Analysis of high-voltage, high-resolution images of lattice defects in experimentally-deformed dolomite

Abstract

Deformation-induced stacking defects in dolomite have been characterised following examination at the cation sublattice level using high-resolution electron microscopy at 500kV. Slip on c (≡{0001}) is observed to produce stacking faults, often de-localised laterally, which are terminated by partial dislocations with Burgers vectors of the form 1/3 [1\(\overline 1 \)00]: a model for the faulted dolomite lattice has been constructed which agrees with the image appearance. Slip on f (≡{10\(\overline 1 \)2}) produces long planar faults which are established as not being stacking faults, in the normal sense, since there appear to be no offsets of the cation sublattice across the faults, nor any general indication of any terminating partial dislocations: it is proposed that the contrast arises from rotational disorder in CO3 groups which has resulted from the prior passage of partial dislocations during deformation.