I concur with Milidragovic et al. that water plays and important if not principal role in generation of high-Mg mafic and ultramafic melts. I think water is important not only in arc settings, but also flood basalts could not be generataed without this agent.–Alexei Ivanov

Manuel Curzi, University of Rome, provides the results of a natural laboratory experiment to demonstrate the development of plumes…

Click on me

Dear WM, Although the paper "Burov, E. & T Gerya, Asymmetric three-dimensional topography over mantle plumes, Nature 513, 85–89 (04 September 2014) doi:10.1038/nature13703" purports to show that plumes can break up continents if the continent is pre-weakened by plate tectonic forces, what it actually shows is that if one artificially inserts a 200 km sphere below the continent with an excess temperature of 200-600°C then one can break a pre-weakened continent. The 200-km sphere appears out of nowhere, as a deus ex machina. The same method was used by Cordery et al to obtain melting under thick plates.–Don Anderson

Dear WM, It is curious that the same tomographic features have been interpreted in completely different ways. Faster than average seismic wave-speeds in the TZ have been considered to indicate ancient subducted slabs (Piromallo & Morelli, 2003; Handy et al., 2010). The same features, on the other hand, have also been interpreted as a volatile-free mantle plume head trapped in the TZ (Lavecchia & Bell, 2012; Bell et al., 2013).– Michele Lustrino

Discussion of Dehydration Melting

Discussion of Heat

Dear WM, Some website readers might find this quote amusing. Tozer (1973) objected to the use of the word "plume" because of prior usage and connotations. However, the various definitions of "plume" and its antecedents in French, Latin, and German seem to provide enough flexibility to describe the phenomenon, its implications, and its raison d'être on the one hand and its inventors, supporters, and detractors on the other: Plume (English, from French and Latin, pluma) — a feather, a long handsome feature, a token of honor or prowess; a prize; to pride or congratulate; to preen. Plombe (Germanic) — a plug. Plombe (Old English from West Germanic) — something especially desirable, as a good position; panache (French) — trail, stripe, swagger; fumée (French) — smoke, fumes, steam; fumer (verb) — to fume, to dung, to manure; plumitif (familiar) — scribbler, pen-pusher.–Don Anderson

Dear WM, I recently came across the paper by Don Anderson in the Australian Journal of Earth Sciences "The persistent mantle plume myth". It is an informative, entertaining and devastatingly logical demolition of the plume 'hypothesis'. The author provides a cogent summary of what is wrong with the physics of plumes, as well as delving into the philosophical and psychological aspects of the plume story. In the almost indiscriminate invocation of plumes in many LIP and ore-deposit studies, plumes appear to have the same role as the Joker in a pack of cards: something that can be pulled out to trump any other card (hypothesis). Probably one of the most maddening aspects to plumes is the apparent lack of agreed upon criteria that can be used to test the model and its alternatives. For example, magmatism related to a plume should be an intense, very short-lived event. Apparently. Unless of course the magmatic event is prolonged, in which case the magmatism may be related to a cluster of plumes or a superplume! It is this polycephalic aspect to the plume story (in more ways than one) that raises the most questions about its legitimacy as a hypothesis.

Don Anderson's paper is also notable for its reference to various plume models published in some of the most elite journals, such as Science and Nature. Like others I pretty much gave up on those journals some years ago, finding them speculative and unhelpful to progress. Unfortunately, many still seem to regard papers in these journals as gospel, rather than somewhat subjective and unreliable material at the "frontier of science" that has been made widely available.–Steve Sheppard

Dear WM, This recent paper published by Mallik & Dasgupta concludes "mantle potential temperatures of 1330-1350°C appear sufficient to produce high-MgO, primitive basanite-nephelinite if carbonated eclogite melt and peridotite interaction is taken into account.".

This is more evidence that the geochemistry of mafic Mg-rich alkaline rocks can be explained with "normal" temperature, simply assuming a non-pyrolitic mantle source.–Michele Lustrino

Dear WM, Regarding the rapid eruption rates in flood basalts, I offer the following comment. Megacryst zircons from kimberlites record a range of ages from approximately the date of actual kimberlite eruption to about 5-10 Ma earlier than eruption (and sometimes more) (Data in Moore et al, 2008, EPSL 268:151-164, Fig.1). I am aware of unpublished data which shows the same relationship. Megacryst suites from individual kimberlites apparently crystallize isobarically over a wide temperature range, although the depth of formation differs from one kimberlite to another.

While there is considerable debate regarding the origin of the megacryst suite, field, petrographic and experimental evidence suggests a close genetic link between megacrysts and the host kimberlite. However, irrespective of the origin of the megacrysts, this suite reflects an isobaric magmatic event in the mantle over a time period of the order of 10 Ma immediately prior to kimberlite eruption. One possible interpretation of the range in megacryst zircon ages is that they reflect a period of kimberlite melt accumulation in the mantle, with eruption only occurring once a critical volume of melt has accumulated.

Episodes of kimberlite eruption in southern Africa also seems to follow continental epeirogenic episodes by about the same period (5-10 Ma) that is recorded by the zircon megacrysts. Further, these epeirogenic events appear to be roughly synchronous with reorganization of mid-oceanic spreading regimes around southern Africa. Post-Gondwana kimberlite and other alkaline activity in southern Africa thus seems more readily explained by tectonic melting triggers than plumes. In essence, the zircon dates suggest that the "anomaly" of disparate melting rates and eruption rates is not an anomaly at all, at least for kimberlites. But maybe also a great deal of other magmatic activity.–Andy Moore

Dear WM, I would like to bring your attention to this analysis of the thermodynamics of Hell. I wonder if this information is relevant to plumes.–Andy Moore

Dear WM, It has long been taught in geophysics and planetary physics courses, but not in mantle geochemistry courses, that the Earth started hot and was extensively differentiated during accretion. This knowledge goes back to the extremely influential papers of Francis Birch, including his classic 1952 paper, his 1965 Presidential Address and his energetics-of-core-formation papers. These papers form the foundations of modern geophysics but they are the antithesis of the Urey school of geochemistry (Urey, 1952) which produced many advocates of cold accretion, primordial Earth, crustal growth, continuous differentiation  and undegassed mantle. Thus, 1952 was a pivotal year for both mantle geophysics and mantle geochemistry. The two sciences diverged from that point on.

Schilling (Nature 242, 1973, page 565) states "Contrary to earlier views (Birch 1965), the model implies that plumes are transporting to the Earth's surface more primordial mantle material(s) than present in the low-velocity layer lying beneath those mid-ocean ridge segments remote from plumes." This was the nucleus of the geochemical version of the plume hypothesis. Tatsumoto (1978) and O'Hara (1973) almost immediately showed the flaws in Schilling's argument, and Tozer (1973 ) demonstrated the fluid dynamic implausibility of the geochemical model. Birch’s papers had already demonstrated that classical physics ruled out the assumptions in what became the canonical model of geochemistry.

The Birch ideas were extended to mantle geochemistry by Tatsumoto, Armstrong and Kay who developed top-down models of geochemistry. The mass balance associated with hot accretion and early differentiation was developed in many early papers and summarized in Chapter 8 of Theory of the Earth and Chapter 13 of New Theory of the Earth. The mass balance shows clearly that the whole mantle had to be processed to form the crust plus the kimberlites and carbonatites.–Don Anderson

Dear WM, The list of plume types, last updated in 2007, comprises fossil, dying, recycled, tabular, finger-like, baby, channelled, toroidal, head-free, cold, depleted residual, pulsating, throbbing, subduction-fluid fluxed, refractory, zoned, cavity, diapiric, starting, impact, incubating, incipient, splash, passive, petit, primary, real, secondary, satellite, strong, weak, tilted, parasite, thermo-chemical, asymmetric, fluid dynamic, depleted, stealth, lateral, CMB, shallow, 670-, mega-, super-, mini-, cacto, cold-head, headless, implausible (IMP), and plumelet.

It is ironic that Paul Tackley, in his review of P^3 in Science, criticized non-plume theories on the grounds that there are so many "special cases"!–Don Anderson

Dear WM, I would like to bring to your attention our new invited review paper Franke, D., Rifting, lithosphere breakup and volcanism: Comparison of magma-poor and volcanic rifted margins, Marine and Petroleum Geology (2012).

Key points are:

• Reevaluation of volcanism during rifting and continental breakup;
• Magma-poor and volcanic rifted end-member margin types are discussed;
• Study of the Laptev Sea, the South China Sea and the southern South Atlantic;
• Implications on the formation of rift-onset and breakup unconformities;
• A major controlling mode of hot-spot related mantle processes cannot be observed.

–Dieter Franke

Dear WM, In continuation of the theme of Anatomy of a Fallacy by E. Cañón-Tapia, further discussion of the logical fallacies underlying the canonical models of mantle geodynamics and geochemistry is given in the pages listed on the webpage General Theory of Plate Tectonics. This subject is also treated in the paper Anderson, Don L. (2002) Occam's Razor: Simplicity, Complexity, and Global Geodynamics. Proceedings of the American Philosophical Society, 146 (1). pp. 56-76. ISSN 0003-049X. –Don Anderson

Dear WM, Rampone, E., A.W. Hofmann, A global overview of isotopic heterogeneities in the oceanic mantle, Lithos, 148, 247-261, 2012. is a very important paper. First, it is the definitive explanation of how heterogeneous Earth's mantle is. Hofmann was among the first to propose a model to explain the extremely radiogenic 206Pb/204Pb isotopic composition of a rare group of OIB as consequence of deep recycling of slabs down to D'' depth. His 1988 paper, as well as his 1997 Nature paper and his 2003 Encyclopedia of Geochemistry paper are considered seminal by the geochemical plume-advocate community.

In the present paper, however, the word "plume" does not appear. The heterogeneities in Earth's mantle are attributed to poor homogenization of the upper mantle instead of to the arrival of deep, hot mantle plumes. That the MORB source is heterogeneous is definitively stated, in direct conflict with the old idea that MORB source is homogeneous.–Michele Lustrino

7 May, 2012,
Click here for a review by Don Anderson of the book "The Eruptions That Shook the World".–WM

4 May, 2012
Dear WM, Please add a link to my web page on the Ethiopian Rift Valley in my mantleplumes webpage. –Giacomo Corti

30 April, 2012
Dear WM, I would like to draw your attention to this article "A hotspot alternative" recently posted on about.com.–Phil Gibbard

31 March, 2012
Dear WM, I think it would be a good idea to post the classical paper by Roeder & Emslie (1970) which, for the first time, defined the correlation of Mg/Fe between olivines crystallizing from basaltic melts. It is a very old paper, but all Tp estimates are based on this paper. Considering that the alleged higher Tp of mantle-plume-derived melts are based on the presence of high-Mg olivines, interpreted as an evidence for high-Mg liquids, and, consequently, higher than "usual" temperatures (to extract more Mg from peridotites) it would be instructive to have such a paper posted on the site.–Michele Lustrino

29 March, 2012,
Dear WM, We have two hard constraints on the temperature of the mantle, the P and T of melt extraction at Hawaii and at ridges. These constraints require that the geotherm at ridges must graze the volatile-free lherzolite solidus at about 60 km depth. The standard complaint against this hard constraint is that we are missing this or that component. But at these low pressures, we now have data in 6-space (CaO-MgO-Al2O3-SiO2-Na20-FeO) and 98% of the composition of basalts so it is unlikely that any unmodeled component or other will change the conclusion much. At Hawaii, there is one published trend of olivine-controlled crystallization (Clague), which requires melt extraction at much higher pressures. The olivine-rich end of thIs trend intersects the experimentally-determined trend of pressure vs initial melt composition at about 5 GPa. So for this trend, the melts come from about 150 km depth, and the geotherm at Hawaii must graze the geotherm at about this depth. In my recent J. Pet. paper, for higher pressures, I assumed a 1500 C adiabat at Hawaii. For ridges, I connected the 60 km point on the geotherm at about 1.3 GPa with what I assumed was a fairly uniform temperature (a 1500 C adiabat) at great depths. Except for the temperature constraint at ~1.3 GPa. My guess that temperatures at great depth are fairly uniform could easily be wrong. But I feel very secure about the two different P-T ranges for melt-extraction at Hawaii and MORBs.–Dean Presnall

28 February, 2012
Dear WM, There have been several papers on seismology around Hawaii published recently. There are various predictions for what the observations should show, if there is a plume. These include low absolute velocities, depressed 410, elevated 650, a parabolic trend of azimuthal anisotropy and shear wave splitting, ponding under 650 km, and a dragged and sheared slow plume head extending to the NW. Thus, from seismology, the plume idea is eminently testable. Recent papers show that none of these predictions are true and different, detailed rationalizations have been offered for each failure. Thus, the plume hypothesis cannot be falsified.

The polarization anisotropy of the Pacific, is not due to LPO or oriented olivine. It is due to oriented melt-rich lenses. The prediction is that azimuthal anisotropy should be much less than the radial, as observed. If the plate direction is EW the fast direction is to the W, dipping down slightly to the W, and SH is faster than SV by more than the splitting delay, as observed.

Attributing the observed anisotropy to fossil anisotropy is a cop out. The predicted asthenosphere flow in the plume model is to the NW but all indications are that the trend of the volcanic chain is not in the direction of plate motion over the mantle.

When properly interpreted, anisotropy is a powerful constraint. For example, the LLAMA model suggests that the melt content is 1- 2%, something that cannot be inferred with confidence from the seismic velocities themselves. It also shows that orientation of olivine cannot be the explanation for seismic anisotropy.–Don Anderson

2nd October, 2011
Dear WM, The data published in nearly all the petrology/ geochemistry papers on basaltic rocks can be explained without invoking any thermal anomaly. The presence of mantle plumes is not necessary and, in many cases, it is in disagreement with the investigated phenomenology. An example is the recent paper published in G³ by Beier et al. on Louisville seamounts. The authors state, "Unlike Hawaiian volcanoes, Louisville volcanoes appear not to pass through a sequence of evolutionary stages characterized by older tholeiitic basalts overlain by incompatible element enriched alkalic and silica-undersaturated lavas". Moreover, they state "The youngest lavas from a given Louisville seamount tend to have the least enriched incompatible element compositions." They interpret these features (in contrast with the plume theory) in the following way: "This unusual chemical evolution may be the result of re-melting of heterogeneous hot spot mantle that was partially depleted during the earlier, age progressive stages." These are ad hoc solutions. Interestingly, the authors say "Large fracture zones apparently had no significant effects on the composition of Louisville magmatism." even though the Louisville seamount chain is parallel to the large Heezen and Tharp fracture zones. The authors continue: "magmatism at several Louisville volcanoes took place over a protracted period of time, with temporal chemical variations among the lavas erupted on a particular seamount.". The igneous activity on each seamount seems to last from 10 to 23 Ma, much longer than other typical Pacific seamounts.

6th October, 2011
Dear WM, The papers Zhao et al., Origin of the Changbai intraplate volcanism in Northeast
China: Evidence from seismic
tomography, Chinese Science Bulletin, 49 ,1401-1408, 2004, and Wortel & Spakman, Subduction and Slab Detachment in the Mediterranean-Carpathian Region, Science, 290, 1910-1917, 2000, along with various of Marjorie Wilson's, justify the statement "all the volcanoes in Europe, North Africa and China that have previously been attributed to plumes are now recognized as natural results of plate tectonics." These areas are similar to Yellowstone-CRB in that enormous volumes of oceanic crust and plate have been shoved under these regions.–Don Anderson

26th June, 2011
Dear WM, The recent paper by Christoffersson & Husebye (2011) shows that ACH tomography does not work. This is confirmed by the recent work at Hawaii by Cao et al. (2011), who show that the structures formerly claimed to exist beneath Hawaii on the basis of ACH do not exist after all.–Don Anderson

3rd June, 2011
Dear WM, The recent paper in Science by Cao et al. (2011) destroys the previous Science papers that "proved" the existence of a plumes under Hawaii, by authors such as Wolfe and Montelli. It confirms results published in an old and excellent paper by Katzman et al. (1998), which uses a more data and advanced theory and comes to an opposite interpretation of the final results. Katzman et al. (1998) use a lot more than just SS and also allow for anisotropy.

The "hot-megablob" 2000 km W of Hawaii is one of many in the Pacific that have nothing to do with "plumes" or particularly hot mantle. There are lots of places in the world, Pasadena is one, with thinner (hotter) transition regions.

I encourage you to read the attached and compare it with the recent Science paper.–Don Anderson

16th March, 2011
Dear WM, I followed your suggestion and acquired a free instructor's evaluation copy of your book "Plates vs Plumes" from Wiley-Blackwell. I'll be teaching a 1-unit nonorthodox-geodynamics course in the fall, and will seriously consider your book.

21st Feb., 2011
Dear WM, I would like to bring to the attention of website visitors a new journal recently established, the Journal of Universal Rejection (JofUR). For those wishing to submit papers criticising the plume hypothesis, this might provide a quick route through the publication process up.–Peter Vogt

Discussion of the webpage "The highly magnesian dike rocks of Vestfjella (W Dronning Maud Land, Antarctica): implications for sublithospheric mantle sources & the origin of the Karoo LIP." has been moved to a separate Discussion page.–WM

21st Sept., 2010
Dear WM, A recent paper argues that the Siberian Traps and the NAIP were active for 250 Ma and "this rules out an upper mantle explanation and requires a deep mantle plume explanation". Thus, a short duration (1 Ma), a moderate duration (3 Ma) and a long duration (250 Ma) are all used as arguments for a plume origin. Smirnov & Tarduno just use the long duration as a plume diagnostic. This confirms, again, that the plume hypothesis cannot be tested or falsified as it stands. The updated list of plume variants now includes fossil, dying, recycled, tabular, finger-like, baby, channeled, toroidal, head-free, cold, depleted residual, pulsating, throbbing, subduction-fluid fluxed, refractory, zoned, cavity, diapiric, starting, impact, incubating, incipient, splash, passive, primary, secondary, satellite, strong, weak, tilted, parasite, thermo-chemical, asymmetric, fluid dynamic, depleted, stealth, lateral, CMB, shallow, 670-, mega-, super-, mini-, cacto-, cold-head, headless, petit, implausible (IMP), zombie, plumelet, pizza, spaghetti and flattened-onion plumes. Many plume models now involve 2000-5000 km of lateral flow, an attribute of many non plume models. The number of plume types is now essentially identical to the number of generally accepted plumes in plume catalogues and 8 times more than what are considered to be “primary” plumes.–Don Anderson

19th Sept. 2010
Dear WM, Visitors to the website might be interested in this quote, from Davis (1926): "It has been remarked that the majority of astronomers explain the craters of the moon by volcanic eruption–that is, by an essentially geological process–while a considerable number of geologists are inclined to explain them by the impact of bodies falling upon the moon–that is, by an essentially astronomical process. This suggests that each group of scientists find the craters so difficult to explain by processes with which they are professionally familiar that they have to recourse to a process belonging in another field than their own, with which they are probably imperfectly acquainted, and with which they therefore feel freer to take liberties.”–Bruce Julian
Davis, W.M., Biographical memoir of Grove Karl Gilbert, 1843-1918, Mem. Nat. Acad. Sci., 21, 5th Mem., 303 pp., 1926.

11th Sept. 2010
Dear WM, I would like to bring your attention to an interesting article posted on the website of the Santa Fe Institute "Modeling shows scientific peer review system sensitive to bad refereeing"– Romain Meyer

23rd April, 2010
Dear WM, There have been numerous ad hoc attempts to explain why bathymetry violates the square-root-age relation after 70 Ma but none of them are consistent with the continued growth of the seismic lid across the whole Pacific. The latest attempt to unflatten the seafloor is in the issue of Science that hit the stands on April Fools Day 2010 but has a publication date one day later. I discuss the flattening problem in the attached document.–Don Anderson

22nd April, 2010
The process by which science advances is a conservative one. That is, each step of the way involves documentation that the new information is reproducible and consistent with the existing body of knowledge. For most day-to-day operations of science, this approach is reasonable and successful; inaccurate observations and incorrect deductions are weeded out, and accurate observations and deductions are added to the fabric of knowledge. However, when new observations or arguments do not fit into the existing paradigm, there is a strong tendency for them to be rejected by the scientific community. The larger the shift of paradigm required to accommodate the new information, the more harsh and emotional is likely to be the rejection.–Harry W. Green, from "Psychology of a Changing Paradigm"

12th March, 2010
Dear WM, I am comparing different scientimetric systems; ISI Thomson (their impact factor system) and two new systems (SNIP and SJR) provided by SCOPUS, for Earth Science journals. To test these systems I need a selected pool of journals, which are considered to be the top journals among researchers.

In order to do this I created an on-line voting system with a list of 200 Earth Science journals. Science, Nature and Nature Geosciences are not included for obvious reasons and some other journals are absent because they are not covered by all three systems. I would be most grateful if website visitors would visit this site and vote.–Alexei Ivanov

24th Feb., 2010
Dear WM, I send this published paper for listing on the website. We met briefly when you gave a talk at Univ. Wisconsin a few years ago. I was "plume neutral" before I started the project, working on a major shear zone in the western US (western Idaho shear zone). An inadvertent outcome of our work was the suggestion that the Yellowstone (and Newberry) hotspots seem to initiate on the Mesozoic shear zone (perhaps on the termination of the shear zone) and the Columbia River basalt feeders seem to follow the shear zone exactly. So, I found myself increasingly thinking that the initiation of the hotspot was a result of plate tectonic processes (I can't say anything about the Yellowstone hotspot at present - only the initiation). Anyway, here is a contribution from the structural geology angle if it is of interest.–Basil Tikoff

19th Dec., 2009
Dear WM, I found an old paper entitled “The Method of multiple working hypotheses” by T.C. Chamberlin published in Journal of Geology, 5 (1897) 837–848. It has close bearing on current debates on the mantle plume hypothesis. The mantle plume hypothesis has often been linked to the origin of oceanic island basalts (OIB) and continental flood basalts (CFB), with potential implications for the composition of the lower mantle and even the core-mantle boundary layer. The debates centered on this issue closely mirror imperfections of our knowledge of mantle geochemistry. The issue of the origins and evolutionary mechanisms of oceanic and continental basaltic magmas is a vast subject. For anyone who wants to argue for/against the mantle plume hypothesis, it is necessary to clarify the positions of those said to hold divergent views.

The supposed divergence here includes not only acceptance/rejection of the evidence for the existence of mantle plumes (and the implications for the geochemical nature of their postulated ultradeep mantle sources), but also confidence/doubt in the applicability of the plume hypothesis to the origin of continental mafic rocks. The view that this position is somehow subjective may arise from confusion between objective reality (the existence of geochemical varieties of OIB and CFB ) and a human construct (a cherished but subjective model for the origin of observed features). The problem appears to be one of “academic affection” in the method of multiple working hypotheses (Chamberlin, 1897). On one hand, when a model has assumed the status of reality in the minds of its adherents, the whole system under discussion is viewed in the context of the model and thus there is great resistance to any attempt to challenge it.

28th Sept., 2009
Dear WM, I will reverse my color scale–to make Bruce happy–Rob van der Hilst

28th Sept., 2009
Dear WM, Concerning the recent Science article "Scoping Out Unseen Forces Shaping North America", Science magazine doesn't seem to proof-read its figure captions. The caption to the "What a drip!" figure says that blue colors represent slower waves and reds represent faster, the opposite of the essentially universal convention. The blue anomaly in their picture, however, has HIGH wave speeds, as the text makes clear.–Bruce Julian

14th Sept., 2009
Dear WM, Rejectica Mathematica–I love it. I suggest for us, Acta Geophysica Trashica–Chris Scholz

28th Aug., 2009
Dear WM, I recently discovered your website. What a great resource for the public!

I am a professional geneticist and an amateur naturalist with an interest in geology. I give geology walks in a local park in Seattle, Washington, USA as a volunteer. Even as a (non-geologist) scientist, I have trouble finding, accessing, and understanding professional geology papers in order keep up with current thinking on the formation of the American Pacific Northwest. Your website is a pleasure to read. Free access and a focus on models and controversies allows an amateur like me to get much better understanding of the field than I have generally been able to get through always-out-of-date popular geology books and my limited access to and awareness of published papers.

The various articles are also generally clear and clearly illustrated. Obviously the more knowledge of geology one has, the more one can understand and glean from the articles, but as a self-educated amateur, I am pleased to find them relatively easy to read.

Thanks so much for providing this resource!–Paul Talbert

20th Feb., 2009
Dear WM, An interesting piece of work was recently published: Polyakov V.B. Equilibrium iron isotope fractionation at core-mantle boundary conditions. Science, 323, 912-914, 2009 on the theory of stable isotope fractionation with implications for iron isotopes in the Earth and other planets. It appears that enrichment of the Earth and Moon by heavy iron isotopes compared to Mars, Vesta and chondritic meteorites can be explained by equilibrium fractionation of iron isotopes at pressures of the Earth’s core-mantle boundary.

This new model has two important implications for Earth sciences. First, it suggests that the separation of iron, which formed the Earth’s core, happened at high pressure and not in a shallow magma ocean. Second, it suggests that plumes, if they originate at the core-mantle boundary and feed ocean-island volcanism e.g., at Hawaii, could be distinguished from shallow-sourced magmatism by iron isotope measurements in OIB and MORB basalts.

The core contribution at Hawaii postulated from earlier Re-Os isotope work was ruled out by a later tungsten isotope work (Scherstén A., Elliott T., Hawkesworth  C., Norman M. Tungsten isotope evidence that mantle plumes contain no contribution from Earth’s core. Nature, 427, 234-237, 2004so this could provide a new investigative approach–Alexei Ivanov

11th Feb., 2009
Dear WM, I would like to draw the attention of website visitors to the NY Times article "Darwinism Must Die So That Evolution May Live". Are there are some parallels to be drawn in plume science?–Andrew Alden

5th Feb., 2009 Dear WM, I would like to update website visitors on the progress of our initiative to donate copies of the P4 book. I just received this photo showing the presentation by the Alumni Association, of copies to Obaferni Awolowo University, Nigeria.–Donna Jurdy

29th Dec., 2008
Dear WM, In many recent plume-advocacy papers plumes are not the essence of the story and none of the data requires them, yet “the plume” is in the title and the conclusion. Putting a plume in for the hell of it is “gratuitous plumeology”. Such a plume is a ”zombie plume” since there is no evidence for it, and it therefore cannot be refuted or killed! Examples include Konter et al. 2008; Cadoux et al. 2007; Sen et al. 2008.

All indications in these papers point to asthenospheric and metasomatic shallow sources and against any deep, hot source. Some involve no connection between flood basalts (plume heads) and volcanic islands (plume tails), yet plumes and plume heads are prominent in titles and abstracts, and are sometimes only there. The data would be equally well satisfied by melting of cold mafic chunks and the conclusions would make equal sense if “plume” were replaced by “delaminated crust”, “Reunion-like isotopic source”, “metasomatised mantle” or “heterogeneity”, and so on.

Temperature, heatflow, depth and origin in a thermal boundary layer are the defining characteristics of a mantle plume, but are usually not mentioned or constrained in any way in plume-advocacy papers. The data are almost always consistent with ambient temperature, and non-plume tectonic events, such as delamination, rift or edge-driven convection, or metasomatism, and often even interpreted in those terms. However, they are usually implied to have occurred co-incidentally with, been caused by, or been an intricate part of an assumed plume. Such an approach at best lacks innovation and at worst is unscientific and hampers progress.–Don Anderson

17th Nov., 2008
Dear WM, I would like to bring to your attention a new branch of science–"zombie science". It is discussed in the paper "Charlton, B., Zombie science: A sinister consequence of evaluating scientific theories purely on the basis of enlightened self-interest, Medical Hypotheses, 71, 327-329, 2008." In a nutshell, "zombie science" is science that is dead but will not lie down. –Don Anderson

27th Oct., 2008
Dear WM, I would like to highlight a comment posted on my blog on the paper Konter, et al., One hundred million years of mantle geochemical history suggest the retiring of mantle plumes is premature, Earth Planet. Sci. Lett., in press, 2008. I think the comment might be of interest to visitors to your website.–Rex Pilger

5th Sept., 2008
Dear WM, An article by Drs. Ingrid Ukstins Peate and Scott Bryan in the current issue of Nature Geoscience would be interesting for geologists involved in the mantle plume debate. It is entitled “Re-evaluating plume-induced uplift in the Emeishan large igneous province”.–Todd Rainey

24th August, 2008
Dear WM, As part of my "Integrating Research and Education" project (funded by NSF), we did a number of "guided discovery exercises" for students to explore interesting and important topics. Kent Ratajeski did a nice unit on "Is Yellowstone Volcanism Caused by a Deep-Seated Mantle Plume?". Please feel free to link to our metadata page about this site if appropriate on your Mantle Plumes site.–Dave Mogk

22nd August, 2008
Dear WM, I propose that the well-known acronym “OIB”, for “ocean island basalts”, is henceforth used to denote “oceanic intraplate basalts”.

There are two reasons for my proposal:

(i) Islands are merely the tops of submarine volcanoes and the term “ocean island basalt” does not include the thousands of seamounts that lie scattered throughout the Pacific and other ocean basins. Most of these seamounts do not define systematic chains, a fact that is of relevance to the plume hypothesis (the “galaxy effect”).

(ii) The term “ocean island basalt” by itself does not say anything about the intraplate origin of the islands in question. There are oceanic island arcs related to subduction which are a plate boundary phenomenon. “Ocean island basalt” should include the basalts of the oceanic island arcs, inasmuch as they are “oceanic”, “islands”, and erupt “basalt”. Thus, OIB and IAB are not really exclusive.

Of course, there are rocks other than basalt in arcs, and I am happy if even the “B” is replaced by something general – simply R for “rocks?”.

But if the term "OIB" is to be continued, then, to avoid these problems, and to ensure terminological accuracy, OIB should be used for “Oceanic Intraplate Basalts”. If used in this way, the term means that the said basalts are “oceanic”, and formed by “intraplate” mechanisms, and therefore island arc basalts (IABs) would be automatically excluded.

Comments are welcome.–Hetu Sheth

6th August, 2008
Dear WM, I find the article: Gutierrez-Alonso, Gabriel; et al. 2008 Self-subduction of the Pangaean global plate, Nature Geoscience, 1, 549-553 an intriguing and thoughtful attempt to explain the initiation and pattern of the break-up of Pangaea on the basis of a "platonic" interpretation of plate tectonics geology. I recommend that it be listed under “A glance at today’s paper” on the MantlePlumes site.–Todd Rainey

2nd July, 2008
Dear WM, I find it interesting that two new papers listed in the Recent Scholarly Articles section of this website both invoke secondary, non-plume mechanisms together with primary, plume-related ones to explain the origin of volcanism around Samoa (Koppers et al., 2008) and the Columbia River (Camp & Hanan, 2008). Apparently, plume advocates are increasingly influenced by non-plume mechanisms for generating melting anomalies such that hybrid models are increasingly appearing in the literature.–Don Barrie

30th June, 2008
Dear WM, For those interested in Pacific geology, the Smithsonian Institution has recently scanned and placed on line ALL of the U.S. Exploring Expedition reports. These were originally issued only in a printing of 100, and are rare birds indeed. J.D. Dana's report on Geology is v. 10 of 23 volumes. There are 4 separate indices for the one volume, plus an Atlas of plates. Ch. 7 has Dana's review of Volcanic Action in the Pacific, in which he propounds his fissure-control theory of linear chain volcanism. Ch. 3 on Hawaii also develops some of these ideas.

The URL is:
www.sil.si.edu/digitalcollections/usexex/

–Jim Natland

9th May, 2008
Dear WM, I bring to your attention our recent paper Clouard, V. and M. Gerbault, Break-up spots: could the Pacific open as a consequence of plate kinematics?, EPSL, 265, 195-208, 2008. Two comments were also published, one in Nature Geoscience, and the other one in New Scientist. I would like to thank you very much for your management of the useful "mantleplumes" website.–Valerie Clouard

7th March, 2008
Dear WM, Andrew Alden, the host of the science blog About.com (Geology) has posted another interesting discussion of hotspot models "A Hotspot Alternative". This news website is a popular source of geological information from a very respected educator.–Greg McHone

29th Feb, 2008
Dear WM, A Russian saying is that bad is the scholar who doesn ’t want to become a great scientist. In his recent correspondence to PLoS Computation Biology ‘On the process of becoming a great scientist’ Morgan Giddings provides an excellent recipe for how to achieve this. We need to be open to challenging ideas, courageous enough to speak out irrespective of our age or status, and wise enough to encourage others to do the same, even if it flies in the face of our own theories.–Alexei Ivanov

28th Jan, 2008
Dear WM, Check out the movies of plume convection at Westfälische Wilhelms Universität Münster (click on the pictures).–Jack Holden

10th Jan, 2008
Dear WM, This is one of the most informative websites I've visited. It has been a tremendous help in keeping up with the latest literature.
Keep up the good work.–Vince Neall

7th Jan, 2008
Dear WM, PDFs of most of my publications since 1958 are now available on line.–Don Anderson

5th Jan, 2008
A paper entitled "Siberian flood basalt magmatism and Mongolia-Okhotsk slab dehydration", authored by Konstantin Litasov and myself, is posted for public view in Nature Precedings service. Any comments are welcome.–Alexei Ivanov

3rd Jan, 2008
Dear WM, The current issue of Scientific American has an article on "moving" hot spots that may be of interest to website visitors–"Hotspots Unplugged". Refreshingly, this article takes a less dogmatic approach to hot spots than most articles aimed at lay readers. Thanks for your informative MantlePlumes website! –Steve Russell, Seattle

8th Dec, 2007
Dear WM, Visual inspection of tomographic cross sections has led to widespread acceptance of whole mantle convection, deep slab penetration and deep mantle plumes. What are the odds that one could find such cross sections, even if the mantle had completely random structure? Considering the resolution of long period tomography, one expects , for a completely random mantle, about 4 mantle crossing alignments of either red or blue colors. This is not too different from the expectations of obtaining a flush or three cherries in various well known games of chance.

24th Nov, 2007
Dear WM, Bourdon et al. (2007) state “Anderson and Natland favour the idea that all plumes originate from the core–mantle boundary.” My befuddlement at this conclusion is summarized by something Johnny Carson used to say with his classic straight face on the Tonight show, usually in response to some non sequitar from Doc Severinson: “I did not know that.”– Bob Stern

29th Oct, 2007
Dear WM, The “lower mantle” proper starts at about 1000 km (Bullen's Region D). There has been enormous semantic and logical confusion, with some investigators assuming that if slabs sink below 650 km they enter the “lower mantle” and “therefore” sink to the core mantle boundary. Slabs can sink below 650 km and still stop at 800-1000 km as shown by numerous papers. This appears to be an important geodynamic boundary. Slab pull gets very weak below 300-400 km.

The “upper mantle” and the Transition Region (Bullen’s Region C) contain two major seismic discontinuities, several low velocity zones, and much seismic scattering.

Slabs sinking below whatever depth must be replaced but not necessarily by narrow upwellings. The mantle below 410 km, or 500 km, or between 650 and 1000 km is displaced upwards as slabs sink into it. Even without slabs, radioactivity gives broad diffuse upwellings and narrow downwellings. A mantle heated only from below will give narrow upwellings (if pressure and radioactivity are ignored, as in much plume modeling) and diffuse downwellings, as Morgan pointed out in his plume papers. There is no mass balance or chemical reason for having slabs return or be part of a closed cycle. Delaminated lower crust can, however, recycle on a short timescale.

4th Oct, 2007
Dear WM, Please post this additional Powerpoint presentation "The Circum-Mediterranean Anorogenic Cenozoic Igneous Province" by myself and Marge Wison.–Michele Lustrino

2nd Oct, 2007
Dear WM, The list of plume types assembled by Michele Lustrino and Eugenio Carminati considerably enriches the plume vocabulary. The updated list now includes fossil, dying, recycled, tabular, finger-like, baby, channelled, toroidal, head-free, cold, depleted residual, pulsating, throbbing, subduction-fluid fluxed, refractory, zoned, cavity, diapiric, starting, impact, incubating, incipient, splash, passive, primary, secondary, satellite, strong, weak, tilted, parasite, thermo-chemical, asymmetric, fluid dynamic, depleted, stealth, lateral, CMB, shallow, 670-, mega-, super-, mini-, cacto, cold-head, headless, petit, implausible (IMP), and plumelet!

The number of plume types is now essentially identical to the number of generally accepted plumes in plume catalogues and 8 times more than the primary, or real plumes (oops! That’s another one).–Don Anderson

10th Sept, 2007
Dear WM, I'm quite intrigued by all the fascinating ideas that are developing. It's an exciting time and I'm disappointed that the new edition of the introductory geology text I use still relies heavily on plume theory to explain almost everything from LIPs, to aulacogens, to aseismic ridges, to the breakup of Pangea.

The tide seems to be turning even for textbook writers, however, as evidenced by the following statement, found in the chapter on plate tectonics: "Of the forty-five hot spots identified on Earth, only twelve show evidence of a deep, continuous plume in the underlying mantle." (Carlson et. al. 2008, Earth Revealed, Physical Geology, 7th ed., McGraw Hill).

Still a dubious statement, of course, but progress, perhaps.–Don Barrie

7th Sept, 2007
An Implausible Mantle Plume (IMP). I like It! A new category of plumes or non-plumes, to join cavity, diapiric, starting, impact, incubating, incipient, splash, passive, primary, secondary, satellite, parasite, thermo-chemical, fluid dynamic, depleted, stealth, lateral, super-, mini-, cacto, cold-head, headless, petit and baby plumes, and the plumelet, hot head, cold head and headless subspecies. Each, including IMPs, is the result of an after-the-fact observation or failure of a prediction. An IMP, of course, is of the family of devil's advocates and Maxwell Demons, both relevant to plumes. I am certainly an advocate of imps, the little devils!– Don Anderson

3rd Sept, 2007
Has anyone compiled a data set for lithophile isotope compositions of mineral separates (ol, cpx, opx) from mantle rocks similar to the work by Mattey et al., (1994: Oxygen isotope composition of mantle peridotite) that can be used as a proxy for mantle compositions to compare with conventional basalt compositions (e.g., Zindler & Hart, 1986)?–Sami Mikhail

20th July, 2007
The cover for the forthcoming P^4 book (to be printed in August) may be viewed by clicking here. Please send your comments to the website manager.
Comments to date:
1. "It's wild". - Jack Holden
2. "awesome". - Ian Norton
3. "AWESOME". - Scott King
4 "It's very good! Much better than a photo of a volcano or another section through the Earth." - Godfrey Fitton
5. "Looks great!!! " - Erin Beutel
6. It seems to me to be looking at the earth and at the special volume and saying "what the hell have I done???" - Scott King
7. The cover page appears to convey that it is a "mental
plume". The cover page is the most appropriate one to represent the mantle plume debate. - Senthil Kumar
8. I find the cover GREAT.– Michele Lustrino
9. You must be joking about the cover. It is embarrassing.– Anonymous
10. Very impish. Whose cartoon is it?–Jim Natland
WM: The cartoon is Fig. 2 from Ch. 45 of the book.
11. The proposed cover cartoon
is fine for a chapter intended to be humorous and witty. It's too informal
for the cover of such a serious volume.– Anonymous
12. There's simply nothing - no matter how wonderful - that EVERYONE will like. It does not exist.–Donna Jurdy

27th April, 2006
Dear WM, Richard Ernst has asked me to take responsibility for posting notices of upcoming conferences on the www.largeigneousprovinces.org website. I would like to ask all mantleplumes.org readers who are planning conferences on the following topics to contact me with a synopsis and I will post it on www.largeigneousprovinces.org and give them free publicity.

• LIPs
• The generation of silicic magma at LIPs
• Plumes and LIPs (again)
• SLIPs
• The generation of mafic magma at SLIPs
• The role or absence of  plumes for SLIP genesis
• Back arc magmatism
• Volcanic Rifted Margins
• SLIPs and crustal building

– Sami Mikhail

5th April, 2006
LIPs Commission meeting during IAVCEI conference in Guangzhou, China, May 14-18 2006, Monday May 15, 6-7 pm All LIPs researchers welcome. Please send suggestions for additional agenda items to Richard Ernst Note: The announcement made in GSA Today March 2006 that Richard is dead was greatly exaggerated. – WM

Agenda items:

1. Defining LIPs-- discussion of recent progress toward an "official"
   definition.
2. Role of the LIPs Commission-- planned and future activities
3. Expanding content on our website.

13th March, 2006
A new Powerpoint presentation has just been posted: Self-organized breakup of Gondwana: An argument against the deep mantle plume paradigm by James Sears. This is from a lecture he gave at Durham today, where he presents a novel model to explain the location of LIPs. – WM