The Mantle Plume Myth

Some ideas are very attractive, and quickly capture people’s imagination.

One such idea is that there are mantle plumes deep in the Earth, up which superheated molten rock ascends, melting through the lithosphere at the surface of the Earth, and creating volcanoes. And as the plates of the lithosphere move over a fixed mantle plume in the Pacific ocean, the volcanic Hawaiian islands are formed in a chain leading away from the mantle plume.

This idea appeared in about 1970, shortly after the idea of plate tectonics took hold, and it seems it’s now taught in geology courses along with plate tectonics. It’s become part of the science of geology.

But it seems that some people think the idea is physically implausible, and in fact a complete myth:

There is not even any agreement about the existence, or location, of features under Hawaii, the poster child of the plume myth. The original, now largely abandoned, definition of ‘plumes’ involved self-driven, strongly buoyant, narrow upwellings from fixed points at great depth, which drove plate tectonics, kept ridges open and provided much of mantle heat-flow.

And a very long-running myth:

The plume debate is now one of the longest standing scientific controversies in the Earth sciences, having lasted longer than the age of the Earth, crustal growth and fixity-vs-drift controversies.

Some questions come to mind, that don’t seem to have been answered. If there’s a continuous plume of superheated molten rock flowing up the plume, why aren’t the volcanoes in the Hawaiian islands in continuous eruption, rather than intermittent eruption? And why isn’t there one long narrow island extending away from the mantle plume, rather than a series of islands? Is the plume intermittent?  And is it really thermally plausible for there to be what is effectively a huge blowtorch burning its way through tens of kilometres of solid rock to the surface? Wouldn’t the mantle plume widen as it rose, just like the plume of smoke above a cigarette (left)?

Once the plume idea took hold, the plumes began to multiply in numbers, and behave in all sorts of ways.

A simple, elegant, satisfyingly neat, concise, falsifiable hypothesis has become a complicated, awkward, messy, unfalsifiable monster that refuses to lie down and die. According to the more cynical philosophers of science, failed hypotheses, heaped high with anomalies, paradoxes and auxiliary conjectures, are perpetuated by repetition and self-referencing because too many adherents have invested their careers in them. Although many scientists have moved on plumeology remains entrenched conventional wisdom, supported by the publishing industry, with alternative opinions discouraged and made to jump a higher bar. Young scientists who should be encouraged to question dogma are kept in line via hiring, promotion, grant proposal and publication decisions. Zombie research programs defy burial.

One reason for the persistence of the idea of mantle plumes is that nobody seems to have come up with a better explanation for the Hawaiian island chain.

Another similarly beautifully simple idea, that quickly captured people’s imaginations, is that Smoking Causes Lung Cancer. The rising incidence of lung cancer was the result of the rising prevalence of cigarette smoking, which entails inhaling hot, toxic, carcinogenic smoke into the lungs. Wasn’t it obvious? What other explanation was there? More or less overnight, the idea became a new medical dogma, driving a crusade against smoking.

But this simple idea also became a complicated, awkward, messy, unfalsifiable monster. Initially it was just new-fangled cigarettes which were blamed for the lung cancer epidemic, but gradually all tobacco products were blamed for it. So why hadn’t there been a lung cancer epidemic before cigarettes were popularised in the early 20th century? And why is the lung cancer epidemic continuing despite smoking prevalence having fallen drastically over the past 70 years? Why are never-smokers getting lung cancer? What is the precise mechanism by which tobacco smoke (and tobacco smoke alone) causes lung cancer? Why haven’t animal studies been able to produce lung cancer? Why do some smokers get lung cancer, but not others? Aren’t there lots of other possible explanations for the cancer epidemic, including radioactive fallout, HPV, genetic predisposition, and diesel fumes?

Isn’t the cigarette hypothesis another failed hypothesis, heaped high with anomalies, paradoxes and auxiliary conjectures, which is being perpetuated by repetition and self-referencing because too many adherents have invested their careers in it?

And isn’t the same true of the global warming scare? It’s another very simple idea, which is that carbon dioxide in the atmosphere absorbs long wave radiation, causing the atmosphere to warm. It’s so simple that even poor little Greta Thunberg can grasp it.

Perhaps it was ever thus. New ideas of great power and simplicity periodically sweep the world, and launch crusades that drive all before them – until it gradually emerges that these new ideas were themselves just new illusions, new myths.

About Frank Davis

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4 Responses to The Mantle Plume Myth

  1. That’s pretty interesting that there is controversy surrounding this. I know that there are a lot of people still trying to explain it/understand it, arguing like mad about it, but had no idea there was a contingency that thinks mantle plumes are pure myth. Makes me wonder what these same people think about volcanic “hotspots” like Yellowstone/Iceland, what they think about lava lakes, and what they think about the Mid-Atlantic ridge, black smokers/thermal vents, undersea volcanoes and the like. Not to mention places like Jupiter’s moon Io and what they think is going on there, plus our Sun/Sol and places we’ve not yet mapped/figured out how to map where sunspots might be more prevalent, more prone to x-ray bursts/solar flares/coronal mass ejections, etc..

    And to be fair-ish, Kilauea in Hawaii has been continuously erupting for quite a while. Also quite a few other volcanic places that appear to be somewhat “angry” all the time. Makes me wonder what qualifies as “continuously erupting”, and where this erupting needs to take place/what constitutes an eruption and where. If a large amount of energy is tossed out of the inner-core at just the right spot, it makes it all the way to the mantle at or near one of these mantle plumes, but doesn’t have the energy to make it all the way out of the crust/break the surface and spew out into the atmosphere, then does an about face and returns back towards the core, does that count as an eruption? Maybe volcanologists, geologist, seismologists and other earth sciences people need to look to space flight types (parabolic, orbital, etc) to maybe better classify the movement of energy/energies and mass/matter as it pertains to volcanic activity? Coronal loops + when they break and when they don’t + the “pockets” that coronal loops create? Or is too much of a stretch to think that coronal loops somewhat emulate maybe what is going on with respect to “hotspots”, mantle plumes, lava lakes, active/previously inactive volcanoes + when/where/why they do/do not erupt?

    I dunno either. :-D

    ^The Dead Milkmen-Born to love volcanos^

    Just appears to be a lot more going on than just/only “up and out” as it pertains to volcanoes. The whole damn planet and everything else is always spinning, not to mention that our lack of understanding of both our atmosphere and hydrosphere seems to be quite poor. Especially what roles they and their behaviors play with respect to volcanic, seismic and/or other geologic types of activity. For example, there are currently 6 tropical storms active at the same time. Surely our planet’s geological goings on in it’s guts have something to do with that.

    Just found this…

    Six underwater volcanoes found hiding in plain sight

    I can’t read that article, but it’s recent, and it looks interesting. Maybe you or someone else can read it. :-)

    ^MS MR – Hurricane (Official Video)^

    The only constant on this planet, and even everywhere else, seems to be change. I don’t know math really, but I did some digging, found this.

    10 Equations a Geology student should know

    Maybe this is my lack of understanding of math, how it works, and why certain concepts are omitted from formal/well-developed equations, but I don’t see Delta(Δ) in any of those. I don’t see time accounted for either.
    Q: Why is there no scientific symbol for time?
    A: Or is there one, and I just don’t know about it.
    Just seems like time/change are always omitted and left to the conjectures of interested parties.

    Anyway, thanks for the read Frank. Interesting stuff.

    ^CHVRCHES – The Mother We Share^

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