Lecture 16: Deformation in the crust and the mantle Read KK&V chapter 2.10 HW5 is due today

Crystal  la)ce  

Migra/on  of  disloca/ons  through  crystals  

Disloca/on  density  increase  with  stress  

LiNbO3  

Disloca/ons  in  quartz  

Hirth  and  Tullis,  1992  

Disloca/on  density  vs  differen/al  stress  

Durham  et  al.,  1977  

slope  of  ~0.6  

Disloca/on  velocity:  dependence  on                            stress  and  temperature  

Sta/c  re-­‐crystalliza/on  

Sta/c  re-­‐crystalliza/on:  example  

Freed  and  Burgmann,  2004  

Hector  Mine  eq  

Freed  and  Burgmann,  2004  

Postseismic  relaxa/on:  /me  dependence  

Post-­‐glacial  rebound  from  GRACE  data  

Post-­‐glacial  rebound  from  geode/c  data  

Post-­‐glacial  rebound  from  geologic  data  

Effective rheology

dislocation creep

ij

εv = εD + εG = ADσnD + AGd

−mσ nG

d = d0σ−r

diffusion creep

equilibrium grain size

nD ~ 3nG ~1m ~ 3r ~1

A =C exp −QRT

"

#$

%

&'

Arrhenius temperature dependence

Stocker  and  Ashby,  1973  

Deforma/on  map:  olivine  

ε1

ε1 < ε2