Talk:Island arc

message: Not happy about the phrase "Weathering and erosion of these volcanic rocks produce black-green beaches composed of olivine sand eroded from the volcanic cones."
While some calc-alkaline volcanics are oliving-phyric, it's not particularly common. Black-sand beaches are more often composed of ilmenite and magnetite, with olivine a relatively minor component.
A Karley 12:45, 10 August 2006 (UTC)
thread_title:  Black sand beaches 

message: After editing both of these articles today, it seems clear to me that this one should be merged into the other.  All island arcs are volcanic arcs, so this article is just a subset of the other.  There is already major overlap in content in the two articles, so this was an easy decision to make.  Better to have one nicer, more comprehensive article than just leave these two as they are now. --Seattle Skier (talk) 01:16, 13 April 2007 (UTC)
thread_title: Merging [[Island arc]] into [[Volcanic arc]]

message: 'This is a consequence of the geometry of the spherical plate crumpling along a line on a spherical surface.' This sentence appears to have no content: it states that the arcuate shape is a consequence of two plates meeting. (Also 'curve' might be better than 'line'.)
The thought behind the above quote could be that a flat plane intersects a sphere in an arc. This idea is a nice one, but doesn't fit well with observation. On the spur of the the moment, I can come up with perhaps better hypotheses. Could someone provide several references to a current theory as to why arcs are arced, and what the varying geometry of arcs consequently tells geologists?
If current plate tectonics provides no explanation, then some big change or addition to current tectonic theory is awaiting: one should perhaps not ignore the arcs as trivial and let the reader think that current plate tectonic theory explains them well.
In short, plate tectonics explains the 'islands' and 'volcanic', but not the 'arcs'. Perhaps this should be made clear. Geologist (talk) 20:49, 23 October 2009 (UTC)
thread_title: Why are volcanic arcs arced?

message: I'm under the impression that Japan is actually a piece of the mainland pulled off as the ongoing subduction stretches the riding plate, and not really an island arc per se.  —Preceding unsigned comment added by 71.135.102.61 (talk) 04:54, 24 March 2010 (UTC)
thread_title:  Japan 

message: The section on oceanic trenches asserts that trenches are the result of a "gravitational pull" effect: 'This trench is created by the gravitational pull of the relatively dense subducting plate pulling the leading edge of the plate downward.' I doubt, however, that this actually relates to the force of gravity. I would suppose that it relates more to the rigidity of the lithosphere, with the subducted edge pulling down the attached ocean floor nearby due to tension. Will someone more knowledgeable than I confirm this, or add references? JackS333 (talk) 20:33, 9 May 2010 (UTC)
thread_title:  Gravitational Pull? 

message: I have added a "{missing}" tag and included the info I think is missing. Not all island arcs or chains are related to subduction, and the current article does not explain the existence of intratectonic chains such as the Hawaiian Islands.
77.165.250.227 (talk) 14:04, 22 May 2015 (UTC)
replies: text: Hotspot volcanic chains are formed completely differently. Volcanic arcs result from specific mechanisms of formation, and are their own separate feature. — Gorthian (talk) 20:40, 6 June 2016 (UTC)
thread_title:  Hotspots 

message: The article says It is now believed that water acts as the primary agent that drives partial melting beneath arcs. It has been shown that the amount of water present in the down-going slab is related to the melting temperature of the mantle., which sounds fine but then goes on to say The greater the amount of water present, the more the melting temperature of the mantle is reduced. This is confusing. If water reduces melting then how can it be the primary driver?  — Preceding unsigned comment added by 85.211.226.224 (talk) 15:34, 3 February 2019 (UTC)
thread_title:  Driver of melting beneath arcs 

message: Isn't Hawaii a Volcanic Arc? The Hawaiian Arc is very large, and it extends, completely engulfing the Midway Arc. Even the wikipedia page for Hawaii shows that Midway Islands are, in fact, part of the Hawaiian arc.
ConlangingMango (talk) 11:51, 28 July 2020 (UTC)
thread_title:  Hawaii