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13

I don't recall this being considered a real 'mystery'. For decades after Tuzo Wilson's revolutionary Plate Tectonics the accepted explanation was of a change in direction in the plate motion over the mantle plume. I am pretty sure this was still the case when I read Plate Tectonics: How It Works (by Cox and Hart, Wilson's former students - I encourage you to ...


8

The nomenclature is confusing and recent studies have shown that among mid-ocean ridge basalts (generally called MORBs) that normal mid-ocean ridge basalts (NMORB) should reflect the statistically usual composition while enhanced MORB (EMORB) and depleted MORB (DMORB) should reflect end-members of the MORB population. Gale et. al 2013 proposes the use of ...


8

Yes, Iceland is an example of a hotspot overlying a plume. The plume has been imaged seismically, e.g., see the Science paper (Figure 3) by Montelli et al. (2004). It is available at http://www.sciencemag.org/content/303/5656/338 The 2015 paper you referred doesn't dispute that claim. All is says is that "The plume split off a sliver of continent from ...


5

Divergent boundaries occur at the boundary between plates. A divergent boundary is where two tectonic plates are actively being pushed apart. Divergent boundaries create rift valleys on land and eventually ridges on ocean floors, where hotter material wells up from the mantle, cools and form new crust. For example, the East African Rift Valley (a divergent ...


4

Don't be mislead by the subaerial part, it is actually a ridge on a large scale but neither the lava production rate nor erosion rates are constants. That leaves the ridge with higher and lower parts, as well as gaps. Furthermore reef building biocenoses change shape and appearance of the eroding volcanic edifices. Hawaiian (and other like for instance the ...


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