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Not a Plate Boundary??

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If the Gakkel Ridge isn't the plate boundary between the NA and EA Plates, what then is it the plate boundary of? That other ridge is certainly not a plate of its own. Tmangray (talk) 19:11, 11 April 2008 (UTC)[reply]

Howdy - I can't find anything to document that the Lomonosov Ridge, oceanic crust of the Polar, Fletcher, and Canada Abyssal Plains, and Alpha Cordillera are NOT moving with the North America Plate - so, no further argument from me. Cheers Geologyguy (talk) 19:40, 11 April 2008 (UTC)[reply]
And I apologize for my tone in the edit...just a bit flummoxed. Tmangray (talk) 19:53, 11 April 2008 (UTC)[reply]
Well, then, I must apologize for quickly changing without verifying. Cheers Geologyguy (talk) 19:54, 11 April 2008 (UTC)[reply]
Others may misread Geo-guy's (intentional) double negative as i initially did; i now think he agrees that it is (at least) reasonable that GR may be the NA/EA plate boundary.
My own thot is that the motion of "the slowest spreading ridge on earth" may have been lost in the noise -- until it was measured between two ocean-bottom points maybe tens of km apart (or close to the zone of active extrusion, which AFAI can find out in WP may be well under a km wide), instead of between sub-arctic land points about 5000 km apart. Practicable land-based measurements would have had to measure about a part per million per year (even assuming having chosen a baseline at a substantial angle to the axis of the spreading zone), so AGAVE may have made the first statistically significant finding about the plates' relative status. (In contrast, St. John's to either Bantry Bay or A Coruña seems to be a much shorter distance! And the IIRC geophysically classic pair of Brazil and Dakar are still closer.)
--Jerzyt 06:22, 19 August 2009 (UTC)[reply]


Lead-section language

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In working on the horrid mess of passive voice and unnecessary repetition of nouns, i also changed

The axial valley of the ridge with an area greater than 10 km2 is covered with unconsolidated fragmented pyroclastics. This requires a ten fold increase in volatile pressures over that of normal mid-ocean ridge magmas.

in which the phrase "volatile pressures" would not be understood, except by readers with degrees in the physical sciences, as meaning anything like

the pressure, due to volatile substances that stay dissolved in magma as long as it is confined in the earth's mantle, which contributes to dispersing the magma as it escapes into the relatively weaker but still significant confinement by the pressure of the ocean depth in question

-- which is how my background knowledge suggests construing it. It might, however, be better worded (than my version at the next indent) by an oceanic geologist, or any editor with access to the paid-only Internet-access portion of the Nature (journal) article. And i note that brief, relevant quotations from that article, on this talk page for the purpose of facilitating discussion of its meaning by editors involved in paraphrasing it, would be the beau idéal of what the fair use provision calls "purposes such as ... scholarship[,] or research". Based on what i read on the Nature article's Web page, i replaced with

These suggest concentrations of volatile substances ten times those in the magmas of normal mid-ocean ridges.

In doing so, i relied on the relevant free portion of the Nature paper:

A pyroclastic deposit has never been observed on the sea floor below 3,000 m, presumably because the volatile content of mid-ocean-ridge basalts is generally too low to produce the gas fractions required for fragmenting a magma at such high hydrostatic pressure.

In particular, the near-weasel words "has never been observed" and "presumably" strongly suggest that "requires" is either a mis-paraphrase, or quotation out of context, from the journal article.
I also avoided the truly "bizarre" prospect of the use of robot submersibles by microbial communities.
--Jerzyt 06:22, 19 August 2009 (UTC)[reply]

added

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Put in Coords. (27.34.39.97 (talk) 11:46, 16 August 2012 (UTC))[reply]

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