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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 ...

1

If I look at Google Earth imagery, it is not just the Hawaii Emperor Seamount Chain, but also those of Louisville Hotspot Chain and Society or Pitcairn Hotspot Chains show a slight bend , the Louisville Chain shows a more 'graceful' bend like a gradual 30° bend and Society or Pitcairn somewhere like 40° bend and the Hawaii emperor seamount chain shows a more ...

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