Effects of elasticity on the Rayleigh-Taylor instability: implications for large-scale geodynamics

Details Effects of elasticity on the Rayleigh-Taylor instability: implications for large-scale geodynamics Effects of elasticity on the Rayleigh-Taylor instability: implications for large-scale geodynamics

Feb 2007

adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=2007geoji.168..843k&link_type=abstract

Geophysical Journal International, Volume 168, Issue 2, pp. 843-862.

Astronomy and Astrophysics

Astronomy

11

Elasticity, Gravitational Instability, Lithospheric Dynamics, Mantle Lithosphere, Rayleigh-Taylor Instability

Scientific paper

Although parts of the lithosphere may be expected to behave elastically over certain timescales, this effect is commonly ignored in models of large-scale mantle dynamics. Recently it has been demonstrated that elasticity, and in particular viscoelasticity, may have a significant effect on the buckling instability and on the creation of lithospheric-scale shearzones. It is, however, less clear whether elasticity also has an effect on mantle convection and density-driven lithospheric instabilities. The focus of this work is, therefore, to study the effects of elasticity on the two-layer Rayleigh-Taylor (RT) instability, consisting of a Maxwell viscoelastic layer overlying a viscous layer of lower density. We analyse this problem by performing systematic numerical simulations that are compared with newly derived analytical solutions. It is demonstrated that elasticity can be important for certain parameter combinations; it leads to a speedup of the RT instability. The cause for this speedup is that the RT instability is only sensitive to the viscous fraction of deformation in the viscoelastic layer. Elasticity reduces the viscous fraction of deformation at timescales shorter than the Maxwell relaxation time tM(tM = μ/G, where μ is the viscosity and G the elastic shear module). For plate tectonics on Earth, the parameters are such that the effect of elasticity on instability growth is negligible for most boundary conditions. Whereas elasticity does not (or only slightly) change the timescales for lithospheric detachment of the upper mantle, it does significantly alter the response and stress build-up in the overlying crust. Numerical simulations illustrate this effect for lithospheric detachment and show that peak stresses in a viscoelastic crust are smaller than stresses that develop in a viscous crust. Moreover, if the timescale for delamination of the mantle lithosphere is equal or smaller than the Maxwell relaxation time of the crust, the topography of the crust is increased compared to viscous models.

Affiliated with

Also associated with

No associations

Rating

Effects of elasticity on the Rayleigh-Taylor instability: implications for large-scale geodynamics does not yet have a rating. At this time, there are no reviews or comments for this scientific paper.

If you have personal experience with Effects of elasticity on the Rayleigh-Taylor instability: implications for large-scale geodynamics, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Effects of elasticity on the Rayleigh-Taylor instability: implications for large-scale geodynamics will most certainly appreciate the feedback.

Rate now

Comments { 0 }

Profile ID: LFWR-SCP-O-738820