Monday, July 18, 2011

[Geology2] Re: Volcano Activity - Iceland ...Not due to a "mantle plume"

--- In geology2@yahoogroups.com, Kim Noyes <kimnoyes@...> wrote:
>
> It's also probably/nearly certainly a Hot Spot/Mantle Plume ...

Hotspot iffy and "mantle plume" afraid not and none associated with the mid-oceanic ridge of the Atlantic ocean even though much of the magma is derived from the mantle. The last "active" mantle plume in the Atlantic basin,( and this is a debated topic amongst earth scientist if it was in fact a mantle plume), formed the island of Bermuda --as a short-lived, last sputter of a minor plume which has arose mid-North American Plate and traveled deeply under the Appalachian chain during the Cretaceous. Iceland has the happenstance and owes its existence to the mid-oceanic rift and past lower sea-levels. Iceland is one of the few spots on earth where a divergent boundary lies above sea level.

We there a "mantle plume" under Iceland there would be highly mafic( vs felsic) lava like what is found in Hawaii. Instead, the Icelandic lava has a high component of hydrated crustal rock in the melt leading to the high ash ryolitic-trending eruptions we see today.

Eman

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