Virginia Volcanoes Linked to East Atlantic Islands
The youngest volcanoes on the East Coast share an unusual geological link with islands on the opposite side of the Atlantic Ocean, a new study reports.
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“Geologist [I'm Climate Change]”
Since: Mar 07
#2 Apr 30, 2014
Hotspots run in several flavours.
The Yellowstone & hawaiian hotspots have a deep origin from the core mantle boundary & have an emphasis on heat rather than spreading.
The Iceland, Azores, & Galapagos hotspots have more emphasis on spreading rather than heat & appear to have an origin from higher in the mantle with less core/mantle boundary component.
The pacific ocean island volcanoes appear to be upwelling within the mantle & accumulate magma in a disc @ the base of the crust. The volcano appears as a result of a fracture in the crust above the disc. Similar hotspots are the Cape verde islands & the Reunion hotspot. A similar, more active version appears to result in the Canary islands.
This may be millions of years after the disc accumulates.
The Virginia volcanoes are from a hotspot of this type & the hotspot that formed them now sits in the middle of the North American plate in the Atlantic & is responsible for a seamount chain in the Atlantic.
The long residence time & the base of the crust after the passage of the hotspot results in cooling of the accumulated magma and the crystallisation of high temperature minerals. The result is the eruption of low temperature magmas of Alkali basalt through phonolite to foidite.
The American E coast volcanoes erupted from high points in the underlying crust & are in positions well away from the hostspot track. The mechanism resembles bubbles under an ice crust, the magma may migrate hundreds of km from the hotspot before eventually erupting.
The African hotspot volcanoes are exactly the same (such as Tibesti, & Darfur) resulting in random scattering of volcanoes unrelated to continental drift over the hotspot.
Have a nice day: Ag
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