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   Definition of a plume
What is a plume?
  • plume that has not yet reached the surface (embryonic plume?–Isse et al., 2016)
  • fossil plume (Stein and Hofmann, 1992; Rotolo et al., 2006)
  • dying plume (Davaille and Vatteville, 2005)
  • recycled plume head (Gasperini et al., 2000)
  • tabular plume (Hoernle et al., 1995)
  • finger-like plume (e.g., Granet et al., 1995; Cadoux et al., 2007)
  • baby plume (Ritter, 2006)
  • channelled plume (Camp and Roobol, 1992; Oyarzun et al, 1997)
  • thoroidal plume (Mahoney et al., 1992)
  • head-free plume (e.g., Ritter, 2006)
  • cold plume (Garfunkel, 1989; Hanguita and Hernan, 2000)
  • depleted residual plume (e.g., Danyushevsky et al., 1995)
  • pulsating plume (Krienitz et al., 2007)
  • subduction fluid-fluxed refractory plume (Falloon et al., 2007)

ad hoc plume concepts, from a Powerpiont presentation, by Michele Lustrino & Eugenio Carminati

Definition of a plume
by
D.L. Anderson

European "plumes" are the leaking of fluid released from the top of the transition zone.

Marge Wilson, lecture to Dept. Earth Sciences, Durham University, 1st May, 2007

“The stealth plume”

... Another“ invisible” core heat loss mechanism was proposed by Malamud and Turcotte (How many plumes are there?, Earth Planet. Sci. Lett., 174, 113–124, 1999) who, by adding in contributions from 5200 unseen “stealth” plumes that were assumed to follow a power-law size distribution, estimated a plume heat flux as high as 35% of surface heat flux; these unseen plumes would transfer core heat into the general mantle.

Mittelstaedt & Tackley, 2006

In fluid mechanics literature, "plumes" refer to upwelling or downwelling driven by self-buoyancy.

Korenaga, J., Earth Planet. Sci. Lett., 234, 385-399, 2005 (p 391)

“We must be sure that we are all talking about the same thing.”

Macelwane, J.B., Forecasting earthquakes, Bull. Seismol. Soc. Am., 36, 1-4. 1946.

"... and plume in mind of one researcher is not the same as the plume in mind of others ..."

Alexei Ivanov, October 2004

Morgan (1971) originally proposed that “plumes”, which he described as hot upwellings of relatively primordial material, rise from the deep mantle and feed surface “hot spots”. Such plumes rise because of thermal buoyancy, and must originate at a thermal boundary layer. The only such layer known to exist in the deep mantle is the core-mantle boundary (D"), and thus “Morgan-type” plumes are generally assumed to rise from this layer.

Irrefutable evidence for such plumes has not been confirmed, and contrary, or unexpected observations are often reported. On the other hand, low-wave-speed seismic anomalies with different shapes, e.g., shallow, or very wide bodies have been found. Such observations have led to diversification of the range of features that scientists call “plumes”.

A clear, widely accepted definition of a plume does not currently exist. As a result, scientific interaction is often hampered because individuals use the word “plume” to mean different physical models without each other realising. Furthermore, it is essentially impossible to disprove the plume hypothesis at any given location because the term “plume” has become so vague. This webpage will air this subject, and post comments, suggested definitions and contributions.

So how do you think a “plume” should be defined?

Angelo Peccerillo, January 2005 – the "Teleplume"

It has been suggested (EOS, 85, no. 50, p. 541) that there is a plume below Italy, resting (after its long and tiring journey from the core-mantle boundary) since at least 60-70 Ma at a depth of 500-600 km. In spite of being so far from the surface, it was able to open the Balearic and Tyrrhenian basins (> 800 km of extension) and push the lithosphere eastward, generating the Apennine chain. A plume which is able to cause such a disaster from such a large distance could be named a "Teleplume".

Godfrey Fitton, October 2004

"A plume is an upwelling of hotter stuff from depth that carries a distinctive chemical and isotopic signature."

Andy Saunders, March 2004, “Plumes and Plumage” Symposium of the Herdman Society, Dept. Earth Sciences, Liverpool University

“A mantle plume is a localised1, roughly axisymmetric2 upwelling of buoyant3 rock4, originating from a boundary layer deep5 within the Earth6

This should be considered in conjunction with the “small print” which is:

  1. Localised on a global scale – typically having a conduit diameter of ~102 km, but a head diameter of up to 2 x 103 km.
  2. The head may distort as it impacts the base of the lithosphere.
  3. They are thermally and/or compositionally buoyant, but probably hotter then the surrounding mantle.
  4. Rock, plus melt at higher levels.
  5. Unspecified – 670 km or core-mantle boundary are likely candidates.
  6. Plumes may occur on other planets, such as Venus.

... some random downloadings from Google contributed by Don Anderson ....

Geol: A column of magma rising from the lower mantle and spreading sideways on reaching the base of the lithosphere, proposed as an explanation of the motion of lithospheric plates and of sites of volcanic activity away from plate margins.

1971 W. J. MORGAN in Nature 5 Mar. 42/2, “I now propose that these hotspots are manifestations of convection in the lower mantle which provides the motive force for continental drift. In my model there are about twenty deep mantle plumes bringing heat and relatively primordial material up to the asthenosphere and horizontal currents in the asthenosphere flow radially away from each of these plumes.

John Hernlund

“An upwelling hot solid body arising from a thermal boundary layer deep in the mantle, a natural and essential feature of bottom-heated convection.”

Mark Jancin, March 2004

“Plume: a term that amounts to a semantic garbage disposal that does nothing to clarify the thoughts of either the author or the reader.”

p. G-12 (in glossary) of Chernicoff, C. and R. Venkatakrishnan, 1995, Geology (An Introduction to Physical Geology):  Worth Publishers, Inc., NY, NY, 593 p + Appendices:
 
“ plume:  an upward flow of hot material from the Earth's mantle into the crust.”
 
p. 555 (glossary), W.K. Hamblin, 1989, The Earth's Dynamic Systems (A Textbook in Physical Geology), 5th ed.:  Macmillan Publishing Co., NY, NY, 576 p:
 
“ mantle plume:  a buoyant mass of hot mantle material that rises to the base of the lithosphere.  Mantle plumes commonly produce volcanic activity and structural deformation in the central part of lithospheric plates.”
p. 391, Bates R.L. and J.A. Jackson (eds), 1984, Dictionary of Geological Terms, 3rd ed.:  under direction of the American Geological Institute; Doubleday, NY, NY, 571 p:
 
“plume:  a persistent pipelike body of hot material moving upward from the Earth's mantle into the crust.  Its surface expression may be a hot spot.”
p. 513, Bates R.L. and J.A. Jackson (eds), 1987, Glossary of Geology, 3rd ed.:  published by the American Geological Institute, Alexandria, VA, 788 p:
 
“ plume:  (a) a localized body of volcanic rock rising into the crust from the mantle and thought to be the causal mechanism of a hot spot.”
 
“ hot spot (p. 314):  a volcanic center, 100 to 200 km across and persistent for at least a few tens of millions of years, that is thought to be the surface expression of a persistent rising plume of hot mantle material.  Hot spots are not linked with arcs, and may or may not be associated with oceanic ridges.”

Griffiths and Campbell (1990):
Basalts erupted at oceanic and continental hotspots originate from zones of melting having potential temperatures greater than normal melting and therefore are attributed to plumes of hot material upwelling from deep in the mantle…

Davies (1999):
Mantle plumes are buoyant mantle upwellings that are inferred to exist under some volcanic centres.
Turcotte and Schubert (2002):
Mantle plumes are quasi-cylindrical concentrated upwellings of hot mantle rock and they represent a basic form of mantle convection (p.15)

Dickinson, W.R., 2003:
Viewing “plume” as just shorthand for any of various kinds of anomalously hot mantle seems to me to be a liberating point of view.

Henry Dick, WHOI:
A plume is a non-ridge-driven, three-dimensional instability in the mantle (10th February, 2004).
Anonymous:
Plume: A narrow thermal feature, which can be either hot or cold, which rises or sinks because of its anomalous temperature compared to the surrounding fluid. In fluid dynamics a jet has the same meaning. A plume or jet arises from the instability of a thermal boundary layer that is heated from below or cooled from the top.

Anonymous:
Mantle plume: A hot narrow buoyant upwelling rising from deep in the mantle and generally attributed to thermal instability of a thin layer near the core-mantle boundary. In Earth sciences a plume is also defined as a form of convection independent of other kinds of convection or plate tectonics. Plumes are considered to be the way the core gets rid of its heat, while plate tectonics is defined as the way the mantle gets rid of its heat.

Oxford Educational Dictionary:
A column of magma rising from the lower mantle and spreading sideways on reaching the base of the lithosphere, proposed as an explanation of the motion of lithospheric plates and of sites of volcanic activity away from plate margins.
A fluid dynamics definition:
A plume is a hypothetical narrow thermal upwelling (or downwelling) from  a deep (or surface) thermal boundary layer rising (or sinking ) through a homogeneous isothermal  stationary fluid.

Contributed by Don Anderson, January 2004:
Plumes are used in  solid Earth sciences to  rationalize a variety of phenomena including uplift and breakup of continents, oceanic swells, island chains, large igneous provinces, and unusual basalt chemistry or volume.

Interpretations of Morgan's original definition:
I now propose that these hotspots are manifestations of convection in the lower mantle which provides the motive force for continental drift. In my model there are about twenty deep mantle plumes bringing heat and relatively primordial material up to the asthenosphere and horizontal currents in the asthenosphere flow radially away from each of these plumes (Morgan, 1971).

According to this argument, all upward movement of mantle material is confined to about 20 plumes, each plume a few hundred kilometers in diameter, rising from the core–mantle boundary. The plume effectively burns a hole through the overlying crustal plate .. and a volcano results (P. Francis, “Volcanoes” 1976).

From Turner (1969)
A variety of phenomena related under the heading of turbulent buoyant convection from small souces … a plume arises when buoyancy is supplied continuously….

From Tozer (1973)
A narrow buoyant upwelling in fluids of high Peclet number and near unity Prandtl number.

From Hofmann (1997)
A solid-state, narrow upwelling current in the mantle with a diameter of the order of 100 km and originating from a hot, low-density boundary layer located either above the seismic discontinuity at 660 km depth or near the core-mantle boundary at 2,900 km depth..

Contributed by Erik Lundin, 23rd December, 2003:
The Cactoplume: The term “cactoplume” is an adaptation of the term “cactolith” to a plume. A cactolith (Glossary of Geology) is an irregular intrusive igneous body of obscurely cactuslike form, more or less confined to a horizontal zone and appearing to consist of irregularly related and possibly distorted branching and anastamosing dikes that fed a laccolith. The term was introduced by Hunt et al. (1953, p. 151): “a quasi-horizontal chonolith composed of anastamosing ductoliths whose distal ends curl like a harpolith, thin like a sphenolith, or bulge discordantly like an akmolith or ethmolith”. So cactoplumes ought to be able to generate the entire magmatic record. Unfortunately Hunt did not provide a drawing of a cactolith! [Ed: But luckily Erik did - see right]

... the cactoplume ... the ultimate fix for any surface phenomenon

References

  • Hofmann, A.W., Mantle geochemistry: the message from oceanic volcanism, Nature, 385, 219-229, 1997.
  • Turner, J.S., Ann. Rev. Fluid Mech., 1, 29, 1969.
last updated October 2nd, 2007
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