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Shear Band Behavior in Paraffin Wax.

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The final six images in this collection show microsopic shear zones or shear bands in polycrystalline paraffin wax being sheared sinistrally, and rapidly, by hand. The apparatus is the one shown in Fig. 5c. of the review paper. The deformation temperature was room temperature. The photo long edges are about 800µm.

59. This shows the condition of the wax after appreciable, but unknown, prior deformation.


The mainly white area at the top of the field of view marks the position of one of the frosted grips. Below this, running horizontally through about (20,35) and (70,40) are two shear bands which we will call bands 1 and 2. These are marked by alignment of slightly yellow wax crystallites.

Elsewhere there is a steeply right-dipping foliation defined by alignment of other bright crystallites. The black areas are patches where the wax is at extinction, probably because the basal polanes are about parallel to the screen. These patches may be used as crude markers, although some changes occur within them. (Some of the features referred to as "Crystallites" above are probably not really small crystals but kink bands within these larger extinguished crystals.)


The right-dipping foliation between the shear bands has been induced by prior sinistral shearing. The combination of the right-dipping foliation and the shear bands is geometrically similar to the S/C compound foliations in rocks.

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60. See if you can find evidence for sinistral displacement across shear bands 1 and 2 (by comparing this photo with the last).


Shear band 2 has propagated to the left and right (How is propagation measured? With respect to the hanging wall? or footwall? or both? (ans))

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61. Shear band 1 is now accompanied by an en-échelon shear band off its right-hand end. Have shear bands 1 and 2 both accumulated more displacement since the last photo? Or is one active and one locked? (ans)

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