ESS241H1 Lecture Notes - Lecture 8: Shear Modulus, Grain Boundary, Bulk Modulus
Document Summary
Rheology rs between stress (action ) and strain (response e) strain rate: e"=e/t e. g. 1-% squeezing per 1 hr unit time: e"=0. 1/3600s=2. 8x10^-5s^-1 natural strain rates: 10^-14 ~10^-15 warm more likely to have ductile deform. Deformation analogs spring dashpot block typically combinations of di erent behavious e. g. disco-elastic: delayed recovery. Uids (more) strain rate (lower) grain size (reduce) Deformation at small scales strain can cause deformation at micro scale sometimes accommodated by inter crystalline (or for sediments inter granular) deformation cataclastic ow includes inter granular fracturing, frictional sliding & grain rotation. Crystal-plastic deformation mechanisms below 3km depth mechanical twinning crystal structure ips over accomodate shear stress by shearing crystal changes within layers. Crystal defects di usion of point defects (often vacancies) di usion creep volume di usion-vacancies move through crystal grain boundary di usion dislocation creep slip along line defects i. e. not similar to a fault movement of dislocation front doesn"t weaken mineral.
