“Mantle plumes have never had a sound physical or logical basis,”
This week the geological and science communities have been a buzz after Pro Don Anderson released a paper rebuffing the idea of mantle plumes, an idea that has been a pillar of volcanology for years.
In the broadest of senses, there are three ways in which volcanoes form; at constructive tectonic plate boundaries (where plates are moving away from each other), at subduction zones (oceanic crust is pushed under continental crust at plate boundaries) and at hot spots caused by the illusive mantle plume.
Some of the world most active volcanic areas such as Hawaii and Iceland are attributed to hot spots. As the mantle plume is in a fixed location, plate motion above the plume creates chains of volcanic islands which have helped us trace the motion and speed of the tectonic plates. The Emperor and Hawaiian island chains are a beautiful example of this in the Pacific Ocean and are attributed to the Hawaiian Plume currently believed to be positioned under Kilauea.
But the reasoning behind these islands may be about to change. The team comprised of scientists from Caltech and the University of Miami and Florida suggests that new seimology data indicates that mantle plumes do not exist. Instead they propose that these hot spots are “the result of normal broad-scale convection and plate tectonics.” It is believed that convection with in the mantle, as suggested by Archimedes’ principle and the second law of thermodynamics, is characterised by narrow downwellings and broad updrafts.
Despite the hubbub the paper publish in The Proceedings of the National Academy of Science has caused, this is not a new argument. Lord Kelvin actually proposed similar theories back in the 19th century. Although he is considered a forefather of thermodynamics, much of this geological ideas where thrown out as he did not take in to account radioactive decay as a source of internal heating when looking at the cooling processed of the Earths interior (mainly as this was not known about to many years later).
The inner workings of the Earth are probably not going to be fully know for years to come, we are learning more and more with ever eruption and earthquake. As always as soon as more solid evidence is presented I shall update, as for now I am keeping an open mind.
Figure 1. http://www.mtu.edu/research/archives/magazine/2011/stories/great-dying/ Accessed 12.09.14
Figure 2. https://answersingenesis.org/geology/plate-tectonics/hawaiis-volcanic-origins-instant-paradise/ Accessed 12.09.14