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| Titel |
Effect of Mantle Rheology on Viscous Heating induced during Ice Sheet Cycles |
| VerfasserIn |
Pingping Huang, Patrick Wu, Wouter van der Wal |
| Konferenz |
EGU General Assembly 2017
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| Medientyp |
Artikel
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| Sprache |
en
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| Digitales Dokument |
PDF |
| Erschienen |
In: GRA - Volume 19 (2017) |
| Datensatznummer |
250138690
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| Publikation (Nr.) |
 EGU/EGU2017-1793.pdf |
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| Zusammenfassung |
| Hanyk et al. (2005) studied the viscous shear heating in the mantle induced by the surface
loading and unloading of a parabolic-shaped Laurentide-size ice sheet. They found that for
linear rheology, viscous heating is mainly concentrated below the ice sheet. The depth extent
of the heating in the mantle is determined by the viscosity distribution. Also, the magnitude
of viscous heating is significantly affected by the rate of ice thickness change. However, only
one ice sheet has been considered in their work and the interactions between ice sheets and
ocean loading have been neglected. Furthermore, only linear rheology has been
considered, although they suggested that non-Newtonian rheology may have a stronger
effect.
Here we follow Hanyk et al. (2005) and computed the viscous dissipation for viscoelastic
models using the finite element methodology of Wu (2004) and van der Wal et al. (2010).
However, the global ICE6G model (Peltier et al. 2015) with realistic oceans is used here to
provide the surface loading. In addition, viscous heating in non-linear rheology, composite
rheology, in addition to linear rheology with uniform or VM5a profile are computed and
compared.
Our results for linear rheology mainly confirm the findings of Hanyk et al. (2005). For
both non-linear and composite rheologies, viscous heating is also mainly distributed near and
under the ice sheets, but, more concentrated; depending on the horizontal dimension of the
ice sheet, it can extend into the lower mantle, but for some of the time, not as deep as that for
linear rheology. For composite rheology, the viscous heating is dominated by the effect of
non-linear relation between the stress and the strain. The ice history controls the time when
the local maximum in viscous heating appears. However, the magnitude of the viscous
heating is affected by mantle rheology as well as the ice loading. Due to viscosity
stratification, the shape of the region with high viscous heating in model VM5a is a little
more irregular than that from uniform viscosity model. However, peak heating in the
VM5a model is as big as 22.5 times that of the chondritic radiogenic heating, and is
much bigger than that from linear rheology with uniform viscosity (3.95 times
the chondritic radiogenic heating), non-linear rheology model (10.14 times) and
composite rheology model (10.04 times). Applications of viscous heating will also be
discussed.
References
Hanyk, L., Matyska, C., & Yuen, D. A. (2005). Short time-scale heating of the Earth’s
mantle by ice-sheet dynamics. Earth, planets and space, 57(9), 895-902.
Wu, P. (2004). Using commercial finite element packages for the study of earth
deformations, sea levels and the state of stress. Geophysical Journal International, 158(2),
401-408.
Van der Wal, W., P. Wu, H. Wang & M.G. Sideris, (2010). Sea levels and uplift rate from
composite rheology in glacial isostatic adjustment modeling, J. Geod., J. Geod.,
50:38-48.
Peltier, W., Argus, D., and Drummond, R. (2015). Space geodesy constrains ice age
terminal deglaciation: The global ICE-6G_C (VM5a) model. Journal of Geophysical
Research: Solid Earth, 120(1): 450-487 |
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