certainly more than a terrane; it contains several (there are eight just in onshore New Zealand). -- Avenue (talk) 04:56, 12 April 2008 (UTC)

I don't know what that map is re:Louisiade, but I find no mention of granite; and I find mention of it as a large igneous (and basaltic) oceanic plateau caused by a hot spot, not a granite outcropping. As for the continent-terrane matter: that there is no craton is decisive. I see no distinction between this Zealandia fragment and any other terrane of continental crust. As with other terranes, it has no plate of its own, but is part of plates which include other continental crust as well as oceanic crust. Tmangray (talk) 06:38, 12 April 2008 (UTC)

Please tell us where you're finding these mentions, indications, etc. And where did you hear that a continent must have a plate of its own? I was probably too careless above about the absence of a craton, sorry. There is none exposed in onshore New Zealand, but there could be one elsewhere in Zealandia. See for example these slides by Chris Adams, a geologist at GNS; on the last slide, he refers to early Cambrian rocks found on Campbell Island, asking if they are "a tantalising glimpse of Zealandia’s cratonic core?" -- Avenue (talk) 10:36, 12 April 2008 (UTC)

Zealandia is made of continential crust. If you look at its western portion you will see it fits with the eastern coast of Australia; there used to be a mid-ocean ridge between Australia and Zealandia so it's pretty clear it used to be part of Australia, which is made of continential crust. Therefor I consider Zealandia a continent.

I think that's why Zealandia dosen't have much of a craton because much of its craton forms Australia, which was split apart from the ancient mid-ocean ridge. A similar formation is occuring in Antarctica; one part of the continent is non-cratonic and the other is cratonic with the West Antarctic Rift separating the two of them. Continents do contain volcanic rock and not just continential rock; much of the coast of Canada is made of volcanic rock from when ancient island arcs collided and fused onto North America; see the Wrangellia Terrane for example which is volcanic and seems to form part of the North American continent. A few hotspots are thought to underlie Zealandia which probably responsible for the volcanic rocks. Black Tusk 19:23, 12 April 2008 (UTC)

This paper by Gaina et al is relevant. It focusses on the opening of the Tasman Sea, and thus ignores parts of Zealandia north of the Chesterfield Plateau, south of the Challeger Plateau, and east of the Lord Howe Ridge. But within those bounds, it confirms that all the regions our article claims are part of Zealandia are blocks of continental crust: the Chesterfield Plateau, Dampier Ridge, Gilbert Seamount and of course the Lord Howe Ridge (including the Challeger Plateau). -- Avenue (talk) 01:32, 13 April 2008 (UTC)

Continent is not defined in matters of geology. If that would be so, India would also consider to be a separate continent. Avenue's argument in the beginning of the section requesting a technical paper is outrages. How about to take basic geography course, instead of jumping in with such requests. Aleksandr Grigoryev (talk) 23:32, 14 November 2014 (UTC)

Craton?

The microcontinent article says that Zeelandia contains a craton, this article should mention the continental core. 76.66.202.139 (talk) 14:53, 5 May 2009 (UTC)

As far as I know, this hasn't been confirmed yet, although it seems a natural guess given what is known of the parts of Antarctica that neighboured the southern parts of Zealandia - see e.g. this extended abstract. So I think the statement in the microcontinent article was a bit too strong. I agree it would be good to mention this; the whole Geology section needs a lot of expansion. -- Avenue (talk) 17:07, 5 May 2009 (UTC)

Tasmantis?!

The German Wikipedia mentions that "Tasmantis" is an alternative name for Zealandia. Does anybody know anything about that? Kelisi (talk) 17:17, 25 June 2016 (UTC)

Requested move 17 February 2017

• Zealandia (continent) → Zealandia
• Zealandia → Zealandia (disambiguation)

– WP:Primary topic. Similar to Africa, Americas, Antarctica, Asia, Australia, and Æurope. Out of all similar named topics, the proposed continent has the most significance in terms of science, geography and history. BBC, (The Guardian) Shhhhwwww!! (talk) 17:41, 17 February 2017 (UTC)

This is a relatively unknown continent. Zealandia (personification) may be a better candidate. Ruslik_Zero 20:40, 17 February 2017 (UTC)

• Oppose. No/not enough evidence presented that this subject represents a strong historic use of the term. Also, the subject of this article was recently in the news, meaning that this move request probably represents a form of WP:RECENTISM. Steel1943 (talk) 21:20, 17 February 2017 (UTC)

Classification as a continent

The text in this section says that the Geological Society of America has "stated" that Zealandia was a continent. To me, it's more correct to say that they published in their journal an article putting forward (again) the case for Zealandia to be classified a continent. VirtualDave (talk) 23:33, 17 February 2017 (UTC)