What is a "Typical” Mantle Plume?
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| Datum: | 2010 |
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Інститут геофізики ім. С.I. Субботіна НАН України
2010
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| Schriftenreihe: | Геофизический журнал |
| Online Zugang: | http://dspace.nbuv.gov.ua/handle/123456789/103530 |
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| Zitieren: | What is a "Typical” Mantle Plume? / A. Harris, Ch. Kincaid // Геофизический журнал. — 2010. — Т. 32, № 4. — С. 214. — англ. |
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What is a “Typical” Mantle Plume?
A. Harris, Ch. Kincaid, 2010
University of Rhode Island, Graduate School of Oceanography, Narragansett, USA
Process models for mantle plumes, and indeed
arguments for the existence of mantle plumes, are
largely based on expected characteristics for these
upwelling features. Typically plume models have
large heads (>500 km), moderately slender tails
(~100 km), uniform compositions (lower to upper
mantle/Lherzolite), and high excess temperatures
(200 C or more). Here we present laboratory mod-
els of mantle convection with recycled, chemically
laminated lithosphere which reveal a diversity in size,
composition, temperature and both surface geologi-
cal and geophysical expressions. Results suggest
there is no typical mantle plume, but rather a range
in plume classes. Examples from within the differ-
ent classes can readily explain the diversity in plume
surface expressions, from large igneous provinces
with associated tails (time progressive island
chains), to headless plumes and large (or small)
headed plumes with no tails. The traditional large
headed, uniform composition, high excess tempera-
ture plume was rarely seen in the 25 experiments
conducted to date. Laboratory models utilized a glu-
cose syrup (Ra=105 106) for a working fluid. Mix-
tures of syrup and water were used to introduce
density and viscosity contrasts between the ambi-
ent fluid and a dyed, chilled and layered slab repre-
senting recycled lithosphere. Generally, one layer
of the slab was less dense than the ambient fluid
(representing Harzburgite) and one layer was denser
than the ambient fluid (representing Eclogite). A ther-
mal boundary layer was developed at the base of a
20 20 15 cm tank by uniform basal heating. Inter-
action between the slab layers and fluid within the
thermal boundary layer had a strong influence over
the distribution of thermochemical heterogeneity
within upwelling plumes. A range of repeatable
plume styles emerged from this study. One promi-
nent plume style is characterized by upwellings
growing shortly after slabs enter the thermal bound-
ary layer. These plumes are Harzburgite-rich and
range from cooler (~100 C) than ambient mantle
to nearly equivalent with background temperature.
Two common forms of chemical heterogeneity are
seen, one in which these plumes have a thin
(~10 km), Eclogite core. Plumes of this type that
form from the edge of a slab pile have near perfect
bilateral symmetry, containing half Harzburgite and
half Lherzolite material from within the thermal bound-
ary layer. Another common style of upwelling is re-
corded over a range of parameter combinations and
occurs well after recycled material has reached and
spread within the thermal boundary layer. These are
hotter plumes (~200—400 C excess temperature)
with predictable distributions of both slab compo-
nents (Harzburgite and Eclogite) and ambient ther-
mal boundary layer material (Lherzolite). Length
scales of thermochemical heterogeneity range from
1 km to >100 km depending on chemical density
contrasts and local processes of instability forma-
tion within the basal boundary layer. A number of
cases from distinct upwelling classes are digitized
and used to drive synthetic melting and seismic mod-
els. Results show that more typical “plume-like”
patterns can occur, but more commonly cases show
extreme spatial and temporal discontinuities in melt
production and seismic velocity patterns.
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irk-123456789-1035302016-06-20T03:01:41Z What is a "Typical” Mantle Plume? Harris, A. Kincaid, Ch. 2010 Article What is a "Typical” Mantle Plume? / A. Harris, Ch. Kincaid // Геофизический журнал. — 2010. — Т. 32, № 4. — С. 214. — англ. 0203-3100 http://dspace.nbuv.gov.ua/handle/123456789/103530 en Геофизический журнал Інститут геофізики ім. С.I. Субботіна НАН України |
| institution |
Digital Library of Periodicals of National Academy of Sciences of Ukraine |
| collection |
DSpace DC |
| language |
English |
| format |
Article |
| author |
Harris, A. Kincaid, Ch. |
| spellingShingle |
Harris, A. Kincaid, Ch. What is a "Typical” Mantle Plume? Геофизический журнал |
| author_facet |
Harris, A. Kincaid, Ch. |
| author_sort |
Harris, A. |
| title |
What is a "Typical” Mantle Plume? |
| title_short |
What is a "Typical” Mantle Plume? |
| title_full |
What is a "Typical” Mantle Plume? |
| title_fullStr |
What is a "Typical” Mantle Plume? |
| title_full_unstemmed |
What is a "Typical” Mantle Plume? |
| title_sort |
what is a "typical” mantle plume? |
| publisher |
Інститут геофізики ім. С.I. Субботіна НАН України |
| publishDate |
2010 |
| url |
http://dspace.nbuv.gov.ua/handle/123456789/103530 |
| citation_txt |
What is a "Typical” Mantle Plume? / A. Harris, Ch. Kincaid // Геофизический журнал. — 2010. — Т. 32, № 4. — С. 214. — англ. |
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Геофизический журнал |
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