mount erebus(photo nasa) the role of mantle plumes in the earth's heat budget chapman...
TRANSCRIPT
![Page 1: Mount Erebus(photo NASA) The role of mantle plumes in the Earth's heat budget Chapman Conference, August 2005 Guust Nolet With thanks to: Raffaella Montelli](https://reader036.vdocuments.mx/reader036/viewer/2022062800/56649de55503460f94adcbb6/html5/thumbnails/1.jpg)
Mount Erebus(photo NASA)
The role of mantle plumes in theEarth's heat budget
Chapman Conference, August 2005
Guust Nolet
With thanks to:Raffaella Montelli Shun Karato…. and NSF
![Page 2: Mount Erebus(photo NASA) The role of mantle plumes in the Earth's heat budget Chapman Conference, August 2005 Guust Nolet With thanks to: Raffaella Montelli](https://reader036.vdocuments.mx/reader036/viewer/2022062800/56649de55503460f94adcbb6/html5/thumbnails/2.jpg)
space
upper mantle
lower mantle
core
D”
44 TW (observed)
~8 TW
2+3 TW
44-13=31 TW
![Page 3: Mount Erebus(photo NASA) The role of mantle plumes in the Earth's heat budget Chapman Conference, August 2005 Guust Nolet With thanks to: Raffaella Montelli](https://reader036.vdocuments.mx/reader036/viewer/2022062800/56649de55503460f94adcbb6/html5/thumbnails/3.jpg)
8-15 TW16-23 TW coldhot
Fluxing 31 TW through the 670 discontinuity
How much of that is carried byplumes?
![Page 4: Mount Erebus(photo NASA) The role of mantle plumes in the Earth's heat budget Chapman Conference, August 2005 Guust Nolet With thanks to: Raffaella Montelli](https://reader036.vdocuments.mx/reader036/viewer/2022062800/56649de55503460f94adcbb6/html5/thumbnails/4.jpg)
Plume flux from surface observations:
Davie
s, 1
99
8
Buoyancy flux B measured from swell elevation eB = e width vplate = Cp Qc
Observed B indicates low plume flux (~3TW)
w
m
![Page 5: Mount Erebus(photo NASA) The role of mantle plumes in the Earth's heat budget Chapman Conference, August 2005 Guust Nolet With thanks to: Raffaella Montelli](https://reader036.vdocuments.mx/reader036/viewer/2022062800/56649de55503460f94adcbb6/html5/thumbnails/5.jpg)
VP/VP (%) at 1000 km depth PRI-P05
![Page 6: Mount Erebus(photo NASA) The role of mantle plumes in the Earth's heat budget Chapman Conference, August 2005 Guust Nolet With thanks to: Raffaella Montelli](https://reader036.vdocuments.mx/reader036/viewer/2022062800/56649de55503460f94adcbb6/html5/thumbnails/6.jpg)
VP/VP (%) at 1000 km depth PRI-P05
![Page 7: Mount Erebus(photo NASA) The role of mantle plumes in the Earth's heat budget Chapman Conference, August 2005 Guust Nolet With thanks to: Raffaella Montelli](https://reader036.vdocuments.mx/reader036/viewer/2022062800/56649de55503460f94adcbb6/html5/thumbnails/7.jpg)
VS/VS (%) at 1000 km depth PRI-S05
![Page 8: Mount Erebus(photo NASA) The role of mantle plumes in the Earth's heat budget Chapman Conference, August 2005 Guust Nolet With thanks to: Raffaella Montelli](https://reader036.vdocuments.mx/reader036/viewer/2022062800/56649de55503460f94adcbb6/html5/thumbnails/8.jpg)
VS/VS (%) at 1000 km depth PRI-S05
![Page 9: Mount Erebus(photo NASA) The role of mantle plumes in the Earth's heat budget Chapman Conference, August 2005 Guust Nolet With thanks to: Raffaella Montelli](https://reader036.vdocuments.mx/reader036/viewer/2022062800/56649de55503460f94adcbb6/html5/thumbnails/9.jpg)
![Page 10: Mount Erebus(photo NASA) The role of mantle plumes in the Earth's heat budget Chapman Conference, August 2005 Guust Nolet With thanks to: Raffaella Montelli](https://reader036.vdocuments.mx/reader036/viewer/2022062800/56649de55503460f94adcbb6/html5/thumbnails/10.jpg)
Cape Verde toAzores
PRI-P05 PRI-S05
![Page 11: Mount Erebus(photo NASA) The role of mantle plumes in the Earth's heat budget Chapman Conference, August 2005 Guust Nolet With thanks to: Raffaella Montelli](https://reader036.vdocuments.mx/reader036/viewer/2022062800/56649de55503460f94adcbb6/html5/thumbnails/11.jpg)
Easter IslandPRI-P05 PRI-S05
![Page 12: Mount Erebus(photo NASA) The role of mantle plumes in the Earth's heat budget Chapman Conference, August 2005 Guust Nolet With thanks to: Raffaella Montelli](https://reader036.vdocuments.mx/reader036/viewer/2022062800/56649de55503460f94adcbb6/html5/thumbnails/12.jpg)
PRI-P05 PRI-S05
Hawaii
![Page 13: Mount Erebus(photo NASA) The role of mantle plumes in the Earth's heat budget Chapman Conference, August 2005 Guust Nolet With thanks to: Raffaella Montelli](https://reader036.vdocuments.mx/reader036/viewer/2022062800/56649de55503460f94adcbb6/html5/thumbnails/13.jpg)
PRI-P05 PRI-S05
Kerguelen
![Page 14: Mount Erebus(photo NASA) The role of mantle plumes in the Earth's heat budget Chapman Conference, August 2005 Guust Nolet With thanks to: Raffaella Montelli](https://reader036.vdocuments.mx/reader036/viewer/2022062800/56649de55503460f94adcbb6/html5/thumbnails/14.jpg)
PRI-P05 PRI-S05
Tahiti
![Page 15: Mount Erebus(photo NASA) The role of mantle plumes in the Earth's heat budget Chapman Conference, August 2005 Guust Nolet With thanks to: Raffaella Montelli](https://reader036.vdocuments.mx/reader036/viewer/2022062800/56649de55503460f94adcbb6/html5/thumbnails/15.jpg)
Tahiti: comparisons ( T)
(a) PRI-P05(b) Zhao et al., 2004(c) PRI-S05(d) Ritsema et al., 1999
![Page 16: Mount Erebus(photo NASA) The role of mantle plumes in the Earth's heat budget Chapman Conference, August 2005 Guust Nolet With thanks to: Raffaella Montelli](https://reader036.vdocuments.mx/reader036/viewer/2022062800/56649de55503460f94adcbb6/html5/thumbnails/16.jpg)
Rich
ard
Alle
nPRI-P05 PRI-S05
![Page 17: Mount Erebus(photo NASA) The role of mantle plumes in the Earth's heat budget Chapman Conference, August 2005 Guust Nolet With thanks to: Raffaella Montelli](https://reader036.vdocuments.mx/reader036/viewer/2022062800/56649de55503460f94adcbb6/html5/thumbnails/17.jpg)
Upper Mantleonly
CMBorigin
![Page 18: Mount Erebus(photo NASA) The role of mantle plumes in the Earth's heat budget Chapman Conference, August 2005 Guust Nolet With thanks to: Raffaella Montelli](https://reader036.vdocuments.mx/reader036/viewer/2022062800/56649de55503460f94adcbb6/html5/thumbnails/18.jpg)
Bottom line:
Plumes are obese (or we wouldnot see them), with Tmax =100-300K,
Ergo: they contain a lot of calories,
Either: they carry an awful lot of heatto the surface,or: they go terribly slow….
![Page 19: Mount Erebus(photo NASA) The role of mantle plumes in the Earth's heat budget Chapman Conference, August 2005 Guust Nolet With thanks to: Raffaella Montelli](https://reader036.vdocuments.mx/reader036/viewer/2022062800/56649de55503460f94adcbb6/html5/thumbnails/19.jpg)
Can we quantify that qualitative notion?
The plume contains:
H = cPT d3x Joules
But we do not know how fastit rises to the surface!
![Page 20: Mount Erebus(photo NASA) The role of mantle plumes in the Earth's heat budget Chapman Conference, August 2005 Guust Nolet With thanks to: Raffaella Montelli](https://reader036.vdocuments.mx/reader036/viewer/2022062800/56649de55503460f94adcbb6/html5/thumbnails/20.jpg)
Excursion, back to textbook physics:
![Page 21: Mount Erebus(photo NASA) The role of mantle plumes in the Earth's heat budget Chapman Conference, August 2005 Guust Nolet With thanks to: Raffaella Montelli](https://reader036.vdocuments.mx/reader036/viewer/2022062800/56649de55503460f94adcbb6/html5/thumbnails/21.jpg)
Tahiti, 1600 km, T > 150K
actual tomogram T (>150K) output of resolution test
![Page 22: Mount Erebus(photo NASA) The role of mantle plumes in the Earth's heat budget Chapman Conference, August 2005 Guust Nolet With thanks to: Raffaella Montelli](https://reader036.vdocuments.mx/reader036/viewer/2022062800/56649de55503460f94adcbb6/html5/thumbnails/22.jpg)
Tahiti: rise velocity underestimated by factor of 4
Tahiti, 1600 km
Vz from actual tomogram Vz from resolution test image
![Page 23: Mount Erebus(photo NASA) The role of mantle plumes in the Earth's heat budget Chapman Conference, August 2005 Guust Nolet With thanks to: Raffaella Montelli](https://reader036.vdocuments.mx/reader036/viewer/2022062800/56649de55503460f94adcbb6/html5/thumbnails/23.jpg)
For wider plume ( T> 110K) vz underestimated by factor 3
Tahiti, 1600 km
![Page 24: Mount Erebus(photo NASA) The role of mantle plumes in the Earth's heat budget Chapman Conference, August 2005 Guust Nolet With thanks to: Raffaella Montelli](https://reader036.vdocuments.mx/reader036/viewer/2022062800/56649de55503460f94adcbb6/html5/thumbnails/24.jpg)
observed
reductionin tomography and this is the
resolving errorfactor
If the earth vz showsup here in thetomographic image
Then the realearth vz must havebeen close to here
![Page 25: Mount Erebus(photo NASA) The role of mantle plumes in the Earth's heat budget Chapman Conference, August 2005 Guust Nolet With thanks to: Raffaella Montelli](https://reader036.vdocuments.mx/reader036/viewer/2022062800/56649de55503460f94adcbb6/html5/thumbnails/25.jpg)
But what parameters to use at depth?
Forte & Mitrovica , 2001Lithgow-Bertelloni & Richards, 1995
QuickTime™ and aTIFF (LZW) decompressor
are needed to see this picture.
6 1022Pa s
![Page 26: Mount Erebus(photo NASA) The role of mantle plumes in the Earth's heat budget Chapman Conference, August 2005 Guust Nolet With thanks to: Raffaella Montelli](https://reader036.vdocuments.mx/reader036/viewer/2022062800/56649de55503460f94adcbb6/html5/thumbnails/26.jpg)
70110
150
Tahiti estimated heat flux as function of depth
= well resolved values,corrected for bias
![Page 27: Mount Erebus(photo NASA) The role of mantle plumes in the Earth's heat budget Chapman Conference, August 2005 Guust Nolet With thanks to: Raffaella Montelli](https://reader036.vdocuments.mx/reader036/viewer/2022062800/56649de55503460f94adcbb6/html5/thumbnails/27.jpg)
Tahiti1500 km
700 km
![Page 28: Mount Erebus(photo NASA) The role of mantle plumes in the Earth's heat budget Chapman Conference, August 2005 Guust Nolet With thanks to: Raffaella Montelli](https://reader036.vdocuments.mx/reader036/viewer/2022062800/56649de55503460f94adcbb6/html5/thumbnails/28.jpg)
Inferred heat flux Q is too high. Possible solutions
(1) The buoyancy flux at surface underestimates Q at depth
![Page 29: Mount Erebus(photo NASA) The role of mantle plumes in the Earth's heat budget Chapman Conference, August 2005 Guust Nolet With thanks to: Raffaella Montelli](https://reader036.vdocuments.mx/reader036/viewer/2022062800/56649de55503460f94adcbb6/html5/thumbnails/29.jpg)
flux loss factor B
Escape into asthenosphere
mantle not adiabatic
heat diffusion,entrainment
B = B Cp Qc/
delayed or escape at 670?
![Page 30: Mount Erebus(photo NASA) The role of mantle plumes in the Earth's heat budget Chapman Conference, August 2005 Guust Nolet With thanks to: Raffaella Montelli](https://reader036.vdocuments.mx/reader036/viewer/2022062800/56649de55503460f94adcbb6/html5/thumbnails/30.jpg)
Inferred heat flux Q is too high. Possible solutions
(1) The buoyancy flux at surface underestimates Q at depth
(2) The reference viscosity 6 1022 Pas (at 800 km) is too low
![Page 31: Mount Erebus(photo NASA) The role of mantle plumes in the Earth's heat budget Chapman Conference, August 2005 Guust Nolet With thanks to: Raffaella Montelli](https://reader036.vdocuments.mx/reader036/viewer/2022062800/56649de55503460f94adcbb6/html5/thumbnails/31.jpg)
Inferred heat flux Q is too high. Possible solutions
(1) The buoyancy flux at surface underestimates Q at depth
(2) The reference viscosity 6 1022 Pas (at 800 km) is too low
(3) Iron enrichment makes the plume heavier
(4) H2O increases dV/dT, therefore lowers T
![Page 32: Mount Erebus(photo NASA) The role of mantle plumes in the Earth's heat budget Chapman Conference, August 2005 Guust Nolet With thanks to: Raffaella Montelli](https://reader036.vdocuments.mx/reader036/viewer/2022062800/56649de55503460f94adcbb6/html5/thumbnails/32.jpg)
Conclusions
-High viscosity in lower mantle makes convection there 'sluggish' at best
- Large viscosity contrast points to two strongly divided convective regimes in the Earth
- Large flux loss may also imply plume resistance at 670 and/or escape into asthenosphere
![Page 33: Mount Erebus(photo NASA) The role of mantle plumes in the Earth's heat budget Chapman Conference, August 2005 Guust Nolet With thanks to: Raffaella Montelli](https://reader036.vdocuments.mx/reader036/viewer/2022062800/56649de55503460f94adcbb6/html5/thumbnails/33.jpg)
Speculations
- Exchange of material between sluggish lower mantle and less viscous upper mantle is limited (most likely periodic).
- Plumes may carry all of the upward flow of heat (>16TW) through the 670 km discontinuity.
-The next breakthrough (flood basalt?) may be at Cape Verde/Canary Islands, Chatham or Tahiti.
![Page 34: Mount Erebus(photo NASA) The role of mantle plumes in the Earth's heat budget Chapman Conference, August 2005 Guust Nolet With thanks to: Raffaella Montelli](https://reader036.vdocuments.mx/reader036/viewer/2022062800/56649de55503460f94adcbb6/html5/thumbnails/34.jpg)
Equal mass flux hypothesis:
Over time, slabs transport as muchmass into the lower mantle as plumesreturn to the upper mantle.There is no other mass flux throughthe 670 discontinuity