dynamics of mantle plumes
DESCRIPTION
Dynamics of Mantle Plumes. Methods for modeling basic thermal plumes (with and without tracers) Plumes interacting with plates (and ridges) Plumes in thermo-chemical convection More elaborate proposals for plumes. Dynamics of the mantle…. Fine-scale variations in the Galapagos. - PowerPoint PPT PresentationTRANSCRIPT
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Dynamics of Mantle Plumes
• Methods for modeling basic thermal plumes (with and without tracers)
• Plumes interacting with plates (and ridges)
• Plumes in thermo-chemical convection
• More elaborate proposals for plumes
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Dynamics of the mantle…Dynamics of the mantle…
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(from Harpp and White,2001, G-cubed)
Fine-scale variations
in the Galapagos G
alap
agos
Isl
ands
Global scale: mantle contains both well-mixed regions and heterogeneity
Fine scale heterogeneity
Harpp and White, G-cubed 2001
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Hawaiian emperor track (Steinberger et al. Nature 04)
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From Garnero, Annual Reviews of Earth& Planetary Sciences, 2000
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Figure courtesy of E. Garnero, ASU
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Farnetani et al. 2002: Model 1:
uniform mantle, low viscosity plume
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Farnetani et al. 2002: Model 3: viscosity jump
in transition zone
Thin dense layer at base
Low viscosity in plume
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Farnetani et al: EPSL, 2002Detail of mixing in plume:
black tracers are from basal b.l.grey are from transition zone
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Courtesy of Shijie Zhong,U. Colorado (see:
Entrainment of a dense layer by thermal plumes
Zhong and Hager, Geophysical Journal
InternationalSeptember 2003)
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Courtesy of Shijie Zhong, U. Colorado
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B=1 Ra = 107
Color indicates Temperature
Earth’s surface
Core-mantle boundary
Double Diffusive Convection Model of D”
N. Montague and L. Kellogg, JGR, 2000
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time
time
horizontal distanceN. Montague and L. Kellogg, JGR, 2000
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A dense layer stabilizes the flow
With a dense layer in D”
No dense layer
time
N. Montague and L. Kellogg, JGR, 2000
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B= 1M
ore
tem
pera
ture
-dep
en
den
t vis
cosi
ty
Kellogg and Montague, in preparation
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Hansen & YuenVarying properties with depth allows layering
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Layered convection
experiments by Anne Davaille,
(Nature 402, 756,
Dec. 1999)
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Davaille experiments + several numerical models (redrawn from Davaille, 1999; color points are numerical models from various sources)
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Courtillot, V., Davaille, A., Besse, J., Stock, J.,Earth and Planetary Science Letters, 2003.
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Courtillot, V., Davaille, A., Besse, J., Stock, J.,Earth and Planetary Science Letters, 2003.
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Olympus Mons (Mars)-Hawaii Comparison
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Mixing in 2-D with particles •Added at subduction zones •Removed at mid-ocean ridges
2900 km
670 km
Normalized viscosity
Dep
th
0 km
1 10 100
Hunt and Kellogg, 2000
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Constant viscosity
Pressure-dependent viscosity: smooth increase
Transition zone viscosity: Jump at 670 km
Hunt & Kellogg, 2000 - effect of viscosity on mixing
viscosity
1 10 100
1 10 100
1 10 100
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D. L. Hunt & L. H. Kellogg, 2000 Distribution of heterogeneities
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Heat budget of the Earth (all values given in terawatts)
various sources
Total global heat flow: 44 TW
Continental crust produces: 4.6 to 10 TW
A uniform, depleted mantle could produce: 5 – 7 TW
Total BSE Heat production: 20 TW + (from cosmochemistry)
Requires (AT LEAST) 3 to 10.4 TWproduced elsewhere (mantle or core)
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Lithospheric Conduction
HotspotVolcanism
Plate recycling
Mars?
MercuryMoon
Venus?
IoEarth
Comparisons of mantle cooling regimes
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Kellogg et al., 1999
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After a figure in E. M. Moores, L. H. Kellogg, and Y. Dilek, Ophiolites, Tectonics, and Mantle Convection: a contribution to the "Ophiolite Conundrum", in Optiolites and the Oceanic Crust, GSA Special Paper 349, 3-12, 2000.
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After a figure in E. M. Moores, L. H. Kellogg, and Y. Dilek, Ophiolites, Tectonics, and Mantle Convection: a contribution to the "Ophiolite Conundrum", in Optiolites and the Oceanic Crust, GSA Special Paper 349, 3-12, 2000.
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http://www.nsf.gov/pubs/2004/nsf04593/nsf04593.htm
or link to this from: http://www.csedi.org
National Science Foundation Cooperative Studies Of The Earth's Deep Interior (CSEDI)NSF 04-593
Full Proposal Deadline(s) (due by 5 p.m. proposer's local time):
September 20, 2004 August 25, 2005 and annually thereafter
Synopsis of Program:
The Division of Earth Sciences (EAR) invites the submission of proposals for collaborative, interdisciplinary studies of the Earth's interior within the framework of the community-based initiative known as Cooperative Studies of the Earth's Deep Interior (CSEDI). Funding will support basic research on the character and dynamics of the Earth's mantle and core, their influence on the evolution of the Earth as a whole, and on processes operating within the deep interior that affect or are expressed on the Earth's surface.
Projects may employ any combination of field, laboratory, and computational studies with observational, theoretical, or experimental approaches. Support is available for research and research infrastructure through grants and cooperative agreements awarded in response to investigator-initiated proposals from U.S. universities and other eligible institutions. Multidisciplinary work is required. EAR will consider co-funding of projects with other agencies and supports international work and collaborations.