<p>First of all, the idea of a fixed "hotspot" reference frame is (albeit reluctantly) falling out of favour on a geological timescale; see e.g. <a href="http://onlinelibrary.wiley.com/doi/10.1029/GM121p0339/summary">http://onlinelibrary.wiley.com/doi/10.1029/GM121p0339/summary</a> ("As studies of plate motions have advanced, however, it has become clear that the global hotspots do not stay fixed relative to each other...") and <a href="http://adsabs.harvard.edu/abs/2010AGUFM.U51A0010S">http://adsabs.harvard.edu/abs/2010AGUFM.U51A0010S</a> ("Hotspot reference frames can only be confidently tied back to about 130 Ma and there is evidence that mantle plumes have moved relative to each other.") Global Moving Hotspot Reference Frames are in the process of being built, see e.g. <a href="http://adsabs.harvard.edu/abs/2010AGUFMGP24A..03D">http://adsabs.harvard.edu/abs/2010AGUFMGP24A..03D</a></p>

<p>Secondly, identifiable patterns in the distribution of mantle plumes are an area of active research: <a href="https://www.egu.eu/awards-medals/division-outstanding-young-scientists-award/2014/rhodri-davies/">this year's EGU medal for outstanding young scientist was awarded to Rhodri Davies for his work in this area</a>. Key to most arguments are the presence of <a href="https://en.wikipedia.org/wiki/Large_Low_Shear_Velocity_Provinces">Large Low Shear Velocity Provinces</a> (LLSVPs) in the lower mantle, historically assumed to be "slab graveyards" (thermochemical piles created when subducting slabs pool in the lower mantle). The suggestion that these areas were both chemically and thermally distinct from surrounding mantle focussed attention on their margins as a highly probable location for the formation of mantle plumes. However, recent findings (by and cited extensively by Rhodri Davies) increasingly support the idea that these piles are thermal features <em>only</em>, with no chemical difference to surrounding mantle.</p>

<p>Rhodri Davies' research revisits past studies that found hotspots were concentrated along the edges of LLSVPs, and has thoroughly demonstrated that these conclusions are not robust, e.g. to choice of hotspot catalogue, prescribed angular search tolerance (between surface expression and imaged margin), (arbitrary) depth of analysis, and (arbitrary) shear-wave velocity contour. Via Monte Carlo simulations he rules out hotspots being drawn from the margins of the Pacific LLSVP, but cannot rule out the possibility that hotspots are preferentially drawn from the entire areal extent of LLSVPs in both the Pacific and the Atlantic.</p>

<p>RD &amp; his team conclude that present-day hotspot locations are controlled by ancient subduction, rather than the current margins of LLSVPs - which are demonstrated via dynamical simulations to be mobile, even in the presence of dense chemical heterogeneity.</p>

<p>(As a side note, both "hotspots" and "mantle plume" are contested terminology, it's true - but the vast majority of geoscientists believe that mantle plumes <em>do</em> exist. There is complexity to that view, in that the consensus does not require <em>all</em> intraplate volcanism to be the result of atypically hot mantle -- but the idea that mantle plumes simply do not exist, as espoused by <a href="http://mantleplumes.org">mantleplumes.org</a>, does not have wide acceptance.)</p>

CC BY-SA 3.0
2014-11-11T11:38:53.007Z
If the idea that the mantle plumes emerge from the "slab graveyards", then this is a relatively young phenomenon that started only after the initiation of plate tectonics and only after slabs were subduction to sufficient depth. Am I right in my thinking?
Gimelist
CC BY-SA 3.0
2014-04-29T16:53:14.030Z
2014-04-29T16:53:14.030Z
kaberett
<p><strong>Background:</strong></p>

<p>The theory of mantle plumes is useful (although controversial) in explaining the occurrence of intra-plate volcanoes.  The website <a href="http://www.uhh.hawaii.edu/~kenhon/geol205/chain/default.htm">here</a> suggests that "hotspots" exist in fixed locations relative to one another in the core, and thus on a planet like Mars, where there are no tectonic plates, massive volcanoes will form above these "hotspots", but on Earth moving tectonic plates give rise to strings of volcanoes above underlying "hotspots".  The quote below is from the linked website:</p>

<blockquote>
  <p>The image on the right shows some of the other "hot spots" scattered
  about the floor of the Pacific Ocean. It is intriguing, that portions
  of island chains of similar age are parallel to each other. This
  suggest that the "hot spots" themselves remain mostly fixed with
  respect to each other, otherwise the chains might be expect to be
  curvilinear, or trend in different directions as the "hot spots"
  generating them moved independantly.</p>
</blockquote>

<p><strong>Question:</strong></p>

<p>Assuming that mantle plumes remain in fixed locations relative to one another at the core, is there any known pattern for how these mantle plumes are distributed relative to one another (or to fixed landmarks, e.g. axis of rotation), or do they appear to be distributed randomly?</p>

CC BY-SA 3.0
2014-04-28T11:21:21.710Z
http://agp2.igf.edu.pl/agp/files/52/3/Malinowski.pdf - interesting read
Kenshin
<plate-tectonics><volcanoes><mantle><convection><mantle-plumes>
Are mantle plumes distributed around the core randomly or in a known pattern?
Kenshin
# Are mantle plumes distributed around the core randomly or in a known pattern?

(Asked by: username_0 on 2014-04-28)

**Background:**

The theory of mantle plumes is useful (although controversial) in explaining the occurrence of intra-plate volcanoes. The website [here](http://www.uhh.hawaii.edu/~kenhon/geol205/chain/default.htm) suggests that "hotspots" exist in fixed locations relative to one another in the core, and thus on a planet like Mars, where there are no tectonic plates, massive volcanoes will form above these "hotspots", but on Earth moving tectonic plates give rise to strings of volcanoes above underlying "hotspots". The quote below is from the linked website:

> The image on the right shows some of the other "hot spots" scattered
> about the floor of the Pacific Ocean. It is intriguing, that portions
> of island chains of similar age are parallel to each other. This
> suggest that the "hot spots" themselves remain mostly fixed with
> respect to each other, otherwise the chains might be expect to be
> curvilinear, or trend in different directions as the "hot spots"
> generating them moved independantly.

**Question:**

Assuming that mantle plumes remain in fixed locations relative to one another at the core, is there any known pattern for how these mantle plumes are distributed relative to one another (or to fixed landmarks, e.g. axis of rotation), or do they appear to be distributed randomly?

**Tags:** plate-tectonics, volcanoes, mantle, convection, mantle-plumes

> **Comments:**
> **username_0**: http://agp2.igf.edu.pl/agp/files/52/3/Malinowski.pdf - interesting read  

---

## 1 answers

### Answer by username_1 on 2014-04-29. Score: 10 | Accepted answer

First of all, the idea of a fixed "hotspot" reference frame is (albeit reluctantly) falling out of favour on a geological timescale; see e.g. <http://onlinelibrary.wiley.com/doi/10.1029/GM121p0339/summary> ("As studies of plate motions have advanced, however, it has become clear that the global hotspots do not stay fixed relative to each other...") and <http://adsabs.harvard.edu/abs/2010AGUFM.U51A0010S> ("Hotspot reference frames can only be confidently tied back to about 130 Ma and there is evidence that mantle plumes have moved relative to each other.") Global Moving Hotspot Reference Frames are in the process of being built, see e.g. <http://adsabs.harvard.edu/abs/2010AGUFMGP24A..03D>

Secondly, identifiable patterns in the distribution of mantle plumes are an area of active research: [this year's EGU medal for outstanding young scientist was awarded to Rhodri Davies for his work in this area](https://www.egu.eu/awards-medals/division-outstanding-young-scientists-award/2014/rhodri-davies/). Key to most arguments are the presence of [Large Low Shear Velocity Provinces](https://en.wikipedia.org/wiki/Large_Low_Shear_Velocity_Provinces) (LLSVPs) in the lower mantle, historically assumed to be "slab graveyards" (thermochemical piles created when subducting slabs pool in the lower mantle). The suggestion that these areas were both chemically and thermally distinct from surrounding mantle focussed attention on their margins as a highly probable location for the formation of mantle plumes. However, recent findings (by and cited extensively by Rhodri Davies) increasingly support the idea that these piles are thermal features *only*, with no chemical difference to surrounding mantle.

Rhodri Davies' research revisits past studies that found hotspots were concentrated along the edges of LLSVPs, and has thoroughly demonstrated that these conclusions are not robust, e.g. to choice of hotspot catalogue, prescribed angular search tolerance (between surface expression and imaged margin), (arbitrary) depth of analysis, and (arbitrary) shear-wave velocity contour. Via Monte Carlo simulations he rules out hotspots being drawn from the margins of the Pacific LLSVP, but cannot rule out the possibility that hotspots are preferentially drawn from the entire areal extent of LLSVPs in both the Pacific and the Atlantic.

RD & his team conclude that present-day hotspot locations are controlled by ancient subduction, rather than the current margins of LLSVPs - which are demonstrated via dynamical simulations to be mobile, even in the presence of dense chemical heterogeneity.

(As a side note, both "hotspots" and "mantle plume" are contested terminology, it's true - but the vast majority of geoscientists believe that mantle plumes *do* exist. There is complexity to that view, in that the consensus does not require *all* intraplate volcanism to be the result of atypically hot mantle -- but the idea that mantle plumes simply do not exist, as espoused by [mantleplumes.org](http://mantleplumes.org), does not have wide acceptance.)

> **Comments:**
> **username_2**: If the idea that the mantle plumes emerge from the "slab graveyards", then this is a relatively young phenomenon that started only after the initiation of plate tectonics and only after slabs were subduction to sufficient depth. Am I right in my thinking?  

---

