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The SCIENCE and NATURE of plumes, jets and heat-pipes; publishing, promoting, and persistence of pet paradigms

Dev L Advocate

Friday, June 6, 2014

 

A note on references: The author uses Googlets, which are italicized, bracketed or highlighted phrases and key words. They can be regarded as simply part of the text or they can be copied and pasted into a search engine. In Wikipedia and in some electronic books, the highlighting of phrases can lead directly to a unique dry definition or reference. In the present case, they lead to a series of mostly relevant references. A short essay on the Origin and Evolution of the Earth can become a text-book and a semester course if one takes advantage of the infinite resources on the Web by employing TOE Googlets [copy and paste the italicized phrases into Google and ignore the impertinent results; e.g. Earth; Paradigms and Paradoxes]. A paradigm is like Plato’s cave; the Googlets sprinkled throughout the text can be considered as minor distractions or as a trail of crumbs that might show the path out of the cave!

Other references are embedded entries in the text such as [Nature 1973 plume] or given as long lists [Nature 244, 398–400 (1973); Evidence for mantle plumes? Nature 450, E15. 2007; Ian Jackson Nature 485, 51-52 (2012); Nature, 318, 145-149 (1985), 307, 114 (1984), 297 (5865), 391–393 (1982); lithosphere and flood basalts Nature 239, 42-43 [1971] etc. By searching on key word phrases, abbreviated references or Googlets, one can more easily connect the dots and discover that even in Science and Nature one can find evidence that the canonical models, and the underlying assumptions, that have dominated mantle geophysics and geochemistry for more than 40 years are implausible, unfalsifiable, unnecessary, and even “impossible”, violating the 2nd law of thermodynamics. The text is full of snippets that can either be taken as outrageous assertions or obvious truths, depending on one’s education, friends, funding sources and assumptions. Googlets will allow open-minded people to decide for themselves. The quickest way to get a feel for the controversy is to simply scroll down and read the retrieved snippets. This will at least expose the emperor as having no clothes. Of course, a deeper understanding is available to those who have time to open some of the documents.

It is also instructive to take a search string, such as finite frequency seismology debate andmantle plume and compare the results found onGoogle.com with those found on Nature.com and Sciencemag.com. Clearly, one must read and search outside of the influential prestige magazines to get a fair and balanced, or even accurate, view of mantle dynamics.

Zombie SCIENCE; silver bullets and coffin nails

Most scientists are too busy with their own specialty to pay much attention to developments in related areas. The weekly general science magazines become the main avenues for seismologists to learn about the views of geochemists and for petrologists to learn about tomography. These views are filtered through the editors and commentators and get picked up, reinterpreted, and widely distributed by the mass media. The so-called top elite prestige science journals therefore have a disproportionate influence on convention wisdom, funding and promotions. They become part of the infrastructure of a scientific paradigm. No editor will admit to having a bias or agenda and most do not. But the fragmentation of science has made the jobs of editors and reviewers complex. A simple test for contemporary bias is to insert a search string such as [hawaii samoa iceland finite frequency controversy] into sciencemag.org and then compare the recent hits with earlier ones and with the same search string inserted into Google.com. When searching Nature.org and Sciencemag.org, rather than Google.org, with [hawaii samoa iceland hotspot controversy] one gets the impression that there is no controversy or that it has been settled. The terms “Hawaiian plume”, “Azores plume” and so on are commonly used instead of simply “Hawaii” and “Azores”. Volcanic chains are referred to as hotspot tracks. The view of Science magazine of the canonical model of mantle geochemistry and geodynamics is well summarized by items retrieved from the site Sciencemag.org with the search strings [mantle plume; debates DePaolo Hofmann Hart Tackley Kerr]. Compare the results with the same searches on Google.com.

Science magazine [kerr science plumes], has documented the plume debate, and in April 2013 essentially declared the debate to be over [DePaolo Manga plume science; hofmann hart plume science; Tackley, if plumes are not the answer, what is?; Richard Kerr plume science]. The title of some of the commentaries are; The Great African Plume emerges as a tectonic player, From Earth’s core to African oil, Mantle plumes both tall and short, Rising plumes in Earth’s mantle, Sea-floor study gives plumes from the deep mantle a boost, and finally, The deep Earth machine is coming together (rising plumes connect hotspots and diamond pipes to the bottom of the mantle). Once something wrong is published in Science as a fact, it can take years to clean up the mess [finite frequency seismology debate].

Although most of the evidence for the “Plate”, top-down, layered mantle convection, hot ambient mantle models and shallow sources of “hotspot” magmas appears elsewhere, one can find strong evidence against the canonical model even on the pages of Science;

An Ancient Os Isotopic Reservoir, Science, 296, 516-518, 2002; Top-down tectonics? Science 293, 2016–2018; The Rise and Fall of a Great Idea (2008), Science, 319, 418-419; 1999. Mantle values of thermal conductivity and the geotherm from phonon lifetimes. Science 283, 1699–1706; Low Core-Mantle Boundary Temperature Inferred from the Solidus of Pyrolite, Science, 2014, 343, 522-525; Waveform Tomography Reveals Channeled Flow at the Base of the Oceanic Asthenosphere, Science, 11, 342, 227-230, 2013.

None of these papers directly challenge the plume conjecture but when taken all together, they show that mantle plumes are unnecessary, the underlying assumptions are invalid and all predictions have failed. Multiple models for plumes near Hawaii have been published in Science, all different [Hawaii tomography mantle (images)]. Together, they comprise powerful evidence against the paradigm.

Searching NATURE for the answer

Nature magazine assumes the existence of mantle plumes is a fact [plumes persevere geoscience]. Top-down and plate-tectonic mechanisms related to stress and fractures are not discussed. [Search nature.com with the keyword string Hawaii Iceland geology plume.]The same search on Google.comwill return a broader inventory of possibilitiesas well as problems with the plume hypothesis.

Although Nature Magazine is part of the plume paradigm industry it has published articles that are nominally unrelated to the model but, when taken together, undermine it. If paradigms are well-defended, walled cities, these would be examples of Trojan horses. Articles published in Nature over the years show that mantle plumes are unnecessary and are physically implausible, e.g.,Marion Rise. Nature 494, 195-200 [2013]; Melt-rich channel observed at the lithosphere-asthenosphere boundary. Nature 495, 356359 (2013); Heat-pipe Earth, Nature, 501, 501–505, doi:10.1038/nature12473, 2013; The dynamics of melt and shear localization in partially molten aggregates. Shear-driven Nature 442, 676-679; 2006; Ponded melt at the boundary between the lithosphere and asthenosphere Nature Geoscience (2013), 6, 1014-1044; Hotspots, polar wander, Mesozoic convection and the geoid. Nature 297 (5865), 391–393 (1982).

Transition region of the Earth’s upper mantle, Nature 320, 321-328; 1986.; Hotspot magmas can form by fractionation and contamination of mid-ocean ridge basalts, Nature, 318, 145-149 (1985); Chemical inhomogeneity of mantle above 670 km transition: Nature, v. 307, no. 5947, p. 114 (1984); Thermal plumes in the Earth's mantle. Nature 244, 398–400 (1973); Evidence for mantle plumes? Nature 450, E15. 2007; Ian Jackson Nature 485, 51-52 (2012); Nature, 318, 145-149 (1985), 307, 114 (1984), 297 (5865), 391–393 (1982); lithosphere and flood basalts Nature 239, 42-43 [1971]

The above references answer the question posed by Paul Tackley if plumes are not the answer, what is? The anisotropy and heterogeneity of the outer 200 km of the mantle can accounts for the relative travel-time delays of teleseismic waves that have been attributed to deep mantle plumes. The thickness of the crust, the composition of basalts, heat-flow, seafloor bathymetry and seismic tomography support the view that buoyant refractory shallow mantle and underplated melts underlie the swells in the ocean basins. The seismic structure of the mantle under swells is similar to the mantle imaged under some segments of the mid-ocean ridge system and the basalts erupted at oceanic plateaus is more similar to basalts erupted at ridges than erupted in places where contamination by a thick boundary layer is plausible.

Basic tenets of the plate model, derived from seismology, mass balance and mineral physics, is that the lower mantle may be rich in silica and is too dense to rise into the shallow mantle, and that slabs at 650 km depth trigger downwellings in the underlying mantle by thermal coupling. Travel-time tomography ignores the background model and smears out upper mantle features. It is cartoons based on these models that appear in most publications [mantle plumes (images)]. None of these images satisfies the global seismic database, or meets the requirements of an isolated, self-compressed planet with self-organized convection.

The effects of wavefront healing show that plumes are invisible, and establish that claimed deep mantle plumes are artefacts. The breadth of regions labeled “plume” or “plume-like” actually confirms the passive nature of these features and are consistent with generalized top-down 3-D plate tectonics. Passive updrafts not only feed ridges, but, after interacting with the boundary layer, may also be involved in intraplate volcanism [hot spot magmas contamination fractionation]. Heat-pipes may have existed during accretion of the Earth but were soon snuffed out by normal convection, and plate tectonics [moore heat-pipe Nature]. The effects of compression, secular cooling, and chemical stratification [perovskitite lower mantle Nature 485] eliminate heat-pipes as an observational fact or a viable physical theory for present-day Earth. Plate tectonics, stresses in plates, the top-down requirement of a cooling isolated planet, and Archimedes principle, are more relevant than pots on stoves and thunderheads.

6th June, 2014

last updated 2nd May, 2014

MantlePlumes.org